e827 Corn-Soybean-Wheat and Forages Field Guide OSU Extension

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<p>Bulletin 827</p><p>CORN, SOYBEAN,</p><p>WHEAT, AND FORAGES</p><p>FIELD GUIDE</p><p>OHIO STATE UNIVERSITY EXTENSION</p><p>AGRONOMIC CROPS TEAM</p><p>Copyright © 2019, 2014, 2010, The Ohio State</p><p>University</p><p>CFAES provides research and related educational</p><p>programs to clientele on a nondiscriminatory basis.</p><p>For more information, visit cfaesdiversity.osu.edu.</p><p>For an accessible format of this publication, visit</p><p>cfaes.osu.edu/accessibility.</p><p>1</p><p>A</p><p>uthors</p><p>CORN, SOYBEAN, WHEAT AND</p><p>FORAGES FIELD GUIDE</p><p>AUTHORS</p><p>B. A. Ackley OSU Horticulture and Crop Science</p><p>D. B. Beegle PSU Plant Science (Retired)</p><p>A. A. Collins PSU Plant Pathology</p><p>S. W. Culman OSU Environment and Natural Resources</p><p>W. S. Curran PSU Plant Science (Retired)</p><p>A. E. Dorrance OSU Plant Pathology</p><p>S. W. Duiker PSU Plant Science</p><p>P. D. Esker PSU Plant Pathology</p><p>G. A. LaBarge OSU Extension</p><p>E. M. Lentz OSU Extension</p><p>A. J. Lindsey OSU Horticulture and Crop Science</p><p>L. E. Lindsey OSU Horticulture and Crop Science</p><p>D. D. Lingenfelter PSU Plant Science</p><p>M. M. Loux OSU Horticulture and Crop Science</p><p>A. P. Michel OSU Entomology</p><p>H. E. Ozkan OSU Food, Agricultural and Biological Engineering</p><p>P. A. Paul OSU Plant Pathology</p><p>A. L. Raudenbush OSU Entomology</p><p>G. W. Roth PSU Plant Science (Retired)</p><p>R. M. Sulc OSU Horticulture and Crop Science</p><p>N. J. Taylor OSU Plant Pathology (Retired)</p><p>P. R. Thomison OSU Horticulture and Crop Science</p><p>K. J. Tilmon OSU Entomology</p><p>J. F. Tooker PSU Entomology</p><p>H. D. Watters OSU Extension</p><p>J. A. Williamson PSU Plant Science</p><p>Ohio State University Extension</p><p>Ohio Agricultural Research and Development Center</p><p>The Ohio State University</p><p>Penn State Extension</p><p>College of Agricultural Sciences</p><p>Penn State University</p><p>2</p><p>A</p><p>ck</p><p>no</p><p>w</p><p>le</p><p>dg</p><p>m</p><p>en</p><p>ts</p><p>ACKNOWLEDGMENTS</p><p>The Entomological Society of America provided the insect damage keys.</p><p>We would also like to thank OSU Extension Publishing for text editing,</p><p>layout, and development of illustrations.</p><p>PREFACE</p><p>The Corn, Soybean, Wheat, and Forages Field Guide has been designed</p><p>as a guide to be used by scouts, crop advisors, and farmers when they are</p><p>scouting their fields. The guide contains information on insect, disease,</p><p>and weed identification as well as agronomic information that should be</p><p>valuable when checking fields. The guide is divided into seven sections:</p><p>Corn Management, Soybean Management, Wheat Management, Forage</p><p>Management, Weed Identification, Pesticide Application Technology, and</p><p>General Crop Management. Additional publications that might be useful</p><p>in scouting fields are available from Ohio State University Extension</p><p>offices and online at: ohioline.osu.edu, agcrops.osu.edu/publications,</p><p>and extensionpubs.osu.edu. Or visit extension.psu.edu. A listing of OSU</p><p>Extension educators and phone numbers can be found on pages 275-</p><p>278. A listing of Extension specialists and phone numbers is given on</p><p>page 273-274.</p><p>An index of topics included in this Field Guide begins on page 283. This</p><p>index can be used to quickly locate page numbers for your topic of interest.</p><p>http://ohioline.osu.edu</p><p>http://agcrops.osu.edu/publications</p><p>http://extensionpubs.osu.edu</p><p>http://extension.psu.edu</p><p>3</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>3</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>CORN MANAGEMENT</p><p>4</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>4</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>STAGING VEGETATIVE GROWTH</p><p>IN CORN</p><p>LEAF STAGE DEFINITIONS FOR CORN</p><p>There is no standard method for leaf staging corn. The two most widely</p><p>used methods are easy to learn. Both methods begin counting leaves</p><p>with the first true leaf (short and rounded tip).</p><p>The Leaf Collar Method</p><p>This method is the one preferred by most university agronomists. Only</p><p>leaves with visible leaf collars are counted. The leaf collar is the off-color</p><p>green “band” at the base of the leaf blade, near the stem of the corn plant.</p><p>If a plant has three visible leaf collars, then it is described as leaf stage V3.</p><p>Start with first oval-shaped leaf as V1 (see Figure 1). Field defined as being</p><p>at a given stage when at least 50 percent of plants show collars.</p><p>Field corn developmental stages—</p><p>based on the Leaf Collar Method</p><p>Vegetative Stages Reproductive Stages</p><p>VE Emergence R1 Silking</p><p>V1 First Leaf R2 Blister</p><p>V2 Second Leaf R3 Milk</p><p>V3 Third Leaf R4 Dough</p><p>V(n) Nth-node R5 Dent</p><p>VT Tasseling R6</p><p>Physiological</p><p>maturity</p><p>The Horizontal Leaf Method</p><p>This method is most commonly used by crop insurance adjusters and is</p><p>the one referred to in the Defoliation Yield Loss table on page 12 of this</p><p>guide. It differs from the Leaf Collar Method in that leaf collars are ignored.</p><p>The last leaf that is counted is the uppermost leaf that is 40 to 50 percent</p><p>exposed from the whorl, with a leaf tip usually beginning to droop down</p><p>or pointing below the horizontal.</p><p>1. Identify uppermost leaf that is 40 to 50 percent exposed and whose</p><p>tip is below the horizontal.</p><p>2. Typically, a “horizontal leaf” growth stage will be 1 to 2 leaf stages</p><p>greater than the collar method.</p><p>Comparison of the Two Leaf Staging Methods</p><p>A simple relationship exists between the two methods of leaf staging. For</p><p>corn that is younger than about five leaf collars, the Horizontal Leaf Method</p><p>will usually result in leaf stages that are one greater than the Leaf Collar</p><p>5</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>5</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>Method. For example, if the Leaf Collar Method results in a leaf stage of</p><p>V3, the Horizontal Leaf Method would likely result in a 4-leaf stage.</p><p>For corn that is older than five leaf collars, the Horizontal Leaf Method</p><p>will usually result in leaf stages that are two greater than the Leaf Collar</p><p>Method. For example, if the Leaf Collar Method results in a leaf stage of</p><p>V6, the Horizontal Leaf Method would likely result in a 8-leaf stage.</p><p>A Time Line for Corn Growth and Development</p><p>Growth Stage* Approx. GDDs** Cum. GDDs**</p><p>Planting 0 0</p><p>VE Emergence 100 100</p><p>V3 3-leaf collar 246 346</p><p>V6 6-leaf collar 246 592</p><p>V9 9-leaf collar 246 838</p><p>V12 12-leaf collar 182 1020</p><p>V15 15-leaf collar 150 1170</p><p>V18 18-leaf collar 150 1320</p><p>V19 19-leaf collar 50 1370</p><p>VT Tasseling 50 1420</p><p>R1 Silking - 1420</p><p>R2 Blister 266 1686</p><p>R3 Milk 81 1767</p><p>R4 Dough 214 1981</p><p>R5 Dent 343 2324</p><p>R5 Dent - ½ Milk line</p><p>R6 “Black Layer” 327 2650</p><p>*Based on leaf collar method as defined by Abendroth, et al. (2011), “Corn Growth</p><p>and Development,” PMR 1009, Iowa State University Extension, Ames, IA.</p><p>**Approximate growing degree days (GDDs) between growth stages and</p><p>cumulative GDDs since planting according to Nielsen, RL., 2011. Predicting</p><p>Corn Grain Maturity Dates for Delayed Plantings. Corny News Network, Purdue</p><p>Extension. [online] kingcorn.org/news/timeless/RStagePrediction.html.</p><p>GDDs calculated with 86/50 cutoff, base 50 method; see page 260.</p><p>When Lower Leaves Are Missing</p><p>Lower leaves on older plants usually disappear, making leaf stage</p><p>determination difficult (see Figure 1). Staging older corn begins by first</p><p>splitting the stalk neatly down the middle and looking for the first noticeably</p><p>elongated stalk internode. This internode is usually ½ to ¾ inch long (see</p><p>Figure 2). Carefully identify the leaf whose leaf sheath attaches to this</p><p>node. The fifth leaf is usually attached to the node above this elongated</p><p>internode. Continue counting the remainder of the leaves with leaf collars</p><p>to complete leaf stage determination of the plant.</p><p>http://kingcorn.org/news/timeless/RStagePrediction.html</p><p>6</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>6</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>Figure 1.</p><p>Figure 2. Internal anatomy of a 10-leaf stage corn plant</p><p>(Adapted from original drawing by R. Kent Crookston)</p><p>Corn plant at V2 stage of</p><p>development. Arrow points to</p><p>first oval-shaped leaf.</p><p>Corn plant at the V9 stage</p><p>of development. Note: Lower</p><p>2-3 leaves usually fully or</p><p>partially decomposed due to</p><p>stalk expansion and nodal</p><p>root formation.</p><p>7</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>7</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>Predicting Leaf Stage Development in Corn</p><p>Given an understanding of corn leaf stage development and heat</p><p>unit calculation, a grower can predict what leaf stage of development</p><p>a particular field is at given its</p><p>Not a major</p><p>concern in</p><p>the U.S.</p><p>Fusarium</p><p>Whitish-gray colored</p><p>kernels scattered or</p><p>in small groups on the</p><p>ear. Starburst—whitish</p><p>streaks on the caps of</p><p>effected kernels.</p><p>Moderate to</p><p>warm and</p><p>humid during</p><p>silking. Insect</p><p>damage.</p><p>Fumonisins.</p><p>Gibberella</p><p>Pinkish fungal</p><p>growth, usually at the</p><p>tip of the ear.</p><p>Cool, wet</p><p>during the first</p><p>few weeks after</p><p>silking. Insect</p><p>damage.</p><p>Vomitoxin</p><p>is the most</p><p>common.</p><p>Trichoderma</p><p>Dark green fungal</p><p>growth on and</p><p>between kernels</p><p>and over the entire</p><p>ear. Premature</p><p>germination</p><p>(sprouting).</p><p>Warm, wet and</p><p>damage to the</p><p>ear.</p><p>Usually not</p><p>a major</p><p>concern in</p><p>the U.S.</p><p>Diplodia (A), Gibberella (B), Fusarium (C), and</p><p>(D) Trichoderma ear rots of corn</p><p>A B C D</p><p>69</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>69</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>ANTHRACNOSE STALK ROT</p><p>Description: Anthracnose stalk rot is identified by the shiny black</p><p>spots and/or streaks on the outer surface of the stalk. The entire</p><p>stalk of susceptible hybrids may turn black. Depending on the hybrid,</p><p>external discoloration may or may not be accompanied by blackish</p><p>discoloration of the internal stalk tissue. On the other hand, internal</p><p>discoloration may occur without symptoms being evident on the</p><p>outside of the stalk.</p><p>Location: Stalk rot phases of anthracnose can be found throughout</p><p>the state. It is prevalent in continuous, reduced tillage corn fields.</p><p>Time of attack: The disease is favored by rainy weather any time</p><p>from seedling emergence to maturity. Anthracnose stalk rot can be</p><p>detected starting around two weeks prior to physiological maturity.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Till residues</p><p>• Crop rotation</p><p>70</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>70</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>DIPLODIA STALK ROT</p><p>Description: Plants affected by Diplodia stalk rot have small, black</p><p>fungal bodies (pycnidia) beneath the epidermis of the stalks usually</p><p>near the nodes. These fungal bodies are not superficial and cannot</p><p>easily be scraped off.</p><p>Location: Diplodia stalk rot is more common in the southern half of</p><p>Ohio and appears to be associated with continuous corn and reduced</p><p>tillage.</p><p>Time of attack: Wet, warm temperatures in June and July followed by</p><p>drought stress in August and September favor stalk rot.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Crop rotation</p><p>• Till residues</p><p>71</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>71</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>GIBBERELLA STALK ROT</p><p>Description: Gibberella stalk rot is typified by reddish discoloration of</p><p>the pith tissues in weakened or lodged stalks. Under some conditions,</p><p>small, round black “dots” (perithecia of the fungus) may develop at the</p><p>internodes.</p><p>Location: Gibberella stalk rot can occur throughout Ohio.</p><p>Time of attack: Wet, warm temperatures in June and July followed</p><p>by drought stress in August and September favor lodging caused by</p><p>Gibberella stalk rot.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Crop rotation</p><p>• Till residues</p><p>• Reduce damage caused by insects</p><p>72</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>72</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>NUTRIENT DEFICIENCY</p><p>SYMPTOMS IN CORN</p><p>NITROGEN</p><p>• Similar to potassium (especially at later stages of growth), but symptom</p><p>progresses from the leaf tip along the mid-rib toward the base of older,</p><p>lower leaves.</p><p>• Early season nitrogen stress appears as a general chlorosis of the entire</p><p>plant (more apparent on older, lower leaves).</p><p>73</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>73</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>PHOSPHORUS</p><p>• Phosphorus deficiency symptoms appear as a purpling or reddish-</p><p>purpling of older, lower leaves.</p><p>• Stunted overall growth.</p><p>• Deficiency is common, but soil testing can readily reveal soils likely to</p><p>be deficient.</p><p>• Purpling may also be related to the production of anthocyanins which</p><p>is a plant response to stress or a combination of stresses unrelated to</p><p>Phosphorus deficiency. Cool temperatures, high solar intensity, and</p><p>water stress (drought and water-logged conditions) combine to inhibit</p><p>root growth. Other factors including soil compaction, herbicide injury,</p><p>etc., can make the effect even more pronounced.</p><p>74</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>74</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>POTASSIUM</p><p>• Symptoms progress from the leaf tip as a chlorosis along the leaf edge</p><p>toward the base of the leaf on older, lower leaves.</p><p>• Potassium deficiency is quite common in Ohio, but soil testing and</p><p>adequate fertilization will decrease likelihood of deficiency.</p><p>• Drought conditions can contribute to potassium deficiency even when</p><p>soil test potassium levels are adequate.</p><p>• Typically associated with weak stalks.</p><p>75</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>75</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>MAGNESIUM</p><p>• Magnesium deficiency symptoms appear as an interveinal chlorosis</p><p>of older, lower leaves.</p><p>• Severe enough deficiency can cause lower leaves to turn reddish and</p><p>eventually become necrotic.</p><p>• Not common in Ohio, but it has been documented. Primarily isolated</p><p>to eastern Ohio due to soil parent material, but can be found on low</p><p>pH soils across the state.</p><p>• Soil testing will reveal risk of deficiency.</p><p>76</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>76</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>SULFUR</p><p>• Sulfur deficiency symptoms are similar to nitrogen, but unlike nitrogen</p><p>the chlorosis is more visible on newer, upper leaves.</p><p>• Sulfur deficiency has been observed in Ohio primarily on coarse-</p><p>textured soils low in organic matter.</p><p>• Sulfur deficient plants typically have thinner stalks.</p><p>• Discoloration found on youngest leaves first, starting at the base of the</p><p>leaf and progressing toward the tip.</p><p>• May prevent tassel development.</p><p>77</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>77</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>ZINC</p><p>• Zinc deficiency is expressed as a vertical striping of newer, upper leaves</p><p>that occurs between the midrib and leaf margin.</p><p>• Older, lower leaves may appear bleached.</p><p>• Zinc deficiency also causes shorter internodes (and if severe enough</p><p>can cause rosetting).</p><p>• Zinc deficiency has been documented in Ohio, but it is primarily isolated</p><p>to high pH soils or soils that are severely eroded.</p><p>• Saturated soil conditions can induce deficiency.</p><p>78</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>78</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>OTHER NUTRIENT DEFICIENCY</p><p>SYMPTOMS IN CORN</p><p>CALCIUM</p><p>• Failure of new leaves to emerge and unfold.</p><p>• Tips of leaves colorless and covered with a sticky gelatinous substance</p><p>which causes them to adhere to one another.</p><p>• Rare in Ohio.</p><p>COPPER</p><p>• Youngest, upper leaves become yellow and stunted, eventually turning</p><p>pale while the older leaves die back.</p><p>• Dead leaf tissue may appear along the tips and leaf edges in a pattern</p><p>similar to potassium deficiency.</p><p>• Rarely observed in Ohio.</p><p>MANGANESE</p><p>• Interveinal chlorosis of newer, upper leaves.</p><p>• Severe cases exhibit elongated white streaks, the center of which may</p><p>turn brown and fall out.</p><p>• More likely to occur on soils with higher pH and muck soils.</p><p>IRON</p><p>• Newer, upper leaves develop interveinal chlorosis, veins remain green</p><p>in early stages.</p><p>• Progresses rapidly and may eventually turn the entire leaf white.</p><p>• Rarely observed in Ohio.</p><p>BORON</p><p>• Irregularly shaped white spots between veins, which could develop into</p><p>stripes with a waxy, raised appearance.</p><p>MOLYBDENUM</p><p>• Wilted leaves, youngest leaves may twist.</p><p>• Rarely observed in Ohio.</p><p>79</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>79</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>OHIO RECOMMENDED CORN</p><p>NITROGEN FERTILIZER RATES</p><p>Ohio State University corn nitrogen rate recommendations follow</p><p>a unified framework used throughout the Corn Belt. Together with</p><p>six other states (Iowa, Illinois, Indiana, Michigan, Minnesota, and</p><p>Wisconsin), the Ohio recommended nitrogen rates are not based on</p><p>yield goals, but on economic returns. Corn yield responses along with</p><p>corn and nitrogen prices are used to calculate the point at which the</p><p>last unit of added nitrogen returns a yield increase large enough to pay</p><p>for the added nitrogen cost. This approach, called the maximum return</p><p>to nitrogen (MRTN), is favored because of the economic volatility in</p><p>both corn grain and nitrogen fertilizer prices. The past 10 years provide</p><p>ample evidence of</p><p>these fluctuations.</p><p>The MRTN interface requires three inputs: the previous crop grown</p><p>(corn or soybean), price of nitrogen fertilizer, and price received</p><p>per bushel of corn. When corn prices are low, nitrogen rates will</p><p>be reduced; when corn prices rise, recommended nitrogen rates</p><p>will increase. Similarly, the model responds to nitrogen prices,</p><p>recommending high nitrogen rates when nitrogen costs are low, and</p><p>reduces rates when costs are high. The model is housed on an Iowa</p><p>State University website coordinated by Dr. John Sawyer, but each</p><p>state provides their own yield response data and some support for</p><p>website maintenance and updates. When a user selects Ohio as a</p><p>state, they will only find data collected from trials in Ohio. The tool</p><p>can be found here: go.osu.edu/corn-n-rate or at the Iowa State link</p><p>cnrc.agron.iastate.edu.</p><p>Price of Nitrogen Ferilizer ($/lb)</p><p>Price/bushel of corn $0.30 $0.35 $0.40 $0.45 $0.50</p><p>$3.25 185 176 168 162 155</p><p>$3.50 187 180 173 166 160</p><p>$3.75 191 184 176 170 164</p><p>$4.00 195 186 180 174 168</p><p>$4.25 199 190 184 177 171</p><p>$4.50 200 193 185 180 175</p><p>Additional analyses are now being conducted to look at trends with soil</p><p>type and regions in the state to see if it is justified to split the state up</p><p>into separate regions.</p><p>http://go.osu.edu/corn-n-rate</p><p>http://cnrc.agron.iastate.edu</p><p>80</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>80</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>Selecting rates to maximize profitability and not yield can be a difficult</p><p>mindset for the farming community to break. Farmers love reporting</p><p>big yields from their fields. However, farmers need to understand</p><p>that maximizing yields usually translates into reduced profits and</p><p>greater nutrient losses from the field. Now more than ever, the farming</p><p>community needs to continue to proactively address water quality</p><p>issues in the state. Farmers and retailers can use this information to</p><p>look past maximum yield and a reduced bottom line, and instead</p><p>choose profitability and sound nutrient management when selecting</p><p>how much nitrogen to apply to their corn crop this season.</p><p>From the C.O.R.N. NEWSLETTER 2018-07, New Ohio Recommended</p><p>Corn Nitrogen Fertilizer Rates Now Available.</p><p>For Pennsylvania producers, see the corn nitrogen recommendations</p><p>on the website: extension.psu.edu/nitrogen-fertilization-of-corn.</p><p>http://extension.psu.edu/nitrogen-fertilization-of-corn</p><p>81</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>81</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>ESTIMATING NITROGEN LOSSES AFTER</p><p>A SPRING FERTILIZER APPLICATION</p><p>The following tool can be used to assess nitrogen loss and the need for</p><p>sidedress nitrogen when soil samples are not collected. Soil temperature,</p><p>nitrogen form, length of soil saturation, and organic matter all play critical</p><p>roles in determining microbial activity and resultant denitrification of fall</p><p>and/or spring applied nitrogen. As an aid to help make sidedressing</p><p>decisions, University of Minnesota scientists have developed a simple</p><p>question and answer point system. We have adapted that point system</p><p>to Ohio and propose its use for Ohio’s corn crop (see below).</p><p>1. What N source was utilized?</p><p>a. Anhydrous ammonia with nitrification inhibitor 1 pt</p><p>b. Anhydrous ammonia 2 pt</p><p>c. Other fertilizer banded 3 pt</p><p>d. Other fertilizer broadcast 4 pt</p><p>2. When was the N applied?</p><p>a. After April 20 2 pt</p><p>b. Before April 20 5 pt</p><p>3. How much N has been applied?</p><p>a. > 200 lbs/A 1 pt</p><p>b. 150–200 lbs/A 2 pt</p><p>c. 100–150 lbs/A 3 pt</p><p>d. < 150 lbs/A 4 pt</p><p>4. What has been the predominant soil moisture</p><p>status in the field this spring?</p><p>a. Normal 1 pt</p><p>b. Wet 2 pt</p><p>c. Excessively wet (saturated—standing water) 4 pt</p><p>5. What is the crop’s condition?</p><p>a. Green plants > 12 inches tall 1 pt</p><p>b. Green plants < 12 inches tall 2 pt</p><p>c. Chlorotic plants < 12 inches tall 3 pt</p><p>d. Chlorotic plants > 12 inches tall 5 pt</p><p>Total the score and use the guidelines on the next page.</p><p>82</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>82</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>Less than 13 Additional fertilizer not recommended</p><p>13-16 Evaluate again in 4-7 days</p><p>17 or greater Add an additional 40-70 lbs N/A</p><p>The “re-evaluation” option is only viable until you no longer can sidedress.</p><p>While a total score of 17-18 may merit 40 pounds N per acre, a score of</p><p>more than 18 may require higher rates. Research conducted in Illinois</p><p>has found that 50 pounds N per acre was satisfactory for a wide range</p><p>of conditions. Keep in mind that good judgment is still important when</p><p>using various methods to estimate N needs. Also, each field needs to be</p><p>evaluated individually.</p><p>PRE-SIDEDRESS NITRATE TEST</p><p>(PSNT) FOR MANURED FIELDS</p><p>Producers who have applied manure to their fields should consider</p><p>the PSNT as a nitrogen management tool for corn production. This test</p><p>estimates the level of nitrate-nitrogen in a field and is very good for</p><p>determining if there is adequate N for the crop. If not, the test can help</p><p>estimate additional sidedress N that is needed. The optimum time for</p><p>sidedress is between the V4 to V6 growth stage. Samples should be</p><p>collected five to 10 days prior to the time of sidedress when the corn is at</p><p>least 1 foot tall. Avoid sampling for 48 hours after a significant rainfall event.</p><p>The depth of core samples should be 12 inches and taken from 15 to 20</p><p>sites across a uniform area no larger than 20 acres. Samples should be</p><p>dried as quickly as possible. Do not send to laboratories in plastic bags.</p><p>Avoid starter bands and other atypical areas. For injected manure, an</p><p>alternative sampling protocol has been suggested. In this situation, collect</p><p>five cores, 6 inches apart in a line perpendicular to the direction of the</p><p>injection band (It is not necessary to determine the location of the injection</p><p>band). Collect these five cores from at least four locations in the field. Mix</p><p>the cores and collect a composite subsample to send to the lab for analysis.</p><p>Lab selection should be based on accuracy and timeliness of received</p><p>samples and reporting results. Many labs offer next day results for the</p><p>PSNT once the samples are received at the lab. If the results are in excess</p><p>of 30 ppm in Ohio or 21 ppm Nitrate-N in Pennsylvania, adequate nitrogen</p><p>should be available for this year's corn crop. If it is less than 15 ppm in</p><p>Ohio or 10 ppm nitrate-N in Pennsylvania, the normal nitrogen rate should</p><p>be applied. Between 15 and 30 ppm, other factors should be considered</p><p>before reduction of the normal nitrogen rate. In Pennsylvania see Penn</p><p>State Extension Agronomy Facts #17 “Pre-sidedress Soil Nitrate Test for</p><p>Corn” for guidance on making a sidedress N recommendation, available</p><p>at extension.psu.edu/plants/crops/grains/corn/nutrition/pre-sidedress-</p><p>soil-nitrate-test-for-corn.</p><p>http://extension.psu.edu/plants/crops/grains/corn/nutrition/pre-sidedress-soil-nitrate-test-for-corn</p><p>http://extension.psu.edu/plants/crops/grains/corn/nutrition/pre-sidedress-soil-nitrate-test-for-corn</p><p>83</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>83</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>Research from The Ohio State University has shown that in most situations,</p><p>normal nitrogen rates are required at values less than 30 ppm. The</p><p>test only measures nitrate-nitrogen. If samples are collected too soon,</p><p>ammonium nitrogen may have not converted to the nitrate form. Some</p><p>labs include the ammonium value. This value may be used to confirm</p><p>the conversion (or lack of conversion) of ammonium-nitrogen to nitrate-</p><p>nitrogen. However, only use the nitrate value for management decisions.</p><p>Remember that nitrogen is extremely dynamic and very sensitive to the</p><p>weather, thus nitrogen tests such as the PSNT are not close to being 100</p><p>percent accurate. For example, test results may not be useful if heavy</p><p>rains or several days of soil saturation occur between date of sampling</p><p>and reporting of results. In summary, the pre-sidedress nitrogen test has</p><p>been a useful management tool for manured fields, and occasionally</p><p>useful for fields with cover crops.</p><p>THE EARLY SEASON CHLOROPHYLL</p><p>METER NITROGEN TEST FOR CORN</p><p>Another test that can be used to improve sidedress N recommendations,</p><p>especially where manure is part of the system is the chlorophyll meter test.</p><p>A chlorophyll meter instantaneously measures the greenness of a plant</p><p>leaf, which is directly related to the chlorophyll content of the leaf, and thus</p><p>is an indicator of the N status of corn plants and the need for additional N</p><p>for optimum yields. A chlorophyll meter test has many advantages. Taking</p><p>chlorophyll meter readings of corn plants is easy and rapid. The readings</p><p>are taken in the field, so no samples need to be collected, processed,</p><p>and sent to a laboratory for analysis. Results are available immediately</p><p>in the field.</p><p>Important: The chlorophyll meter test should not be used on fields that</p><p>have received more than 15 pounds per acre of fertilizer N at planting</p><p>or any time prior to taking the readings. With more fertilizer N applied</p><p>at planting, the test can give false high readings indicating no need for</p><p>sidedress N when N may actually be needed.</p><p>When using the chlorophyll meter, the procedures must be followed</p><p>exactly to get meaningful results. The chlorophyll meter test is a pre-</p><p>sidedress test. Readings should be taken at about the 6-leaf stage of the</p><p>corn or later. Follow the instructions with the meter for proper operation</p><p>of the meter. For this test, chlorophyll meter readings should always be</p><p>done on leaf five of the plants being tested. The reading is done at a point</p><p>on the leaf approximately 0.5 inch from the edge of the leaf and three-</p><p>quarters of the leaf length from the leaf base. Do not take readings on the</p><p>leaf midrib or too close to the edge. Use your body to shield the meter</p><p>from direct sunlight. Wet leaves may be read if beaded water is shaken</p><p>or rubbed off before inserting the leaf in the meter.</p><p>84</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>84</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>Readings should be taken on 30 representative plants across the field.</p><p>Because other factors can influence the greenness of leaves the most</p><p>accurate method for using this test includes establishing “High N</p><p>Reference” areas in the field. This area could consist of at least two small</p><p>hand-fertilized sections about four rows wide by about 20 feet long, or</p><p>it could be a longer strip that was machine fertilized. Apply more than</p><p>enough N to meet potential crop requirements for this area. Typically,</p><p>at least 150 to 250 pounds of N per acre is applied. The actual rate and</p><p>fertilizer material used is not critical. Mark these areas in the field, and</p><p>when it is time to do the chlorophyll meter readings, take separate readings</p><p>from the reference area and from the rest of the field. If the average</p><p>reading for the field is at least 95 percent of the reference no sidedress N</p><p>is recommended. If the reading in the field is less than 95 percent of the</p><p>reference, a sidedress N application is recommended. In Pennsylvania,</p><p>see Penn State Extension Agronomy Facts #53 “The Early Season</p><p>Chlorophyll Meter Test for Corn” for guidance on making a sidedress N</p><p>recommendation, available at extension.psu.edu/plants/crops/grains/</p><p>corn/nutrition/early-season-chlorophyll-meter-test-for-corn.</p><p>Ohio has tested another corn green color tool, the NDVI sensor. A nitrogen</p><p>rate calculator is available on the Oklahoma State University Sensor Based</p><p>N Rate Calculator website: soiltesting.okstate.edu/sensor-based-n-rate-</p><p>calculator. The work in Ohio indicates that a pre-plant application of an</p><p>N-Rich strip (such as the High N Reference) noted above is very useful.</p><p>Check normalized difference vegetation index (NDVI) at V8 to V12, then</p><p>use calculator #25 Corn-Ohio on the website for an in-season application</p><p>rate.</p><p>USING MODELS TO GUIDE N MANAGEMENT</p><p>Recently a new approach for guiding sidedress N recommendations has</p><p>been developed. Nitrogen models along with site, management, and</p><p>weather information are used to estimate N behavior in the soil-plant</p><p>system in the early growing season up until the time when a sidedress N</p><p>management decision has to be made, and provides information such as</p><p>estimates of N mineralized form soil organic matter and manure, and losses</p><p>of N that can help make a better sidedress N recommendation. Several</p><p>of these models are available commercially. Like the PSNT, chlorophyll</p><p>meter, and NDVI test, these models do not necessarily give the answer,</p><p>but rather provide valuable information that can be used by the farmer to</p><p>make a better decision on sidedress N management.</p><p>LATE SEASON CORNSTALK NITRATE TEST</p><p>A key to improving nitrogen management over time is having reliable</p><p>feedback on how well your nitrogen management is working. Good</p><p>yields and dark green plants are good indicators of adequate nitrogen,</p><p>but they cannot identify over-fertilization of nitrogen, which can be a</p><p>problem, especially with manure. Also, some visual symptoms of nitrogen</p><p>http://extension.psu.edu/plants/crops/grains/corn/nutrition/early-season-chlorophyll-meter-test-for-corn</p><p>http://extension.psu.edu/plants/crops/grains/corn/nutrition/early-season-chlorophyll-meter-test-for-corn</p><p>http://soiltesting.okstate.edu/sensor-based-n-rate-calculator</p><p>http://soiltesting.okstate.edu/sensor-based-n-rate-calculator</p><p>85</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>85</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>deficiency late in the season may not always indicate a yield loss. In fact,</p><p>a general guideline is that as long as there are at least four green leaves</p><p>below the ear on the corn plant at silage harvest time, N was probably</p><p>adequate for maximum yields. The Late Season Cornstalk Nitrate Test</p><p>has been shown in research at a number of locations across the country,</p><p>including Pennsylvania, to be a reliable end-of-season indicator of crop</p><p>nitrogen status.</p><p>Sampling can be done anytime between ¼-milk line, which is just before</p><p>silage harvest, to about three weeks after black layer formation. The figure</p><p>below shows how to determine the kernel milk line.</p><p>DETERMINING KERNEL MILK LINE</p><p>When an ear of corn is broken in half, the tip half (left) shows the smooth</p><p>endosperm, while the butt end (right) shows the embryos. The arrow points</p><p>to the “milk line,” which is the border between the milk and starch layers</p><p>on the tip end of the ear. Source: Penn State Agronomy Guide. Images of</p><p>kernel milk line development shown on page 17.</p><p>To collect a sample, cut 8 inch long sections of corn stalk starting 6 inches</p><p>above the ground from 10 randomly selected representative plants.</p><p>Pruning shears usually work well for taking these samples. Subsequently</p><p>cut these samples into 1 to 2 inch long segments to facilitate drying. If</p><p>possible, dry the samples immediately or send them to the lab as soon</p><p>as possible after collection. If there is more than a day between sampling</p><p>and sending, refrigerate (don’t freeze) the samples until you can send</p><p>them. Keep the samples in paper (not plastic) bags.</p><p>The nitrate N content in the lower stalk of the plant is a good indicator</p><p>of whether the plant had adequate N or was short or excess on N. This</p><p>test is a post-mortem test that tells us how we did, but not what we need</p><p>to do. This test will not tell the farmer which management practices to</p><p>change. However, this test provides vital feedback that is not otherwise</p><p>available about how the nitrogen management on the farm is performing.</p><p>The results of this test will become more valuable as this information is</p><p>86</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>86</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>accumulated over time. By using the test along with management records</p><p>you can see what is working and what is not. The results can be used to</p><p>directly evaluate the impact of management changes by carefully adjusting</p><p>management based on the latest management recommendations and in-</p><p>season nitrogen tests such as the Pre-sidedress Soil Nitrate Test, the Early</p><p>Season Chlorophyll Meter Test or models. Using these tests will result in</p><p>greater nitrogen use efficiency and economic returns to management and</p><p>reduce the potential for negative environmental impact from nitrogen that</p><p>is not efficiently utilized by the crop.</p><p>More information on this test is available in Penn State Extension Agronomy</p><p>Facts #70 “Late Season Cornstalk Nitrate Test,” available at extension.psu.</p><p>edu/plants/crops/grains/corn/nutrition/late-season-cornstalk-nitrate-test/</p><p>extension_publication_file.</p><p>OHIO FERTILIZER</p><p>RECOMMENDATIONS IN</p><p>POUNDS PER ACRE (P2O5 AND</p><p>K2O) FOR CORN FOR GRAIN</p><p>WHEN SOIL TESTS ARE IN THE</p><p>MAINTENANCE RANGE*</p><p>Crop Yield Goal (bu/acre)</p><p>Corn</p><p>crop removal 125 150 175 200 225 250</p><p>P205</p><p>0.35 lb/bu</p><p>43 51 60 68 77 85</p><p>K20</p><p>0.19 lb/bu</p><p>24 29 33 38 43 48</p><p>Notes:</p><p>Updated recommendations are based on work to update the Tri-State Fertilizer</p><p>Recommendations coordinated by Steve Culman, 2014 to 2018, in over 200 on-</p><p>farm trials for P and K.</p><p>*Maintenance range for P (M3) is 20 to 40 ppm. Maintenance range for K (M3)</p><p>is 100 to 150 ppm. If soil test levels above maintenance range, then no nutrient</p><p>application (P and K) is needed. Sample and retest every three to four years.</p><p>If P level is below the critical level, then make an annual application. An</p><p>alternative is to apply 50 percent additional P2O5 every other year. Resample</p><p>and test regularly every three to four years. Band application of P2O5 can be</p><p>beneficial when P test is below maintenance range.</p><p>If CEC is very low or very high an annual K2O application may be warranted.</p><p>Low is below 6 meq/100g and high is above 25 meq/100g. Resample and test</p><p>regularly every three to four years.</p><p>http://extension.psu.edu/plants/crops/grains/corn/nutrition/late-season-cornstalk-nitrate-test/extension_pu</p><p>http://extension.psu.edu/plants/crops/grains/corn/nutrition/late-season-cornstalk-nitrate-test/extension_pu</p><p>http://extension.psu.edu/plants/crops/grains/corn/nutrition/late-season-cornstalk-nitrate-test/extension_pu</p><p>87</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>87</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>OHIO FERTILIZER (P2O5 AND K2O)</p><p>RECOMMENDATIONS FOR CORN</p><p>SILAGE IN POUNDS PER ACRE1</p><p>Nutrient</p><p>Soil Test</p><p>Level</p><p>M-3</p><p>(ppm)</p><p>Realistic Yield Goal (tons/acre)</p><p>20 22 24 26 28 30 32</p><p>P 20-40 66 73 79 86 92 99 106</p><p>K 100-150 160 176 192 208 224 240 256</p><p>Notes:</p><p>1 Adapted from 1995 Tri-State Fertilizer Recommendations for Corn, Soybeans,</p><p>Wheat, and Alfalfa Crop removal rates for corn silage are 3.3 lbs/T for P2O5 and</p><p>8.0 lbs/T for K2O.</p><p>Sample and retest every three to four years.</p><p>Pennsylvania producers, visit the Penn State Extension soil testing website:</p><p>agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks/agronomic.</p><p>http://agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks/agronomic</p><p>88</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>88</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>NUTRIENT SUFFICIENCY RANGES</p><p>FOR CORN</p><p>(Ear leaf sampled at initial silking)</p><p>Nutrient Element Unit Sufficient</p><p>Nitrogen (N) % 2.90–3.50</p><p>Phosphorus (P) % 0.30–0.50</p><p>Potassium (K) % 1.91–2.50</p><p>Calcium (Ca) % 0.21–1.00</p><p>Magnesium (Mg) % 0.16–0.60</p><p>Sulfur (S) % 0.16–0.50</p><p>Manganese (Mn) ppm 20–150</p><p>Iron (Fe) ppm 21–250</p><p>Boron (B) ppm 4–25</p><p>Copper (Cu) ppm 6–20</p><p>Zinc (Zn) ppm 20–70</p><p>Sampling information on page 244.</p><p>89</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>89</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>SOYBEAN MANAGEMENT</p><p>90</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>90</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>DESCRIPTION OF VEGETATIVE AND</p><p>REPRODUCTIVE STAGES</p><p>Stage</p><p>no. Stage Title Abbreviated Description</p><p>VE Emergence Cotyledons above the soil surface.</p><p>VC Cotyledon Unifoliate leaves unrolled sufficiently so the leaf</p><p>edges are not touching.</p><p>V1 First-node One set of unfolded trifoliate leaves unrolled</p><p>sufficiently so the leaf edges are not touching.</p><p>V2</p><p>Second-</p><p>node</p><p>Two sets of unfolded trifoliate leaves unrolled</p><p>sufficiently so the leaf edges are not touching.</p><p>V3 Third-node Three unfolded trifoliate leaves unrolled</p><p>sufficiently so the leaf edges are not touching.</p><p>V(n) nth-node</p><p>V stages continue with the unfolding of trifoiate</p><p>leaves. (n) can be any number beginning with 1</p><p>for the V1 stage.</p><p>R1</p><p>Beginning</p><p>bloom</p><p>One open flower at any node on the main stem.</p><p>R2 Full bloom Open flower at one of the two uppermost nodes</p><p>on the main stem with a fully developed leaf.</p><p>R3</p><p>Beginning</p><p>pod</p><p>Pod 3/16 inch (5 mm) long at one of four</p><p>uppermost nodes on the main stem with a fully</p><p>developed leaf.</p><p>R4 Full pod</p><p>Pod ¾ inch (2 cm) long at one of the four</p><p>uppermost nodes on the main stem with a fully</p><p>developed leaf.</p><p>R5</p><p>Beginning</p><p>seed</p><p>Seed 1/8 inch (3 mm) long in a pod at one of the</p><p>four upper-most nodes on the main stem with a</p><p>fully developed leaf.</p><p>R6 Full seed</p><p>Pod containing a green seed that fills the pod</p><p>cavity at one of the four uppermost nodes on the</p><p>main stem with a fully developed leaf.</p><p>R7</p><p>Beginning</p><p>maturity</p><p>One normal pod on the main stem that has</p><p>reached its mature pod color.</p><p>R8 Full maturity</p><p>Ninety-five percent of the pods that have reached</p><p>their mature pod color. Five to 10 days away from</p><p>15 percent moisture.</p><p>91</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>91</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>ABIOTIC STRESS IN SOYBEANS</p><p>FROST</p><p>Soybeans should be assessed</p><p>for frost damage at least five</p><p>days after suspected frost</p><p>injury to inspect for regrowth.</p><p>If damage occurred above the</p><p>cotyledons, the plant will likely</p><p>recover. If damage occurred at</p><p>or below the cotyledons, the</p><p>plant will not recover. Look for a</p><p>discolored hypocotyl (the “crook”</p><p>of the soybean that first emerges</p><p>from the ground) which indicates that damage occurred below the</p><p>cotyledon.</p><p>FLOOD STRESS</p><p>Symptoms of flood stress</p><p>(saturated soil) include yellow</p><p>stunted plants. Severity of damage</p><p>to soybean depends on soybean</p><p>growth stage and cultivar, duration</p><p>of saturated soils, and weather</p><p>conditions. When plants are</p><p>completely underwater at high</p><p>air temperatures (>80 degrees</p><p>Fahrenheit), they will likely die.</p><p>Cool, cloudy days and cool, clear</p><p>nights increase the survival of a flooded soybean crop. If the waters</p><p>recede quickly and the plants receive some light, they can recover.</p><p>DROUGHT STRESS</p><p>A visual indication of soybean</p><p>water stress includes flipped</p><p>leaves. The flipped leaves expose</p><p>a silver-green underside which</p><p>reflects light. In more severe</p><p>cases, the outer leaves of the</p><p>trifloiate will close together to</p><p>reduce the leaf area exposed to</p><p>sunlight and reduce water loss.</p><p>Water-stressed plants will grow</p><p>slower and have smaller leaves,</p><p>compared to soybeans with adequate moisture.</p><p>92</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>92</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>GREEN STEM SYNDROME</p><p>Green stem syndrome occurs</p><p>when soybeans have mature</p><p>pods, but the stems remain green.</p><p>Green stems on soybean plants</p><p>may be a result of a source/sink</p><p>problem. With hot and dry growing</p><p>conditions, pod set is likely</p><p>reduced. With a limited number of</p><p>pods (sink), there are fewer places</p><p>for the plant’s photosynthesis to</p><p>go (source). Green stem can be</p><p>associated with bean leaf beetle or stink bug injury. It is also associated</p><p>with some fungicide applications.</p><p>POD SHATTER AND HARVEST LOSS</p><p>Empty, curled soybean pods are</p><p>an indication of pod shattering.</p><p>Shatter can occur as a result of</p><p>re-wetting and drying of pods prior</p><p>to harvest. Shattering and other</p><p>harvest losses can account for</p><p>significant yield loss. Four seeds</p><p>per square foot is equivalent to</p><p>one bushel per acre yield loss.</p><p>Photos: Dan Haen, 2014</p><p>93</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>93</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>INSECT SCOUTING CALENDAR</p><p>FOR SOYBEAN</p><p>Pe</p><p>st</p><p>A</p><p>pr</p><p>M</p><p>ay</p><p>Ju</p><p>ne</p><p>Ju</p><p>l</p><p>A</p><p>ug</p><p>Se</p><p>p</p><p>O</p><p>ct</p><p>Se</p><p>ed</p><p>co</p><p>rn</p><p>M</p><p>ag</p><p>go</p><p>t</p><p>Sl</p><p>ug</p><p>s</p><p>B</p><p>ea</p><p>n</p><p>Le</p><p>af</p><p>B</p><p>ee</p><p>tle</p><p>M</p><p>ex</p><p>ic</p><p>an</p><p>B</p><p>ea</p><p>n</p><p>B</p><p>ee</p><p>tle</p><p>G</p><p>re</p><p>en</p><p>C</p><p>lo</p><p>ve</p><p>rw</p><p>or</p><p>m</p><p>G</p><p>ra</p><p>ss</p><p>ho</p><p>pp</p><p>er</p><p>s</p><p>Ja</p><p>pa</p><p>ne</p><p>se</p><p>B</p><p>ee</p><p>tle</p><p>A</p><p>du</p><p>lt</p><p>Tw</p><p>o-</p><p>sp</p><p>ot</p><p>te</p><p>d</p><p>Sp</p><p>id</p><p>er</p><p>M</p><p>ite</p><p>So</p><p>yb</p><p>ea</p><p>n</p><p>A</p><p>ph</p><p>id</p><p>94</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>94</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>SOYBEAN PEST ASSESSMENT</p><p>METHODS</p><p>Defoliation Assessment: To estimate defoliation collect 30 or more</p><p>trifoliates at random and estimate average level of defoliation (see</p><p>examples on next page). Avoid samples from field perimeter.</p><p>Maximum Levels of Defoliation Tolerated By</p><p>Soybeans</p><p>Without Significant Loss in Yield</p><p>From To % Defoliation</p><p>Seedling Bloom 40</p><p>Bloom Pod Fill 15</p><p>Pod Fill Maturation 25</p><p>Pod Injury Assessment: To evaluate pod injury inspect 10 or more</p><p>whole plants, selected at random. Pod injury is highest in the upper</p><p>canopy. When 10 to 15 percent or more of pods exhibit injury seed</p><p>damage is evident, especially if high moisture infection periods trigger</p><p>mold development.</p><p>Sweep Net Sampling of Insect Pests: Trends of increasing or</p><p>decreasing pest activity on soybeans can be determined by periodically</p><p>taking 10 sweeps from five or more locations in a field.</p><p>Assessing Soybean Aphid: Count the number of aphids per</p><p>soybean plant at 30 locations throughout the field, and calculate an</p><p>average number of aphids per plant. For soybean aphid identification,</p><p>see page 103. For soybean aphid speed scouting, see page 104.</p><p>95</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>95</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>SOYBEAN DEFOLIATION LEVELS</p><p>5%</p><p>20%</p><p>40% 50%</p><p>30%</p><p>10%</p><p>96</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>96</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>SOYBEAN PESTS</p><p>SEEDCORN MAGGOT</p><p>Larva and Damage</p><p>Identification and Incidence:</p><p>Soybean emergence failure due</p><p>to feeding by small, yellowish-</p><p>white, legless fly larvae (maggots)</p><p>on germinating seeds. Damage is</p><p>likely to occur in fields that have</p><p>had green material, such as cover</p><p>crops or weeds incorporated into</p><p>the soil and when cool and damp</p><p>soil conditions delay emergence.</p><p>It is possible to plant late and</p><p>avoid the period of highest seedcorn maggot activity; according to the</p><p>University of Wisconsin, peak emergence of seedcorn maggot flies</p><p>occurs after 392 F degree days after January 1st.</p><p>Sampling: Maggots may be detected by inspecting areas in the field</p><p>exhibiting lack of emergence. Check seed to see if maggot damage</p><p>has occurred.</p><p>Economic Threshold: No economic threshold exists for this insect</p><p>and no rescue treatment is available.</p><p>Management Options: Seed maggot injury may be prevented</p><p>by use of seed treatment (not imidacloprid) or soil insecticide. For</p><p>more information, visit aginsects.osu.edu and extension.psu.edu/</p><p>publications/agrs-026.</p><p>5 mm</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>http://extension.psu.edu/publications/agrs-026</p><p>97</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>97</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>SLUGS</p><p>Identification and Incidence: Slugs are not insects, they are</p><p>molluscs and more closely related to snails and clams than to insects.</p><p>In field crops, slugs are particularly prevalent in no-till or reduced-</p><p>till fields with heavy residue and little soil disturbance. They can</p><p>eat virtually all crops and inflict most of their damage during crop</p><p>establishment and early growth in the spring and fall. This damage</p><p>tends to be most severe under cool, wet conditions, which slow crop</p><p>growth and favor slug activity. Slugs typically feed at night and hide in</p><p>residue or soil during the day. They range in color from pale cream to</p><p>gray to shiny black and range in size as adults from less than an inch</p><p>to over 2 inches in length. Small juvenile slugs can damage seeds and</p><p>seedlings reducing stand and may defoliate established stands that</p><p>may delay plant development. Slugs damage soybean by destroying</p><p>the germinating seed prior to emergence and causes significant</p><p>defoliation.</p><p>Sampling: Inspect several areas of the field and determine</p><p>percentage of plants being fed upon and percentage defoliation.</p><p>Another approach to finding slugs is to place artificial shelters across a</p><p>field (1 X 1 foot shingles, old boards, or anything to create a dark, cool,</p><p>moist environment). Several days after putting them out, slugs can be</p><p>found under the shelters during the day. Research suggests that if you</p><p>consistently find one to two slugs per shingle in the early season that</p><p>you may end up with damage. In autumn, scouting for eggs can also</p><p>reveal details on populations to expect in spring.</p><p>Larva and Damage</p><p>98</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>98</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>Research has not been able to identify consistent relationship between</p><p>the amount of slug damage to soybean plants and yield loss.</p><p>Economic Threshold: Treatment may be necessary if defoliation</p><p>is greater than 40 percent on slow growing plants or if plants are</p><p>being killed.</p><p>Management Options: Several bait formulations of metaldehyde</p><p>or chelated iron are labeled for slug control. Research indicates that</p><p>ground beetles and other predators can be significant allies in the fight</p><p>against slugs; populations of these predators will be strongest in fields</p><p>that avoid preventative insecticide applications. For more information,</p><p>visit aginsects.osu.edu and extension.psu.edu/publications/agrs-026.</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>99</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>99</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>BEAN LEAF BEETLE</p><p>Identification and Incidence: Damage to soybeans by bean leaf</p><p>beetle (BLB) extends from feeding of overwintering adults on emerging</p><p>seedlings to pod feeding by second generation adults in the fall.</p><p>Life cycle of BLB includes two generations with the peak of the first</p><p>generation in July and the peak of the second generation in late August</p><p>or September.</p><p>Sampling: Early in the season sample five plants in five locations for</p><p>defoliation. Late in the season, sample for both defoliation and pod</p><p>damage.</p><p>Economic Threshold: Treatment is warranted when BLB adults are</p><p>actively feeding and the defoliation is 40 percent pre-bloom, 15 percent</p><p>bloom to pod-fill and 25 percent pod-fill to harvest. Treatment may be</p><p>needed late in the season for pod damage if 10-15 percent or more of</p><p>the pods are being fed upon and BLB is still present.</p><p>Management Options: Late planted fields will escape defoliation by</p><p>overwintering BLB and limit establishment of first generation. However,</p><p>later planted fields tend to have greater levels of second generation</p><p>BLB and thus more pod injury. Thus, earlier plantings can be used to</p><p>lessen pod damage. Timely application of rescue treatment will reduce</p><p>losses in yield and seed quality. For more information, visit aginsects.</p><p>osu.edu and extension.psu.edu/publications/agrs-026.</p><p>Adult Pod Injury</p><p>http://aginsects.osu.edu</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>100</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>100</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>MEXICAN BEAN BEETLE</p><p>Identification and Incidence: Both the bronze, 16-spotted</p><p>adult Mexican bean beetle (MBB) and the spiny larvae stage cause</p><p>skeletonized foliar injury of soybeans. Egg and pupae stages are also</p><p>found on the foliage. MBB infestations in Ohio occur primarily in the</p><p>eastern and southern regions. Severe defoliation generally occurs in</p><p>late summer when late instar larvae of the second generation reach</p><p>peak activity.</p><p>Sampling: Inspect five plants from five locations and determine the</p><p>percentage of defoliation. Determine the predominant growth stage of</p><p>MBB.</p><p>Economic Threshold: Treatment is warranted when MBB larvae and/</p><p>or adults are actively feeding and the defoliation is 40 percent pre-</p><p>bloom, 15 percent at pod fill and 25 percent at full pod to harvest.</p><p>Management Options: Rescue treatments should be applied in</p><p>a timely manner to prevent peak injury caused by late instar larvae.</p><p>Treatments applied after larvae begin pupating achieve limited results.</p><p>For more information, visit aginsects.osu.edu and extension.psu.edu/</p><p>publications/agrs-026a.</p><p>Adult Larva</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026a</p><p>http://extension.psu.edu/publications/agrs-026a</p><p>101</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>101</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>OTHER INSECT DEFOLIATORS</p><p>JAPANESE BEETLE</p><p>Metallic colored adult Japanese</p><p>beetles (JB) emerge in early July and</p><p>remain abundant until summer. JB</p><p>adults tend to aggregate and are</p><p>often more abundant in pockets in</p><p>the field. Thus, random sampling of</p><p>foliage is important.</p><p>GRASSHOPPER</p><p>During hot summers, various species</p><p>of grasshoppers</p><p>may be abundant,</p><p>especially along grassy borders of</p><p>a field.</p><p>GREEN CLOVERWORM</p><p>This pest is often found in soybeans</p><p>in low numbers and economic</p><p>infestations warranting treatment</p><p>are uncommon.</p><p>SILVER SPOTTED</p><p>SKIPPER</p><p>Larvae feed on soybean foliage</p><p>and web leaflets together but rarely</p><p>considered an economic pest.</p><p>The occurrence of one or more insect</p><p>defoliators in abundance may lead to</p><p>unacceptable defoliation. Defoliation</p><p>levels should be monitored closely,</p><p>especially from bloom to pod-fill. Treatment is warranted when defoliation</p><p>is 40 percent prebloom, 15 percent bloom, and 25 percent pod-fill to</p><p>harvest. For more information, visit aginsects.osu.edu and extension.psu.</p><p>edu/publications/agrs-026.</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>http://extension.psu.edu/publications/agrs-026</p><p>102</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>102</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>TWO-SPOTTED SPIDER MITE</p><p>Identification and Incidence:</p><p>Drought conditions initiated</p><p>during the spring may lead to</p><p>the development of two-spotted</p><p>spider mite (TSSM) outbreaks by</p><p>early or mid-summer. Initial signs of</p><p>infestations will be evident where</p><p>drought stress is most severe.</p><p>Foliage discoloration and mites</p><p>will be detected on the underside</p><p>of the foliage. Use of a hand lens</p><p>is advised to detect presence of</p><p>adults and immature stages. Mite</p><p>eggs appear as clear or yellow</p><p>marbles under magnification.</p><p>Recently hatched nymphs have</p><p>six legs compared to later nymphs</p><p>and adults, which have eight legs.</p><p>Sampling: Inspect plants</p><p>especially along the field margins</p><p>but also farther inside the field for</p><p>mites and damage. Record the</p><p>stages of mites that are present in</p><p>the field.</p><p>Economic Threshold: Economic</p><p>thresholds have not been</p><p>established for two-spotted spider</p><p>mites. Treatment is warranted if</p><p>infested areas begin to increase</p><p>in size and weather forecasts</p><p>continue to call for hot, dry weather.</p><p>Management Options: Treatment of TSSM may be applied by air or</p><p>ground equipment. Aerial treatments require the use of a miticide with</p><p>systemic activity. Onset of cool and wet weather conditions may reduce</p><p>TSSM infestations. For more information, visit aginsects.osu.edu and</p><p>extension.psu.edu/publications/agrs-026.</p><p>Injury</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>103</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>103</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>SOYBEAN APHID</p><p>Identification and Incidence: The soybean aphid is a small,</p><p>yellow to green aphid with distinct black tailpipes, or cornicles, on the</p><p>abdomen. Adults lay live young rather than eggs. Early in the season</p><p>the aphids will be found on the upper leaves. As populations increase,</p><p>they can be found on the upper stems and later on the lower leaves.</p><p>Sampling: Sample 20 plants from different locations throughout the</p><p>field and count the number of aphids per plant.</p><p>Economic Threshold: The economic threshold for soybean aphid</p><p>is 250 soybean aphids per plant, with an increasing population</p><p>density. Thus, at least two samples are needed to determine whether</p><p>the population size is rising. After the R5 growth stage there is no</p><p>economic return to treating.</p><p>Management Options: There are several predators, including</p><p>lady beetles, which may help take care of this aphid. If populations</p><p>reach 250 aphids per plant and the density is rising, then the use of</p><p>an insecticide might be needed. Resistant soybean varieties are now</p><p>available that offer partial control of soybean aphid, although those</p><p>fields should still be scouted. For more information, visit aginsects.osu.</p><p>edu and extension.psu.edu/publications/agrs-026.</p><p>Photo: Roy Scott</p><p>http://aginsects.osu.edu</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>104</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>104</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>SOYBEAN APHID SPEED SCOUTING</p><p>Speed Scouting is a tactic to help make treatment decisions and can</p><p>replace having to count all aphids on a plant, greatly reducing sampling</p><p>time. Speed Scouting uses an “infested” and “non-infested” determination</p><p>for each plant, rather than the average number of aphids per plant, to</p><p>determine if treatment is needed. If a plant has less than 40 aphids, it is</p><p>considered non-infested; if more than 40 or more aphids, it is considered</p><p>infested. It uses the same economic threshold, which is still 250 aphids</p><p>per plant.</p><p>1. Select the first plant at random. If less than 40 aphids are on the</p><p>entire plant, record a minus [–] for a non-infested plant. If more than</p><p>40 aphids are on the plant, STOP counting, and record a plus [+] for</p><p>that infested plant.</p><p>2. Select another plant at random 30 steps away from the first plant, and</p><p>repeat step 1.</p><p>3. Repeat steps 1 and 2 until 11 plants are sampled in different areas of</p><p>the field.</p><p>4. Make a decision using the total number of “infested” plants. If less</p><p>than six plants are infested, stop sampling and come back in a week.</p><p>If seven to 10 plants are infested, continue sampling five additional</p><p>plants. If all 11 plants are infested, i.e., have at least 40 or more aphids,</p><p>an insecticide application should be made.</p><p>5. If the decision is to continue sampling, count aphids on an additional</p><p>five plants for a total of 16 plants. If the new number of infested plants</p><p>is less than 10, stop sampling; 11 to 14 plants, continue sampling; greater</p><p>than 15, then treat. If continuing to sample is the decision, sample five</p><p>more plants (21 total); new numbers are less than 14 infested plants =</p><p>stop; 15 to 18 = continue; and greater than 19 = treat. However, after 21</p><p>plants are sampled, if you have reached 15 to 18 infested plants, you</p><p>should take another sample in three to four days and begin from step 1.</p><p>6. Another suggestion is that a treatment decision should be confirmed a</p><p>second time three to four days later. If after a second sample is taken</p><p>with the decision to treat, apply an insecticide within three to four days.</p><p>7. As long as a “do not treat” decision is made, continue to sample the</p><p>field every seven to 10 days until plants reach mid-R5 growth stage. At</p><p>that time it is doubtful if soybean aphids can cause economic losses.</p><p>105</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>105</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>STINK BUGS</p><p>Identification and Incidence: There are many species of stink</p><p>bugs that feed on soybean including brown marmorated stink bug</p><p>(BMSB), green, red shouldered, and brown stink bugs. Stink bugs</p><p>injure soybean in the latter half of the season by feeding on pods and</p><p>seeds, resulting in lower yields and reductions in seed quality, the latter</p><p>being a major concern when soybean is grown for seed or food grade</p><p>purposes.</p><p>Sampling: Populations tend to accumulate first on field edges. Stink</p><p>bugs are sampled using a sweep net, taking 10 sweeps in at least five</p><p>locations. Nymph and adult stink bugs of all species should be counted</p><p>together and recorded. For BMSB, insects might need to be counted</p><p>directly on the plant for the number of stink bugs per foot.</p><p>Economic Threshold: Treatment is warranted when stink bugs reach</p><p>four bugs per 10 sweeps or two BMSB per foot for regular soybeans. If</p><p>grown for seed or food grade, the threshold is dropped to two bugs per</p><p>10 sweeps or a single stink bug per foot.</p><p>Management Options: Timely application of rescue treatment will</p><p>reduce losses in yield and seed quality. If economically significant</p><p>populations are mainly on field edges, a border treatment can</p><p>work well for controlling the majority of stink bugs in the field. For</p><p>more information, visit aginsects.osu.edu and extension.psu.edu/</p><p>publications/agrs-026.</p><p>Pod Injury</p><p>BMSB Adult</p><p>GSM Adult</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>http://extension.psu.edu/publications/agrs-026</p><p>106</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>106</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>YIELD REDUCTION FROM WEEDS IN</p><p>SOYBEANS</p><p>Weed Species</p><p>% Soybean Yield Loss</p><p>1 2 4 6 8 10</p><p>Number weeds or clumps/100 ft2</p><p>Giant ragweed 0.1 0.2 0.4</p><p>0.5 0.8 1.0</p><p>Cocklebur 0.4 0.8 1.6 2.4 3.2 4.0</p><p>J. artichoke 0.4 0.8 1.6 2.4 3.2 4.0</p><p>Pigweeds 0.8 1.6 2.4 4.0 6.0 8.0</p><p>Lambsquarters 0.8 1.6 2.4 4.0 6.0 8.0</p><p>Velvetleaf 3.2 6.4 9.6 12.8 16.0 20.0</p><p>Morningglory 3.2 6.4 9.6 12.8 16.0 20.0</p><p>Jimsonweed 3.2 6.4 9.6 12.8 16.0 20.0</p><p>Pennsylvania</p><p>smartweed</p><p>3.2 6.4 9.6 12.8 16.0 20.0</p><p>Giant foxtail* 2.0 4.0 6.8 10 12.8 17.6</p><p>Shattercane** 0.8 2.0 3.2 4.4 5.6 7.2</p><p>Volunteer corn 0.4 0.8 1.2 1.6 2 2.4</p><p>*5 to 8 foxtail stems per clump.</p><p>**2 to 3 shattercane stems per clump.</p><p>107</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>107</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>HERBICIDE INJURY DIAGNOSIS</p><p>SOYBEANS</p><p>GERMINATION/EMERGENCE</p><p>Poor germination and uneven emergence</p><p>• Misapplication of 2,4-D or dicamba for burn-down in the spring prior</p><p>to soybean planting. Allow seven to 30 days, depending upon rate,</p><p>between 2,4-D ester application and soybean planting.</p><p>• Severe injury from sulfentrazone or flumioxazin caused by low organic</p><p>matter soils, high rainfall and cool temperatures.</p><p>COTYLEDON/YOUNG PLANT</p><p>Cotyledon burn, veinal chlorosis, and/or stunted plants</p><p>• Sulfentrazone or flumioxazin injury due to low organic matter soils,</p><p>high rainfall and cool temperatures, or splash up of treated soil onto</p><p>young plants.</p><p>Leaf puckering/shortened midrib/“drawstring” leaves</p><p>• Excessive rates and/or cold, wet conditions following application</p><p>of acetamide herbicides: metolachlor, s-metolachlor, alachlor,</p><p>dimethenamid (shoot inhibitors).</p><p>Leaf burn on margins of older leaves</p><p>• Excessive rates or wet conditions following application of metribuzin,</p><p>or carryover of triazine (atrazine, simazine) herbicides.</p><p>Leaf burn on young and old leaves</p><p>• Postemergence applications of PPO-inhibiting herbicides: Aim, Cadet,</p><p>Cobra/Phoenix, Flexstar, Reflex, Resource or Ultra Blazer. Use of crop oil</p><p>concentrates and UAN during hot, humid conditions may increase injury.</p><p>Leaf puckering/cupping/epinasty</p><p>• Growth regulators (2,4-D, 2,4-DB, Crossbow, dicamba, Status, MCPA,</p><p>Stinger, Tordon). Spray drift from nearby applications should follow wind</p><p>channels. Hot, moist conditions up to three days following application</p><p>of a growth regulator may lead to volatilization. Injury from volatilization</p><p>does not necessarily reduce yields.</p><p>In some instances similar symptoms are present where a growth regulator</p><p>can be ruled out. Current theories explain this phenomenon as a plant</p><p>hormone response regulated in the apical meristem of the plant, which</p><p>may be initiated as a result of plant stress coupled with or without</p><p>postemergence herbicide application. Effect on yield is probably minimal.</p><p>108</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>108</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>Bleaching (white) of leaves</p><p>• Potential carryover of mestotrione (Callisto, Lexar/Lumax), most likely</p><p>from late-season postemergence application the prior year.</p><p>Swollen or cracked hypocotyls/pruned roots/brittle</p><p>stems</p><p>• Excessive rates of DNA herbicides (pendimethalin, trifluralin), or high</p><p>rainfall following preemergence application. Lateral roots may be short</p><p>and thick.</p><p>Interveinal chlorosis/stunting/purple mid-veins/</p><p>deformed leaves</p><p>• Usually associated with amino acid inhibitors. Could result from drift or</p><p>tank contamination with products containing nicosulfuron, rimsulfuron,</p><p>primisulfuron, glyphosate, halosulfuron. Can also be due to plant stress</p><p>in conjunction with the application of Classic, Extreme/ThunderMaster,</p><p>FirstRate, Harmony GT, Pursuit, Raptor, Scepter or Synchrony STS.</p><p>New growth will be the first to yellow. Severe injury will result in death</p><p>(browning) of growing point and stem pith tissue and eventual necrosis</p><p>of leaf tissue.</p><p>BLOOM/POD SET</p><p>Speckled leaves</p><p>• Spray drift from nearby application of a cell membrane disruptor</p><p>(paraquat).</p><p>Leaf puckering</p><p>• Growth regulator type herbicides (2,4-D, dicamba, Stinger). Should</p><p>not appear this late in the season, but the possibility does exist. Refer</p><p>to the discussion on leaf puckering/cupping/epinasty in “Cotyledon/</p><p>Young plant” section.</p><p>109</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>109</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>TIME OF DISEASE SYMPTOM</p><p>OCCURRENCE ON SOYBEANS</p><p>D</p><p>is</p><p>ea</p><p>se</p><p>A</p><p>pr</p><p>M</p><p>ay</p><p>Ju</p><p>ne</p><p>Ju</p><p>l</p><p>A</p><p>ug</p><p>Se</p><p>p</p><p>O</p><p>ct</p><p>Py</p><p>th</p><p>iu</p><p>m</p><p>S</p><p>ee</p><p>d</p><p>Ro</p><p>t a</p><p>nd</p><p>D</p><p>am</p><p>pi</p><p>ng</p><p>O</p><p>ff</p><p>Ph</p><p>yt</p><p>op</p><p>ht</p><p>ho</p><p>ra</p><p>D</p><p>am</p><p>pi</p><p>ng</p><p>O</p><p>ff</p><p>an</p><p>d</p><p>Ro</p><p>ot</p><p>R</p><p>ot</p><p>R</p><p>hi</p><p>zo</p><p>ct</p><p>on</p><p>ia</p><p>S</p><p>ee</p><p>d</p><p>Ro</p><p>t a</p><p>nd</p><p>S</p><p>te</p><p>m</p><p>R</p><p>ot</p><p>B</p><p>ac</p><p>te</p><p>ria</p><p>l L</p><p>ea</p><p>f B</p><p>lig</p><p>ht</p><p>B</p><p>ro</p><p>w</p><p>n</p><p>Sp</p><p>ot</p><p>D</p><p>ow</p><p>ny</p><p>M</p><p>ild</p><p>ew</p><p>B</p><p>ea</p><p>n</p><p>Po</p><p>d</p><p>M</p><p>ot</p><p>tle</p><p>V</p><p>iru</p><p>s</p><p>Sc</p><p>le</p><p>ro</p><p>tin</p><p>ia</p><p>S</p><p>te</p><p>m</p><p>R</p><p>ot</p><p>o</p><p>r W</p><p>hi</p><p>te</p><p>M</p><p>ol</p><p>d</p><p>Su</p><p>dd</p><p>en</p><p>D</p><p>ea</p><p>th</p><p>S</p><p>yn</p><p>dr</p><p>om</p><p>e</p><p>St</p><p>em</p><p>C</p><p>an</p><p>ke</p><p>r</p><p>So</p><p>yb</p><p>ea</p><p>n</p><p>C</p><p>ys</p><p>t N</p><p>em</p><p>at</p><p>od</p><p>e</p><p>B</p><p>ro</p><p>w</p><p>n</p><p>St</p><p>em</p><p>R</p><p>ot</p><p>C</p><p>ha</p><p>rc</p><p>oa</p><p>l R</p><p>ot</p><p>Po</p><p>d</p><p>an</p><p>d</p><p>St</p><p>em</p><p>B</p><p>lig</p><p>ht</p><p>Ph</p><p>om</p><p>op</p><p>si</p><p>s</p><p>Se</p><p>ed</p><p>R</p><p>ot</p><p>So</p><p>yb</p><p>ea</p><p>n</p><p>R</p><p>us</p><p>t</p><p>110</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>110</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>SOYBEAN DISEASES</p><p>PHYTOPHTHORA DAMPING-OFF AND</p><p>ROOT ROT</p><p>Description: Phytophthora damping-off is recognized as a pre- or</p><p>post-emergence damping off. Affected seedlings have brown, water-</p><p>soaked lesions on the roots, hypocotyl, and cotyledons.</p><p>Location: Phytophthora root rot is primarily a problem in the heavy</p><p>clay, poorly drained soils throughout Ohio. This disease has re-</p><p>emerged as a major pathogen of soybeans due to the adaptations by</p><p>the Phytophthora populations to all of the commonly deployed Rps</p><p>genes (Rps1a, Rps1c, Rps1k, and Rps3a) as well as fewer varieties with</p><p>high levels of partial resistance.</p><p>Time of infection: Plants of any age can be infected, and infections</p><p>occur when soils are saturated. The best time to see symptom</p><p>development is one to two weeks after a heavy rain.</p><p>Management:</p><p>• Resistant varieties</p><p>• Crop rotation</p><p>• Improve drainage</p><p>• Fungicide seed treatments that target watermolds</p><p>111</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>111</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>SOYBEAN RUST</p><p>Description: Lesions are very, very small and appear necrotic on</p><p>the top side of the leaf. On the underside of the leaf, pustules form,</p><p>which are raised. Under high humidity these craters open and the</p><p>spores (urediniospores) can be seen. Soybean rust causes premature</p><p>defoliation, fewer seeds per pod, decreased number of filled pods per</p><p>plant and early maturity which all contribute to yield loss.</p><p>Time of infection: Rust, to date, has been limited to the southern</p><p>states, where it has overwintered in the Gulf states and then has built</p><p>up late in the growing season. Soybeans appear to be most susceptible</p><p>following flowering.</p><p>Monitoring and management: Soybean rust is monitored</p><p>throughout the south in order to identify key areas where high levels</p><p>of potential inoculum exist. Management is based on risk. Low risk</p><p>indicates that very low levels of inoculum are present in the southern</p><p>United States and there is little chance the soybean rust will arrive in</p><p>Ohio or impact the crop. Moderate risk indicates that high levels of</p><p>inoculum are present in nearby states at levels that with the right rain</p><p>storm may bring significant levels to Ohio. High risk indicates that rust</p><p>has been found in Ohio and there is still time in the growing season for</p><p>it to negatively impact the crop.</p><p>Note: To date, no soybean rust lesions have been identified in Ohio.</p><p>Leaf Close-up of pustule</p><p>112</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>112</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>RHIZOCTONIA ROOT AND STEM ROT</p><p>Description: Rhizoctonia infects seed, hypocotyls, and roots of</p><p>soybeans. Brick red lesions form on plants. Plants that are not killed will</p><p>appear yellow and stunted late in the season.</p><p>Location: Rhizoctonia is a soil-borne pathogen that is present in most</p><p>fields throughout Ohio.</p><p>Time of infection: Rhizoctonia can infect plants across a wide variety</p><p>of temperature and moisture conditions. It is found most often in</p><p>seasons that begin very wet and then turn dry.</p><p>Management:</p><p>• Crop rotation</p><p>• Fungicide seed treatments that target true fungi</p><p>113</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>113</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>PYTHIUM SEEDLING DAMPING-OFF</p><p>AND</p><p>ROOT ROT</p><p>Description: Pythium, like phytophthora, is another type of water mold</p><p>that can infect seeds, seedlings, and roots when soils are saturated.</p><p>Lesions can range in color from light tan to dark brown and can cover</p><p>the whole root and hypocotyl. They can be found in wet spots as well</p><p>as compacted areas of fields.</p><p>Location: Throughout Ohio, but most severe in fields with low organic</p><p>matter and poor drainage.</p><p>Time of infection: Anytime during the growing season when fields</p><p>are saturated, but the most severe damage is shortly after planting prior</p><p>to seedling emergence.</p><p>Management:</p><p>• Improve drainage</p><p>• Fungicide seed treatments that target watermolds</p><p>• Crop rotation</p><p>114</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>114</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>FUSARIUM ROOT ROT</p><p>Description: Fusarium produces</p><p>dark brown to tan discolorations</p><p>on the roots and seeds. In cases</p><p>where high levels of soil moisture</p><p>are present, white to pinkish-red</p><p>mycelial growth can be found on</p><p>the roots and seeds.</p><p>Location: Fusarium is a common</p><p>residue-borne plant pathogen.</p><p>Infections will be higher in fields</p><p>that are no-till or have a lot corn</p><p>and wheat residue remaining in</p><p>the field.</p><p>Time of infection: Our studies to</p><p>date have only confirmed this as</p><p>a seed and seedling pathogen in</p><p>which infections occur shortly after</p><p>planting.</p><p>Management:</p><p>• Fungicide seed treatment that</p><p>target true fungi</p><p>• Reduce corn and wheat residue through tillage or rotation</p><p>115</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>115</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>BACTERIAL LEAF BLIGHT</p><p>Description: Bacterial leaf blight appears as small angular, water-</p><p>soaked dark spots surrounded by a narrow yellow halo. The centers</p><p>of lesions may fall out or tear leaving the leaves with a ragged</p><p>appearance.</p><p>Location: Bacterial leaf blight is rare, but can occur throughout Ohio.</p><p>Time of infection: Bacterial leaf blight can be found throughout the</p><p>growing season and is spread by driving rain from infected cotyledons</p><p>to newly developing leaves.</p><p>Management:</p><p>• Resistant varieties</p><p>• Crop rotation</p><p>116</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>116</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>BACTERIAL PUSTULE</p><p>Description: Another bacterial leaf disease where dark spots are</p><p>surrounded by bright yellow. On the underside of leaves, the tissue</p><p>forms pustules which appear very similar to soybean rust. The necrotic</p><p>areas are much larger than soybean rust.</p><p>Location: Tends to be rare but has been found throughout Ohio.</p><p>Time of infection: Any time during the year but more prominent</p><p>during wet seasons. Bacteria are easily spread by wind driven</p><p>splashing rain.</p><p>Management:</p><p>• Resistant varieties</p><p>• Crop rotation</p><p>Note: Since this disease is caused by a bacterium, fungicide</p><p>applications will be ineffective.</p><p>117</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>117</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>BROWN SPOT</p><p>Description: Brown spot is a fungal disease that produces irregular,</p><p>dark brown spots that vary in size from flecks to 3/16 inch in diameter.</p><p>Spots coalesce, turn a darker brown and infected areas turn chlorotic</p><p>or yellow. Affected leaves are primarily limited to the lower canopy but</p><p>may reach the mid-canopy in highly susceptible varieties.</p><p>Location: Brown spot occurs throughout Ohio, but is especially</p><p>prevalent in fields where soybeans follow soybeans.</p><p>Time of infection: Spread of brown spot occurs early in the season</p><p>as spores (conidia) are splashed from residue onto unifoliate leaves.</p><p>Wet conditions and heavy rain splash spreads the fungus upwards in</p><p>the plant canopy.</p><p>Management:</p><p>• Resistant varieties</p><p>• Crop rotation</p><p>• Tillage to bury soybean residue</p><p>118</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>118</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>DOWNY MILDEW</p><p>Description: Downy mildew appears on the upper surface of young</p><p>leaves as pale green to yellow spots that enlarge into bright yellow</p><p>lesions of indefinite size and shape. During moist weather lesions on</p><p>the lower leaf surface are covered with the tufts of white mold. Seeds</p><p>may be encrusted with dull, dried whitish mold.</p><p>Location: Downy mildew is found throughout Ohio.</p><p>Time of infection: First symptoms may be seen on trifoliate leaves</p><p>of young plants in June during periods of high humidity and cool</p><p>temperatures. Disease spread continues if temperatures remain cool.</p><p>Most commonly found in years with above normal rainfall.</p><p>Management:</p><p>• Crop rotation</p><p>• Tillage</p><p>Note: Yield losses attributed to downy mildew are very minor and</p><p>none of the currently labeled fungicides are known to manage this</p><p>disease.</p><p>119</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>119</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>FROGEYE LEAF SPOT</p><p>Description: Frogeye leaf spot is caused by the fungus Cercospora</p><p>sojina, which infects new young leaves. Circular to irregular shaped</p><p>lesions form that are gray in the center and surrounded by a deep</p><p>purple ring. On the bottom side of the lesion on the underside of the</p><p>leaves, spores in the center of lesion can be seen.</p><p>Location: Frogeye is a residue-borne pathogen and can also be</p><p>carried by rain and wind. Typically damaging levels can only be</p><p>reached when susceptible varieties are planted into fields where the</p><p>disease was prevalent on soybeans the year before.</p><p>Time of infection: When inoculum is present, infections can occur</p><p>at any time of the season. In soybean fields that are continuous, and a</p><p>susceptible variety is grown, then infections can occur very early in the</p><p>season. If the pathogen is wind-blown, it is more often found at the late</p><p>R5/R6 growth stage.</p><p>Management:</p><p>• Resistant varieties</p><p>• Crop rotation</p><p>• If frogeye leaf spot is present on a susceptible variety at flowering, then</p><p>a fungicide application at R3 will protect yield.</p><p>120</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>120</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>POWDERY MILDEW</p><p>Description: Powdery mildew appears on the upper surface of leaves</p><p>as powdery tufts of mycelium.</p><p>Location: Rare but can occur wherever soybeans are grown.</p><p>Time of infection: First symptoms are seen on young leaves in mid-</p><p>to late July during periods of high humidity and cool temperatures.</p><p>Management:</p><p>• Resistant varieties</p><p>• Crop rotation</p><p>121</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>121</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>CERCOSPORA LEAF BLIGHT</p><p>Description: Purple to reddish discoloration on the upper surface of</p><p>leaves. May be in patches scattered around the field.</p><p>Location: Rare but more prevalent in southern Ohio.</p><p>Time of infection: In Ohio, when symptoms have developed, it has</p><p>occurred late in the growing season.</p><p>Management:</p><p>• Resistant varieties</p><p>• Manage residue through crop rotation or tillage</p><p>122</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>122</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>STEM AND LATE SEASON DISEASES</p><p>BROWN STEM ROT</p><p>Description: Leaf symptoms of brown stem rot consist of interveinal</p><p>chlorosis and necrosis where the veins remain green. The most reliable</p><p>characteristic is the dark, reddish brown discoloration of the stem pith</p><p>in the lower stem. Leaves may suddenly wilt and plants die three to four</p><p>weeks prior to maturity.</p><p>Location: Brown stem rot is more prevalent in fields with a long history</p><p>of soybean cultivation. Studies from Wisconsin have also shown that</p><p>soybeans grown in soils with a low pH have greater expression of</p><p>disease severity.</p><p>Time of infection: The brown stem rot fungus resides in the soil and</p><p>generally attacks plants during the first half of the growing season.</p><p>No obvious symptoms develop on plants until after flowering then</p><p>symptoms develop rapidly during periods of dry weather.</p><p>Management:</p><p>• Maintain best soil management practices with optimum pH</p><p>• Resistant varieties</p><p>• Crop rotation</p><p>Leaf Pith</p><p>123</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>123</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>CHARCOAL ROT</p><p>Description:</p><p>Charcoal rot has been</p><p>diagnosed more</p><p>frequently in Ohio</p><p>following several</p><p>summers of drought-</p><p>like conditions. Early</p><p>season diagnosis is</p><p>very difficult but during</p><p>the later stages of</p><p>plant development</p><p>very small, black</p><p>resistant structures (sclerotia)</p><p>become evident as a grayish-black</p><p>discoloration in the root and lower stem tissues. Cutting the lower stem</p><p>with a knife will expose the discolored tissues in comparison to the</p><p>normally healthy white tissues of healthy plants.</p><p>Location: This disease is more prevalent in southern Ohio than in the</p><p>northwest region.</p><p>Time of infection: Infection occurs early in the season in seedlings</p><p>and the fungus grows slowly in the plant until hot dry weather occurs</p><p>after flowering. Premature death of the plants suffering from drought</p><p>stress is an indication of charcoal rot.</p><p>Management:</p><p>• Crop rotation</p><p>• Plant at lower plant populations to reduce drought stress</p><p>• Maintain adequate soil fertility</p><p>124</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>124</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>SCLEROTINIA STEM ROT OR WHITE MOLD</p><p>Description: Sclerotinia stem rot is identified as a white cottony mold</p><p>growth on soybean stems after flowering. As the cottony growth ages,</p><p>hard, black oval to elongate resistant structures (sclerotia) form on the</p><p>stem surface or inside the stem. The sclerotia are gray to pinkish white</p><p>on the inside with a black outer surface.</p><p>Location: Sclerotinia stem rot occurs throughout the state, but has</p><p>been more severe in fields surrounded by woods with high plant</p><p>populations and high fertility.</p><p>Time of infection: Wet weather before and during flowering of the</p><p>soybean plant is important for infection. The duration of the wet period</p><p>during flowering and the capacity of the soybean canopy to keep</p><p>stems wet for extended periods of time contribute to disease severity.</p><p>Symptoms first appear in late August or early September.</p><p>Management:</p><p>• Resistant varieties</p><p>• Fungicide applications as seed treatment and also at flowering</p><p>• No-till production</p><p>• Reduce plant populations</p><p>125</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>125</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>PHYTOPHTHORA STEM CANKER</p><p>Description: In adult plants a severe root rot develops which then</p><p>moves several nodes up the stem and girdles the plants. Plants can die</p><p>throughout the season and tend to be those with low levels of partial</p><p>resistance (also called field resistance).</p><p>Location: Phytophthora root rot is primarily a problem in the heavy</p><p>clay, poorly drained soils throughout Ohio. This disease has re-</p><p>emerged as a major pathogen of soybeans due to the adaptations by</p><p>the Phytophthora populations to all of the commonly deployed Rps</p><p>genes (Rps1a, Rps1c, Rps1k, and Rps3a) as well as fewer varieties with</p><p>high levels of partial resistance.</p><p>Time of infection: Plants of any age can be infected, and infections</p><p>occur when soils are saturated. The best time to see symptom</p><p>development is one to two weeks after a heavy rain.</p><p>Management:</p><p>• Choose varieties with high levels of partial resistance</p><p>• Improve drainage</p><p>126</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>126</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>STEM CANKER</p><p>Description: Stem canker begins as a reddish-brown lesion on the</p><p>leaf scar after the petiole on the stem has fallen. The lesion enlarges</p><p>rapidly forming a slightly sunken, reddish-brown to black girdling</p><p>canker. The stem above the canker generally dies. More recently, the</p><p>stem cankers lack clear margins and tops of plants are wilted. When</p><p>plants are cut open, the internal tissue is discolored.</p><p>Location: Stem canker can occur anywhere in Ohio on highly</p><p>susceptible varieties.</p><p>Time of infection: Lower stems may be affected early in the season,</p><p>but girdling occurs after mid-season such that dead plants can be</p><p>found in August.</p><p>Management:</p><p>• Resistant varieties</p><p>• Crop rotation</p><p>127</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>127</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>SUDDEN DEATH SYNDROME</p><p>Description: Leaf symptoms start as bright yellow, small spots which</p><p>grow to necrotic areas. The pith in the stem is white in contrast to</p><p>brown stem rot. For SDS the roots are rotted and the tissue in the root</p><p>crown is discolored and gray.</p><p>Location: SDS has been found throughout Ohio. In almost all cases,</p><p>SCN is also present at high levels.</p><p>Time of infection: Wet weather following planting is correlated with</p><p>higher incidence of disease.</p><p>Management:</p><p>• Reduce SCN populations</p><p>• Improve soil drainage</p><p>• Crop rotation</p><p>• Plant resistant varieties</p><p>• Fungicide seed treatments for the SDS fungus will protect against</p><p>early infections</p><p>128</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>128</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>POD AND STEM BLIGHT</p><p>PHOMOPSIS SEED ROT</p><p>Description—Pod and Stem Blight: Linear rows of small black</p><p>fruiting bodies (pycnidia) on stems of plants and scattered over the</p><p>surface of pods at or before harvest are signs of pod and stem blight.</p><p>Description—Phomopsis Seed Rot: Phomopsis seed rot can be</p><p>detected in harvested grain as badly cracked, shriveled, and moldy</p><p>seed.</p><p>Location: Pod and stem blight and Phomopsis seed rot occur</p><p>throughout Ohio, but are more prevalent in the southern and western</p><p>regions of the state.</p><p>Time of infection: The fungi that cause these diseases reside</p><p>on residues or on seed. Infection occurs during pod formation, but</p><p>symptoms do not develop until plants begin to mature and pods turn</p><p>yellow. Under wet conditions that prevent timely harvest of the crop,</p><p>the pod and stem blight fungi enter the developing seed and cause</p><p>Phomopsis seed rot.</p><p>Management:</p><p>• Crop rotation</p><p>• Fungicide seed treatments that target true fungi</p><p>• Tillage</p><p>Pod and Stem Blight Phomopsis Seed Rot</p><p>129</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>129</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>SOYBEAN CYST NEMATODE</p><p>Description: The most common symptom of soybean cyst nematode</p><p>is reduced yield with no above-ground plant symptoms. Yellowing and</p><p>stunting of plants is generally only detected in fields with high cyst</p><p>populations. The cyst nematode can best be seen on roots in the field</p><p>during late July or August. Plants should be dug to keep roots intact.</p><p>Gently remove soil from around roots and examine root surfaces for</p><p>very small (about the size of a shirt pin head), white cysts. Later in the</p><p>season cysts turn brown and are difficult to see. Soil samples should be</p><p>collected in the fall after harvest for disease management strategies.</p><p>Location: Soybean cyst nematode has been found in all soybean</p><p>production counties in Ohio.</p><p>Time of infection: Soybean cyst nematode can infect plants</p><p>throughout the growing season. The nematode is capable of several</p><p>generations during the growing season.</p><p>Management:</p><p>• Crop rotation among non-host crops (wheat-corn)</p><p>• Rotation among sources of cyst resistance (PI88788, Peking)</p><p>• Keep SCN populations low</p><p>130</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>130</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>VIRUS DISEASES OF SOYBEAN</p><p>BEAN POD MOTTLE VIRUS</p><p>Description: Bean pod mottle virus causes mild symptoms on</p><p>soybean ranging from very light mottling to a puckered appearance on</p><p>new leaves. Seed that develop on affected plants will be mottled. This</p><p>virus is transmitted by bean leaf beetles and other chewing insects.</p><p>Location: Very common virus disease of soybean.</p><p>Time of infection: More infections and greatest yield impact occur</p><p>when soybeans are infected early in the season. This tends to coincide</p><p>on first planted fields in early to mid-April. This coincides with the</p><p>emergence of the overwintering stage of the bean leaf beetle.</p><p>Management: Avoid planting food-grade or other varieties that</p><p>can be impacted by seed coat quality early. Monitor bean leaf beetle</p><p>populations. Manage weeds which can also serve as hosts or inoculum</p><p>reservoirs for the virus.</p><p>131</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>131</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>NUTRIENT DEFICIENCY SYMPTOMS</p><p>IN SOYBEAN</p><p>POTASSIUM</p><p>• Potassium deficiency symptoms appear as a chlorosis along the leaf</p><p>tip progressing toward the leaf base along the leaf margins.</p><p>• It can occur on both the older, lower leaves and the newer, upper</p><p>leaves. However, it will most likely show up more on the lower leaves.</p><p>132</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>132</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>NUTRIENT DEFICIENCY SYMPTOMS</p><p>IN</p><p>SOYBEAN (CONT.)</p><p>MANGANESE</p><p>• Manganese deficiency symptoms appear as an interveinal chlorosis</p><p>of newer, upper trifoliates.</p><p>• Can be confused with iron deficiency, but iron deficiency is quite</p><p>uncommon in Ohio.</p><p>• Manganese deficiency typically occurs on high organic matter soils,</p><p>soils with higher pH levels, and poorly drained soils.</p><p>• Drought conditions also induce manganese deficiency.</p><p>133</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>133</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>NUTRIENT DEFICIENCY SYMPTOMS</p><p>IN SOYBEAN (CONT.)</p><p>Nitrogen, phosphorus, and magnesium deficiency symptoms will show up</p><p>more on the lower, older leaves, whereas the others will be more likely</p><p>on the new growth.</p><p>NITROGEN</p><p>• Pale green or yellow leaves (fairly uniform discoloration).</p><p>• Look for poor nodulation on roots.</p><p>PHOSPHORUS</p><p>• Growth stunted, leaf cupping, and some discoloration possible.</p><p>• Deficiencies are rare in Ohio.</p><p>CALCIUM</p><p>• Leaf tips pinched, leaf bronzing, early leaf drop, growing point</p><p>goes necrotic.</p><p>• Deficiencies are rare in Ohio.</p><p>MAGNESIUM</p><p>• Pale green lower leaves with yellow mottled interveinal tissue, later</p><p>looks speckled bronze.</p><p>• Deficiencies are rare in Ohio (causes: sandy soils, low pH, high K).</p><p>SULFUR</p><p>• Stunted plants, pale green color, similar to nitrogen deficiency except</p><p>chlorosis may be more apparent on upper leaves.</p><p>• Most likely during cool wet conditions or on sandy soils.</p><p>IRON</p><p>• Same symptoms as manganese (also a problem in high pH and/or</p><p>dry soils).</p><p>• Deficiencies are rare in Ohio.</p><p>134</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>134</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>NUTRIENT DEFICIENCY SYMPTOMS</p><p>IN SOYBEAN (CONT.)</p><p>BORON</p><p>• Small seed, poor quality.</p><p>• No deficiencies have been documented in Ohio.</p><p>• Toxicity can occur at low pH, symptoms include yellowing to browning</p><p>of leaf margins, crinkled leaves and leaf edges that cup up or down</p><p>(can stunt plant).</p><p>COPPER</p><p>• No deficiency symptoms are visible.</p><p>• Deficiencies are rare in Ohio.</p><p>ZINC</p><p>• Stunted plants with light green to yellow leaves (interveinal chlorosis),</p><p>lower leaves may turn bronze and drop.</p><p>• Scarce flowers, malformed pods, slow maturation.</p><p>MOLYBDENUM</p><p>• Molybdenum is necessary for nitrogen fixation, symptoms are the same</p><p>as nitrogen deficiency.</p><p>CHLORINE</p><p>• Toxicity: necrosis along the leaf margin, leaves shed prematurely, occurs</p><p>most frequently during reproductive stages.</p><p>135</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>135</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>NUTRIENT SUFFICIENCY RANGES</p><p>FOR SOYBEANS</p><p>Upper fully developed leaf sampled prior to initial flowering</p><p>Nutrient Element Unit Sufficient</p><p>Nitrogen (N) % 4.25–5.50</p><p>Phosphorus (P) % 0.30–0.50</p><p>Potassium (K) % 2.01–2.50</p><p>Calcium (Ca) % 0.36–2.00</p><p>Magnesium (Mg) % 0.26–1.00</p><p>Sulfur (S) % 0.21–0.40</p><p>Manganese (Mn) ppm 21–100</p><p>Iron (Fe) ppm 51–350</p><p>Boron (B) ppm 21–55</p><p>Copper (Cu) ppm 10–30</p><p>Zinc (Zn) ppm 21–50</p><p>Molybdenum (Mo) ppm 1.0–5.0</p><p>Sampling information on page 244.</p><p>136</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>136</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>OHIO FERTILIZER</p><p>RECOMMENDATIONS IN POUNDS</p><p>PER ACRE (P2O5 AND K2O) FOR</p><p>SOYBEAN WHEN SOIL TESTS ARE IN</p><p>THE MAINTENANCE RANGE*</p><p>Yield Goal (bu/acre)</p><p>Soybean</p><p>crop</p><p>removal</p><p>42 50 58 67 75 83</p><p>P2O5</p><p>0.80 lb/bu</p><p>33 40 47 53 60 67</p><p>K2O</p><p>1.08 lb/bu</p><p>45 54 63 72 81 90</p><p>Notes:</p><p>Updated recommendations are based on work to update the Tri-State Fertilizer</p><p>Recommendations coordinated by Steve Culman, 2014-2018, in over 200 on-</p><p>farm trials for P and K.</p><p>*Maintenance range for P (M3) is 20 to 40 ppm. Maintenance range for K (M3)</p><p>is 100 to 150 ppm. If soil test levels above maintenance range, then no nutrient</p><p>application (P and K) is needed. Sample and retest every three to four years.</p><p>If P level is below the critical level, then make an annual application. An</p><p>alternative is to apply 50 percent additional P2O5 every other year. Resample</p><p>and test regularly every three to four years. Band application of P2O5 can be</p><p>beneficial when P test is below maintenance range.</p><p>If CEC is very low or very high an annual K2O application may be warranted.</p><p>Low is below 6 meq/100g and high is above 25 meq/100g. Resample and test</p><p>regularly every three to four years.</p><p>Adapted from Tri-State Fertilizer Recommendations for Corn, Soybeans, Wheat</p><p>and Alfalfa.</p><p>Pennsylvania producers, see the Penn State Extension soil testing website:</p><p>agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks/agronomic.</p><p>http://agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks/agronomic</p><p>137</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>137</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>SOYBEAN STAND EVALUATION AND</p><p>REPLANT DECISIONS</p><p>Yield Effects from Reduced Plant Populations, Uniform</p><p>Stand and Weed-free Conditions</p><p>Population Yield as % of normal</p><p>Plants/acre Conventional Till No-till</p><p>160,000 100 100</p><p>120,000 100 98</p><p>80,000 98 95</p><p>60,000 90 90</p><p>Yield Effects from Delayed Planting (Uniform Stands)</p><p>Planting Date Yield % of Normal</p><p>May 1 100</p><p>May 10 99</p><p>May 20 96</p><p>May 30 90</p><p>June 10 80</p><p>June 20 68</p><p>June 30 57</p><p>July 10 40</p><p>138</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>138</p><p>S</p><p>oy</p><p>be</p><p>an</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>SOYBEAN STAND EVALUATION AND</p><p>REPLANT DECISIONS (CONT.)</p><p>Expected Yield Loss from Defoliation</p><p>Development Stage</p><p>at Defoliation</p><p>Defoliation %</p><p>10 25 50 75 100</p><p>% Yield Loss</p><p>V2 0 3 4 5 18</p><p>V6 0 3 5 8 26</p><p>R2 2 4 9 15 37</p><p>R4 7 13 18 36 83</p><p>R6 6 6 7 14 33</p><p>R7 0 0 0 0 0</p><p>NOTE: See page 90 for vegetative and reproductive staging.</p><p>Soybean Population as a Function of Hula Hoop</p><p>Diameter</p><p>Hoop Diameter (inches) Multiplier</p><p>28 10,200</p><p>30 8,900</p><p>32 7,800</p><p>34 6,900</p><p>36 6,200</p><p>Plant Population by Length of Row to Represent</p><p>1/1000th of an Acre</p><p>Row Width</p><p>(inches)</p><p>Length of Row Multiplier</p><p>7.5 69 feet, 8 inches 1,000</p><p>15 34 feet, 10 inches 1,000</p><p>30 17 feet, 5 inches 1,000</p><p>139</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>139</p><p>S</p><p>oybean M</p><p>anagem</p><p>ent</p><p>ESTIMATING SOYBEAN YIELD</p><p>1. Count the number of pod-bearing plants in 1/1000th of an acre.</p><p>7.5-inch rows—count plants in 69 feet, 8 inches of row.</p><p>15-inch rows—count plants in 34 feet, 10 inches of row.</p><p>30-inch rows—count plants in 17 feet, 5 inches of row.</p><p>Number of plants in 1/1000th acre________</p><p>2. Estimate pods per plant by counting the number of pods (containing</p><p>one or more seeds) from 10 plants.</p><p>Plant 1 Plant 6</p><p>Plant 2 Plant 7</p><p>Plant 3 Plant 8</p><p>Plant 4 Plant 9</p><p>Plant 5 Plant 10</p><p>Total pod numbers (Add up total pods from 10 plants) ___________</p><p>Average pods/plant (Total pod number divided by 10 plants) __________</p><p>3. Estimated number of seeds per pod by counting number of seeds from</p><p>10 pods selected at random. Generally, number of seeds per pod is 2.5,</p><p>but this number can be less in stressful environmental conditions.</p><p>Pod 1 Pod 6</p><p>Pod 2 Pod 3</p><p>Pod 3 Pod 8</p><p>Pod 4 Pod 9</p><p>Pod 5 Pod 10</p><p>Total seed numbers (Add up total seeds from 10 plants) ___________</p><p>Average seeds/pod (Total seed number divided by 10 plants) ___________</p><p>4. Estimate number of seeds per pound (seed size). Assume 3,000 seeds</p><p>per pound. Soybean size can vary from 2,500 to 3,500 seeds per pound</p><p>depending on growing conditions. If the soybean plant experienced</p><p>stress, seed size may be smaller (more seeds per pound). Use a seed</p><p>size estimate of 3,500 seeds per pound if smaller seeds are expected</p><p>because of late-season stress. Under ideal seed filling conditions, seed</p><p>sizes may reach 2,500 seeds per pound.</p><p>bushels/acre=[(plants/1,000th acre) x (pods/plant) x (seeds/pod)] /</p><p>[(seeds/pound) x 0.06]</p><p>*Results are more accurate later in the growing season.</p><p>*Results are more accurate if this calculation is done in several areas of</p><p>the field.</p><p>140</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>140</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>WHEAT MANAGEMENT</p><p>141</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>141</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>141</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>WHEAT GROWTH STAGES</p><p>St</p><p>ag</p><p>e</p><p>1</p><p>On</p><p>e</p><p>sh</p><p>oo</p><p>t</p><p>St</p><p>ag</p><p>e</p><p>2</p><p>Ti</p><p>lle</p><p>rin</p><p>g</p><p>be</p><p>gi</p><p>ns</p><p>St</p><p>ag</p><p>e</p><p>3</p><p>Ti</p><p>lle</p><p>rs</p><p>fo</p><p>rm</p><p>ed</p><p>St</p><p>ag</p><p>e</p><p>4</p><p>Le</p><p>af</p><p>sh</p><p>ea</p><p>th</p><p>s</p><p>st</p><p>re</p><p>ng</p><p>th</p><p>en</p><p>St</p><p>ag</p><p>e</p><p>5</p><p>Le</p><p>af</p><p>sh</p><p>ea</p><p>th</p><p>s</p><p>st</p><p>ro</p><p>ng</p><p>ly</p><p>er</p><p>ec</p><p>te</p><p>d</p><p>St</p><p>ag</p><p>e</p><p>6</p><p>Fi</p><p>rs</p><p>t n</p><p>od</p><p>e</p><p>of</p><p>s</p><p>te</p><p>m</p><p>vi</p><p>planting date and temperatures since</p><p>planting. It is useful to know when the crop emerged, but if you do not</p><p>you can estimate that event also. Corn emergence typically requires 100</p><p>to 150 GDDs.</p><p>Corn leaf developmental rates may be characterized by two phases.</p><p>From emergence to V10 (10 visible leaf collars), leaf emergence occurs</p><p>approximately every 82 GDDs. From V10 to tasseling, leaf collar emergence</p><p>occurs more rapidly at approximately one leaf every 50 GDDs. Previously,</p><p>about 60 to 65 GDDs were associated with the appearance of new leaf</p><p>collars during vegetative growth.</p><p>Example (from reference noted below): A field was planted on</p><p>April 28, but you do not know exactly when it emerged. Since planting,</p><p>approximately 785 GDDs have accumulated. If you assume that the crop</p><p>emerged in about 120 GDDs, then the estimated leaf stage for the crop</p><p>would be about V8. This estimate is calculated by first subtracting 120</p><p>from 785 to account for the estimated thermal time to emergence, then</p><p>dividing the result (665) by 82 (equal to 8.1).</p><p>These predictions of leaf stage development are only estimates. The</p><p>existence of other growth-limiting stresses and conditions (nutrient</p><p>deficiencies, compaction, etc.) may influence the accuracy of these</p><p>estimates.</p><p>Reference</p><p>Nielsen, R.L. 2008. Use Thermal Time to Predict Leaf Stage Development</p><p>in Corn Corny News Articles, Purdue Univ. [Online]. Available at agry.</p><p>purdue.edu/ext/corn/news/timeless/vstageprediction.html (URL verified</p><p>9/27/18)</p><p>http://agry.purdue.edu/ext/corn/news/timeless/vstageprediction.html</p><p>http://agry.purdue.edu/ext/corn/news/timeless/vstageprediction.html</p><p>8</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>8</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>INFORMATION REQUIRED TO MAKE</p><p>A CORN REPLANTING DECISION</p><p>Replant decisions in corn should be based on strong evidence that the</p><p>returns to replanting will not only cover replant costs but also net enough</p><p>to make it worth the effort.</p><p>Specific information needed to determine if replanting is justified:</p><p>• Original target plant population/intended plant stand</p><p>• Plant stand after damage</p><p>• Uniformity of plant stand after damage</p><p>• Original planting date</p><p>• Possible replanting date</p><p>• Likely replanting pest control and seed costs</p><p>AFTER-DAMAGE PLANT POPULATION</p><p>To estimate after-damage plant population per acre, count the number of</p><p>viable plants in a length of row that equals 1/1000 of an acre and multiply</p><p>by 1000. See the table on page 268 that shows row length needed for</p><p>various row widths. Make several counts in different rows in different parts</p><p>of the field. Six to eight counts per 20 acres should be sufficient.</p><p>After-Damage Stand Uniformity</p><p>When making plant counts, note skips or gaps visible in the row. Was</p><p>average length more or less than 3 feet? Gaps of 4 to 6 feet can cut yields</p><p>about 5 percent.</p><p>Should You Patch-In a Poor Stand?</p><p>• If you replant within two weeks of planting the original, patching-in</p><p>may be a viable option. Yields will be similar to those from a uniform-</p><p>emerging replanted stand, if you can get relatively uniform plant spacing</p><p>within the row between the old and new plants. Within two weeks of</p><p>planting, it is often too early to determine what the final stand will be</p><p>(and whether patching will be needed).</p><p>• If you replant within three weeks after the initial planting, yield potential</p><p>is about 10 percent greater if you tear up the field and start over with</p><p>an even emerging stand rather than just patch-in the original stand.</p><p>Balance this possible yield increase against the additional cost of tillage,</p><p>seed, and dryer fuel.</p><p>• If one-half or more of the plants in the stand emerge three weeks late</p><p>or later, then replanting may increase yields by up to 10 percent. To</p><p>decide whether to replant in this situation, estimate both the expected</p><p>economic return of the increased yield compared to your replanting</p><p>costs and the risk of emergence problems with the replanted stand.</p><p>9</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>9</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>Should late emerging plants be protected during</p><p>row cultivation?</p><p>• If the delayed plants emerge only one to two weeks late, use shields</p><p>and avoid burying the late emergers during cultivation.</p><p>• Protect plants emerging three weeks late if one-half or more of the</p><p>plants in the stand are late emergers.</p><p>• If less than one-quarter of the stand emerges three weeks late or later, it</p><p>will probably not pay to encourage their survival. Yields will be about the</p><p>same whether or not these delayed plants are buried during cultivation.</p><p>Source: National Corn Handbook. Chapter 36, “Effects of Uneven Seedling</p><p>Emergence in Corn.”</p><p>Grain Yields for Corn Planted at Various Dates and</p><p>Populations, Expressed as a Percent of Optimum</p><p>Planting Date and Population</p><p>Planting Date</p><p>Plants per acre at harvest (X 1000)</p><p>10 15 20 25 30 35</p><p>% of optimum yield</p><p>April 10 62 76 86 92 94 93</p><p>April 20 67 81 91 97 99 97</p><p>April 30 68 82 92 98 100 98</p><p>May 9 65 79 89 95 97 96</p><p>May 19 59 73 84 89 91 89</p><p>May 29 49 63 73 79 81 79</p><p>Adapted from: Nafziger, 1994. J. Prod. Ag. 7:59–62</p><p>How to use this table: The table shows the effect of planting date and</p><p>plant population on final grain yield. Grain yields for varying dates and</p><p>populations are expressed as a percentage of the yield obtained at the</p><p>optimum planting date and population. This table has been modified</p><p>to provide estimates of potential yield losses for planting dates in</p><p>early June (online at agry.purdue.edu/ext/corn/news/articles.08/</p><p>DelayedPltUpdate-0523.html).</p><p>A farmer planted on April 30 at a seeding rate sufficient to attain a harvest</p><p>population of 30,000 plants per acre. On May 29 stand was reduced to</p><p>16,000 plants per acre as a result of saturated soil conditions and ponding.</p><p>According to the table, the expected yield for the existing stand would be</p><p>84 percent of the optimum. If the corn crop was planted the next day on</p><p>May 30, and produced a full stand of 30,000 plants per acre, the expected</p><p>yield would be 81 percent of the optimum. The difference expected from</p><p>replanting would be negative (81 minus 84, or minus 3 percentage points)</p><p>and indicate no advantage to replanting.</p><p>http://agry.purdue.edu/ext/corn/news/articles.08/DelayedPltUpdate-0523.html</p><p>http://agry.purdue.edu/ext/corn/news/articles.08/DelayedPltUpdate-0523.html</p><p>10</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>10</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>Importance of plant distribution within the row: Values in this</p><p>replant chart are based on a uniform distribution of plants within the row.</p><p>Add a 5 percent yield loss penalty if the field assessment reveals several</p><p>gaps of 4-6 feet within rows and a 2 percent penalty for gaps of 1-3 feet.</p><p>The following are additional online sources of information on making</p><p>replant decisions:</p><p>Nielsen, R. L. 2008. More thoughts on late planting. Corny News Network,</p><p>Purdue Extension. [Online]. Available at agry.purdue.edu/ext/corn/news/</p><p>articles.08/delayedpltupdate-0523.html.</p><p>Thomison, P. R. 1992. Guidelines for Corn Replant Decisions. OSU Extension.</p><p>Available at agcrops.osu.edu/newsletter/corn-newsletter/2017-13/corn-</p><p>replant-decisions-some-tips-consider.</p><p>http://agry.purdue.edu/ext/corn/news/articles.08/delayedpltupdate-0523.html</p><p>http://agry.purdue.edu/ext/corn/news/articles.08/delayedpltupdate-0523.html</p><p>http://agcrops.osu.edu/newsletter/corn-newsletter/2017-13/corn-replant-decisions-some-tips-consider</p><p>http://agcrops.osu.edu/newsletter/corn-newsletter/2017-13/corn-replant-decisions-some-tips-consider</p><p>11</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>11</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>ASSESSING FLOODING AND</p><p>PONDING DAMAGE TO CORN</p><p>The extent to which flooding injures corn is determined by several factors</p><p>including: (1) plant stage of development when flooding occurs; (2) duration</p><p>of flooding; and (3) air/soil temperatures. Prior to the V6 stage (six visible</p><p>leaf collars) or when the growing point is at or below the soil surface, corn</p><p>can generally survive only two to four days of flooded conditions. The</p><p>oxygen supply in the soil is depleted after</p><p>si</p><p>bl</p><p>e</p><p>St</p><p>ag</p><p>e</p><p>7</p><p>Se</p><p>co</p><p>nd</p><p>no</p><p>de</p><p>vi</p><p>si</p><p>bl</p><p>e</p><p>St</p><p>ag</p><p>e</p><p>8</p><p>La</p><p>st</p><p>le</p><p>af</p><p>ju</p><p>st</p><p>v</p><p>is</p><p>ib</p><p>le</p><p>St</p><p>ag</p><p>e</p><p>10</p><p>In</p><p>b</p><p>oo</p><p>t</p><p>St</p><p>ag</p><p>e</p><p>9</p><p>Li</p><p>gu</p><p>le</p><p>o</p><p>f l</p><p>as</p><p>t</p><p>le</p><p>af</p><p>ju</p><p>st</p><p>vi</p><p>si</p><p>bl</p><p>e</p><p>St</p><p>ag</p><p>e</p><p>10</p><p>.1</p><p>St</p><p>ag</p><p>e</p><p>10</p><p>.5</p><p>flo</p><p>w</p><p>er</p><p>in</p><p>g</p><p>St</p><p>ag</p><p>e</p><p>11</p><p>Ti</p><p>lle</p><p>rin</p><p>g</p><p>St</p><p>em</p><p>e</p><p>xt</p><p>en</p><p>si</p><p>on</p><p>He</p><p>ad</p><p>in</p><p>g</p><p>Ri</p><p>pe</p><p>ni</p><p>ng</p><p>142</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>142</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>WHEAT STAND EVALUATION</p><p>Wheat Stand in Million Plants/Acre, Plants/ft2, and</p><p>Plants/Foot Row by Row Width</p><p>7.5-inch row width 15-inch row width</p><p>Million</p><p>plants/acre</p><p>Plants/ft2 Plants/foot</p><p>row</p><p>Plants/ft2 Plants/foot</p><p>row</p><p>1.0 23 14 23 29</p><p>1.1 25 16 25 32</p><p>1.2 28 17 28 34</p><p>1.3 30 19 30 37</p><p>1.4 32 20 32 40</p><p>1.5 34 22 34 43</p><p>1.6 37 23 37 46</p><p>1.7 39 24 39 49</p><p>1.8 41 26 41 52</p><p>1.9 44 27 44 55</p><p>2.0 46 29 46 57</p><p>143</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>143</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>143</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>FREEZE DAMAGE</p><p>The extent of freeze damage to winter wheat primarily depends on</p><p>three factors: wheat growth stage, temperature, and duration of</p><p>freezing temperature. There also may be small differences among</p><p>cultivars, but this is usually due to slight differences in growth stage.</p><p>Prior to Feekes 6.0 growth stage, we expect minimal damange to</p><p>wheat after freezing temperatures.</p><p>At the joining stage through ligule of flag leaf</p><p>visible (Feekes 6.0 through 9.0) wheat should</p><p>be able to tolerate temperatures of 24 degrees</p><p>Fahrenheit for two hours. Symptoms of freeze</p><p>damage at these stages include leaf yellowing</p><p>or burning, lesions, and bending of lower</p><p>stems. Flag leaves may also become twisted.</p><p>Twisted flag leaves may also be a result of 2,4-D</p><p>herbicide damage.</p><p>At the boot stage (Feekes 10.0), wheat should</p><p>be able to tolerate a temperature of 28 degrees</p><p>Fahrenheit for two hours. Damage at the boot</p><p>stage includes sterility, the head being trapped</p><p>in the boot, damage to the lower stem, and leaf</p><p>discoloration. Bent heads are not necessarily a</p><p>sign of freeze damage as they may also be the</p><p>result of rapid growth with warm temperatures,</p><p>followed by slower growth with low temperatures.</p><p>Heading and flowering (Feekes 10.1-10.5.3) are</p><p>the most sensitive growth stages. Two hours at 30</p><p>degrees Fahrenheit can result in severe yield loss</p><p>due to sterility. Flowering begins near the center of</p><p>the wheat spike (Feekes 10.5.1), followed by the top</p><p>(Feekes 10.5.2), and then bottom (Feekes 10.5.3).</p><p>Depending on the flowering stage, sterility may only</p><p>occur on part of the spike. Freeze damage symptoms</p><p>include white awns or white spikes, damage to the</p><p>lower stem, and leaf discoloration. After freezing,</p><p>the anthers are white and shriveled instead of the</p><p>normal light green or yellow color.</p><p>144</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>144</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>INSECT SCOUTING CALENDAR FOR</p><p>WHEAT</p><p>Pest Sep/Oct April May June</p><p>Hessian Fly</p><p>Cereal Leaf Beetle</p><p>Common or True Armyworm</p><p>Cereal Aphid</p><p>145</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>145</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>145</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>WHEAT PESTS</p><p>HESSIAN FLY</p><p>Identification and Incidence: Lodging and stem breakage of</p><p>wheat in the early summer plus the presence of flaxseeds (puparia</p><p>of the fly) near the joints are primary indicators of Hessian fly injury,</p><p>which also causes stunted growth and thin stands. Life cycle includes</p><p>two generations per year, of which adults of the second generation</p><p>conclude egg laying between late September and early October in</p><p>Ohio.</p><p>Sampling and Assessment: Wheat fields should be scouted in June</p><p>to determine presence or absence of problem.</p><p>Management Options: Primary cultural practice for preventing</p><p>problem is planting wheat in the fall after fly-free dates. Use of resistant</p><p>varieties should be emphasized. Wheat sown on or after the date</p><p>indicated for each county will escape most egg deposition by the fall</p><p>brood of Hessian fly.</p><p>September</p><p>October</p><p>22 22</p><p>23</p><p>24</p><p>26</p><p>27</p><p>29</p><p>29</p><p>28</p><p>27</p><p>26</p><p>28</p><p>29</p><p>28</p><p>29</p><p>30</p><p>1</p><p>2</p><p>3</p><p>3 4 4</p><p>3</p><p>2</p><p>1</p><p>21</p><p>30 30</p><p>1</p><p>3</p><p>23</p><p>22</p><p>25 25</p><p>23</p><p>22</p><p>23 23</p><p>24</p><p>23</p><p>23</p><p>22</p><p>23</p><p>24</p><p>26 26</p><p>28</p><p>25</p><p>27</p><p>28</p><p>29</p><p>29</p><p>26</p><p>27</p><p>28</p><p>28</p><p>2424</p><p>22</p><p>23</p><p>26</p><p>262626</p><p>24</p><p>26</p><p>3</p><p>5</p><p>4</p><p>3</p><p>2</p><p>1</p><p>30</p><p>1</p><p>2</p><p>30 30</p><p>29</p><p>30</p><p>30</p><p>30</p><p>29</p><p>28</p><p>27</p><p>27</p><p>28</p><p>3</p><p>Ohio</p><p>146</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>146</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>HESSIAN FLY (CONT’D)</p><p>2</p><p>6</p><p>2</p><p>6</p><p>2</p><p>6</p><p>2</p><p>8</p><p>2</p><p>8</p><p>1 1</p><p>2</p><p>6</p><p>2</p><p>0</p><p>2</p><p>6</p><p>2</p><p>6</p><p>2</p><p>7</p><p>2</p><p>6</p><p>2</p><p>6</p><p>2</p><p>7</p><p>30</p><p>30 30</p><p>30</p><p>2</p><p>7</p><p>2</p><p>7</p><p>2</p><p>6</p><p>2</p><p>6 2</p><p>7</p><p>2</p><p>7</p><p>2</p><p>7</p><p>2</p><p>7</p><p>1</p><p>2</p><p>72</p><p>7</p><p>2</p><p>5</p><p>2</p><p>7</p><p>2</p><p>7</p><p>2</p><p>7</p><p>1</p><p>1</p><p>1 1 1</p><p>30</p><p>2</p><p>7</p><p>2</p><p>7</p><p>1</p><p>1</p><p>2</p><p>7</p><p>2</p><p>7</p><p>2</p><p>7</p><p>2</p><p>6</p><p>2</p><p>8</p><p>2</p><p>8</p><p>2</p><p>8</p><p>2</p><p>8</p><p>2</p><p>8</p><p>2</p><p>7</p><p>2</p><p>7</p><p>1</p><p>1</p><p>1</p><p>2</p><p>8</p><p>2</p><p>82</p><p>8</p><p>2</p><p>6</p><p>2</p><p>2</p><p>2</p><p>7</p><p>30</p><p>2</p><p>7</p><p>2</p><p>7</p><p>Se</p><p>pt</p><p>em</p><p>be</p><p>r</p><p>O</p><p>ct</p><p>ob</p><p>er</p><p>P</p><p>en</p><p>ns</p><p>yl</p><p>va</p><p>ni</p><p>a</p><p>147</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>147</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>147</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>HESSIAN FLY DEVELOPMENTAL CHART</p><p>(Adapted from: USDA Farmers’ Bulletin 1627, 1953)</p><p>148</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>148</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>CEREAL APHIDS</p><p>Identification and Incidence: Aphids commonly found on Ohio</p><p>wheat are English grain aphid (EGA) and Bird cherry oat aphid (BCOA).</p><p>Greenbug has not been identified as a pest of small grains in Ohio,</p><p>although it does affect Ohio turfgrass. EGA and BCOA may occur</p><p>in significant numbers, but rarely cause economic injury warranting</p><p>treatment.</p><p>Sampling: Evaluation of an infestation should include a random</p><p>inspection of numerous heads to determine average incidence.</p><p>Presence of insect predators, which often control infestations, should</p><p>be noted.</p><p>Economic Threshold: Rescue treatment is warranted if an average of</p><p>50 aphids are found per linear foot of row on small plants in the fall, or</p><p>100 per linear foot of row in the spring.</p><p>Management Options: Heavy aphid infestations, lacking predator</p><p>activity, may warrant rescue treatment. For more information, visit</p><p>aginsects.osu.edu and extension.psu.edu/publications/agrs-026.</p><p>Aphids</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>149</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>149</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>149</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>COMMON OR TRUE ARMYWORM</p><p>Identification and Incidence: The larva is green to brown and has</p><p>stripes on each side of its body. Full grown larvae are almost 1½ inches</p><p>in length. Larvae feed at night and hide in the soil debris during the day.</p><p>Sampling: Sample several areas of the wheat field and count the</p><p>number of larvae per row foot collecting several larvae to make a size</p><p>determination.</p><p>Economic Threshold: A rescue treatment is warranted if six or more</p><p>armyworm larvae are found per 1 foot of row or if head cutting occurs</p><p>prior to flowering. Where larvae are abundant enough to justify action,</p><p>treatment should be applied when larvae are in the early stage of</p><p>development.</p><p>Management Options: There are a number of natural enemies that</p><p>may keep the armyworm in check. Check for these natural enemies</p><p>before any treatment is applied. For more information, visit aginsects.</p><p>osu.edu and extension.psu.edu/publications/agrs-026.</p><p>Larva</p><p>http://aginsects.osu.edu</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>150</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>150</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>CEREAL LEAF BEETLE</p><p>Identification and Incidence: Cereal leaf beetle (CLB) larvae may</p><p>defoliate small grain foliage in the spring. Black larvae are coated with</p><p>a slimy substance that readily spots a field inspector’s clothing. Heavily</p><p>infested fields will exhibit a frosted appearance. Oats can also be</p><p>severely injured by CLB.</p><p>Sampling: Evaluation of an infested field should include sampling of</p><p>30 or more plants to determine number of larvae per stem and stage</p><p>of larval development. Early larvae are less than 1/4 inch, late larvae are</p><p>approximately 3/8 inch prior to pupating.</p><p>Economic Threshold: An average of two or more larvae per stem</p><p>may be regarded as economic especially if larvae are feeding on the</p><p>flag leaf prior to head emergence. Damage later in head filling does not</p><p>appear to be that significant and if adults are seen late in spring, it is</p><p>likely too</p><p>late to manage this pest.</p><p>Management Options: CLB is generally controlled by a complex</p><p>of beneficial wasps. Treatment of fields may be warranted when mild</p><p>winters adversely affect natural control. For more information, visit</p><p>aginsects.osu.edu and extension.psu.edu/publications/agrs-026.</p><p>Adult Larva</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>151</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>151</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>151</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>TIME OF DISEASE OCCURRENCE</p><p>ON WHEAT</p><p>D</p><p>is</p><p>ea</p><p>se</p><p>Se</p><p>p</p><p>O</p><p>ct</p><p>N</p><p>ov</p><p>D</p><p>ec</p><p>Ja</p><p>n</p><p>Fe</p><p>b</p><p>M</p><p>ar</p><p>A</p><p>pr</p><p>M</p><p>ay</p><p>Ju</p><p>ne</p><p>Ju</p><p>l</p><p>Po</p><p>w</p><p>de</p><p>ry</p><p>M</p><p>ild</p><p>ew</p><p>Se</p><p>pt</p><p>or</p><p>ia</p><p>T</p><p>rit</p><p>ic</p><p>i B</p><p>lo</p><p>tc</p><p>h</p><p>St</p><p>ag</p><p>on</p><p>os</p><p>po</p><p>ra</p><p>N</p><p>od</p><p>or</p><p>um</p><p>B</p><p>lo</p><p>tc</p><p>h</p><p>Le</p><p>af</p><p>R</p><p>us</p><p>t</p><p>Fu</p><p>sa</p><p>riu</p><p>m</p><p>H</p><p>ea</p><p>d</p><p>B</p><p>lig</p><p>ht</p><p>(S</p><p>ca</p><p>b)</p><p>B</p><p>un</p><p>t o</p><p>r S</p><p>tin</p><p>ki</p><p>ng</p><p>S</p><p>m</p><p>ut</p><p>Lo</p><p>os</p><p>e</p><p>Sm</p><p>ut</p><p>W</p><p>he</p><p>at</p><p>Y</p><p>el</p><p>lo</p><p>w</p><p>M</p><p>os</p><p>ai</p><p>c</p><p>B</p><p>ar</p><p>le</p><p>y</p><p>Ye</p><p>llo</p><p>w</p><p>D</p><p>w</p><p>ar</p><p>f</p><p>C</p><p>ep</p><p>ha</p><p>lo</p><p>sp</p><p>or</p><p>iu</p><p>m</p><p>S</p><p>tr</p><p>ip</p><p>e</p><p>Ta</p><p>ke</p><p>-a</p><p>ll</p><p>Ro</p><p>ot</p><p>R</p><p>ot</p><p>Sh</p><p>ar</p><p>p</p><p>Ey</p><p>es</p><p>po</p><p>t</p><p>152</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>152</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>DISEASE ASSESSMENT KEYS FOR</p><p>DETERMINING SEVERITY BASED ON</p><p>PERCENTAGE OF SPIKE AND LEAF</p><p>AREA DISEASED</p><p>Stagonospora Glume Blotch Stagonospora Leaf</p><p>Blotch</p><p>10 25 50 1 5 25 50</p><p>Percentage Spike Area Covered Percentage Leaf Area</p><p>Covered</p><p>153</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>153</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>153</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>DISEASE ASSESSMENT KEYS FOR</p><p>DETERMINING SEVERITY BASED</p><p>ON PERCENTAGE OF LEAF AREA</p><p>DISEASED</p><p>Powdery Mildew Leaf Rust</p><p>1 5 10 15 20 25 1 5 10 15 20</p><p>Percentage Leaf Area Covered Percentage Leaf Area Covered</p><p>154</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>154</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>WHEAT DISEASES</p><p>POWDERY MILDEW</p><p>Description: Powdery mildew is recognized as small, white, powdery</p><p>pustules scattered over the leaves and stems, and occasionally on the</p><p>spikes of more susceptible varieties. As leaves age, small black fruiting</p><p>bodies (clistothecia) develop within the white pustules.</p><p>Location: Throughout Ohio, but more damaging in southern and north</p><p>central areas.</p><p>Time of attack: Powdery mildew can be seen on seedlings of early</p><p>planted wheat in the fall. Disease spread occurs in the spring when</p><p>temperatures increase to 60 degrees Fahrenheit or above, but spread</p><p>stops at temperatures above 80 degrees Fahrenheit.</p><p>Management:</p><p>• Resistant varieties</p><p>• Delayed planting</p><p>• Crop rotation</p><p>• Foliar fungicide application when two to three lesions present on leaf</p><p>below flag leaf</p><p>Photos: Wenjing Ling</p><p>155</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>155</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>155</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>SEPTORIA TRITICI LEAF BLOTCH</p><p>Description: Septoria tritici leaf blotch can be seen on the lower</p><p>leaves as irregular, reddish brown blotches. As lesions age, the centers</p><p>become bleached turning ash-white. Small black fruiting bodies</p><p>(pycnidia) develop within lesion centers.</p><p>Location: Septoria tritici leaf blotch occurs more frequently in western</p><p>and northwestern Ohio than in other regions of the state.</p><p>Time of attack: Lesions are first detected on the lower leaves in early</p><p>spring. During extended periods of cool (60-70 degrees Fahrenheit)</p><p>wet weather, the disease will spread to the upper leaves of the wheat</p><p>crop.</p><p>Management:</p><p>• Resistant varieties</p><p>• Crop rotation</p><p>• Till residues</p><p>• Foliar fungicide application when one to two lesions present on leaf</p><p>below flag leaf</p><p>156</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>156</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>STAGONOSPORA LEAF AND GLUME BLOTCH</p><p>Description: Stagonospora</p><p>nodorum leaf blotch begins</p><p>as small chocolate-brown</p><p>spots that enlarge into</p><p>lens-shaped lesions with</p><p>dark brown margins. As</p><p>the season progresses, the</p><p>lesions coalesce giving the</p><p>leaf a blotchy appearance.</p><p>Some wheat varieties develop</p><p>dark brown centers in the tan</p><p>leaf lesions. Glume blotch</p><p>occurs on the wheat heads as</p><p>irregular brown blotches on</p><p>the glumes, usually starting</p><p>near the tips of the glumes.</p><p>Location: Widespread</p><p>throughout Ohio.</p><p>Time of attack:</p><p>Stagonospora nodorum</p><p>attacks wheat in mid- to late</p><p>May and June during rainy</p><p>periods when temperatures</p><p>begin to warm (68-80 degrees</p><p>Fahrenheit).</p><p>Management:</p><p>• Resistant varieties</p><p>• Crop rotation</p><p>• Delay planting</p><p>• Foliar fungicide application</p><p>when one to two lesions</p><p>present on leaf below flag</p><p>leaf</p><p>Photos: Jorge Salgado</p><p>157</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>157</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>157</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>LEAF RUST (BROWN OR ORANGE RUST)</p><p>Description: Leaf rust is recognized as small oval, orange-red</p><p>pustules scattered over the upper leaves of wheat plants.</p><p>Location: Leaf rust can be found throughout the state in years</p><p>favorable for disease spread. However, the disease generally spreads</p><p>from southwest to northeast Ohio.</p><p>Time of attack: Leaf rust spreads up from southern wheat-growing</p><p>areas with frequent light rains during late May and June.</p><p>Management:</p><p>• Resistant varieties</p><p>• Foliar fungicide application when five to 10 pustules present on flag leaf</p><p>Photo: Wenjing Ling</p><p>158</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>158</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>STRIPE RUST (YELLOW RUST)</p><p>Description: Small (relative to leaf rust), yellowish-orange pustules</p><p>neatly arranged in stripes on leaves and leaf sheaths. On highly</p><p>susceptible varieties, pustules may also develop on the glumes of the</p><p>head (spike).</p><p>Location: Stripe rust can develop anywhere in the state but tends to</p><p>be most prevalent in areas with cool, wet conditions.</p><p>Time of attack: Plants may be infected at any time during the growing</p><p>season. However, since the disease is driven primarily by spores</p><p>blowing up from southern states, stripe rust is usually seen in Ohio after</p><p>heading.</p><p>Management:</p><p>• Resistant varieties</p><p>• Foliar fungicide</p><p>159</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>159</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>159</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>LEAF RUST VERSUS STRIPE RUST</p><p>Leaf rust Stripe rust</p><p>Pustule appearance Large, round to ovoid,</p><p>scattered or clustered</p><p>on the upper surface</p><p>of leaves.</p><p>Small, elongated,</p><p>arranged in rows</p><p>forming stripes on</p><p>leaves.</p><p>Pustule color Orangish-red Yellowish-orange</p><p>Pustule location Mainly on leaves</p><p>and leaf sheaths, but</p><p>occasionally spikes</p><p>may also be affected.</p><p>Mainly on leaves,</p><p>but leaf sheaths and</p><p>spikes may also be</p><p>affected.</p><p>Optimum conditions Warm (77 to 86 F) and</p><p>rainy/humid.</p><p>Cool (50 to 64 F) and</p><p>rainy/humid.</p><p>Leaf Rust</p><p>Stripe Rust</p><p>160</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>160</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>FUSARIUM HEAD BLIGHT OR HEAD SCAB</p><p>Description: Head scab is identified as dead, bleached-out florets on</p><p>affected heads scattered throughout the field. Generally only a portion</p><p>of the florets die whereas other florets on the head remain green.</p><p>During periods of high humidity, salmon-pink colored spores form</p><p>on the margin of glumes of individual florets. Towards the end of the</p><p>season, small black fruiting bodies (perithecia) may develop on affected</p><p>heads. Seed from affected heads are lightweight and shriveled, with a</p><p>white to pinkish coloration, and are contaminated with vomitoxin.</p><p>Location: Throughout Ohio.</p><p>Time of attack: Wheat plants are most susceptible during the</p><p>flowering stage of the plant (late May to early June). Wet, warm weather</p><p>during this time generally means high disease levels.</p><p>Management:</p><p>• Resistant varieties</p><p>• Crop rotation with non-cereal crop</p><p>• Do not plant wheat after corn</p><p>• Till residues</p><p>• Integrated management with resistant varieties, triazole-based</p><p>fungicide, crop rotation, and tillage</p><p>161</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>161</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>161</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>BUNT OR STINKING SMUT</p><p>Description: Diseased heads have more open florets due to smutted</p><p>kernels. Affected kernels or bunt balls are dark colored and break open</p><p>releasing a soft, black, pasty mass of smut spores. Heads and diseased</p><p>kernels have a distinctive fishy odor.</p><p>Location: Not common, but can occur anywhere in Ohio, especially in</p><p>fields planted with untreated seeds.</p><p>Time of attack: Bunt is seed-borne</p><p>and effectively controlled with</p><p>seed treatments. Symptoms appear at heading and disease kernels</p><p>can be detected in June during grain fill.</p><p>Management:</p><p>• Seed treatment</p><p>162</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>162</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>LOOSE SMUT</p><p>Description: The kernels and florets of loose smut affected heads are</p><p>converted to a mass of black, sooty fungal spores. After the diseased</p><p>head emerges, the spores are blown away by the wind, leaving the</p><p>rachis of the head bare.</p><p>Location: Not common, but can occur anywhere in Ohio, especially in</p><p>fields planted with untreated seeds.</p><p>Time of attack: Loose smut is seed-borne and effectively controlled</p><p>with seed treatments. Symptoms appear during heading of the crop in</p><p>late May.</p><p>Management:</p><p>• Seed treatment</p><p>163</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>163</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>163</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>WHEAT SPINDLE STREAK MOSAIC</p><p>Description: Symptoms appear on the upper leaves as light-green to</p><p>yellow dashes and short streaks. The discontinuous streaks are parallel</p><p>to leaf veins and taper at the ends to form chlorotic spindle shapes. The</p><p>symptoms begin to fade as temperatures rise in late spring. Plants with</p><p>this viral disease are scattered throughout the field.</p><p>Location: This soil-borne viral disease has been found throughout the</p><p>state.</p><p>Time of attack: Symptoms first appear in the fall on highly susceptible</p><p>varieties, which appear yellow compared to resistant varieties. In the</p><p>spring leaf symptoms begin to be recognizable in mid-April and are</p><p>evident by early May.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Improve soil drainage</p><p>164</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>164</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>BARLEY YELLOW DWARF</p><p>Description: This virus disease is transmitted by aphids coming up</p><p>from the south. Plants infected in the fall are stunted and leaf symptoms</p><p>appear yellow to reddish or even purple. Plants infected in the spring</p><p>are usually not stunted, but the upper leaves turn yellow with purple to</p><p>red leaf margins. Affected leaves may lose their flexuous appearance</p><p>and become erect with sharp pointed tips.</p><p>Location: Barley yellow dwarf occurs throughout Ohio.</p><p>Time of attack: Infections in the fall are most serious on early planted</p><p>wheat. Spring infections are more common, but yield losses are</p><p>proportional to the percentage of plants affected in the field.</p><p>Management:</p><p>• Delay planting until after the Hessian Fly safe date</p><p>165</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>165</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>165</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>CEPHALOSPORIUM STRIPE</p><p>Description: Typical symptoms on leaves occur during the wheat</p><p>jointing to heading growth stages. Typical symptoms include chlorotic,</p><p>interveinal stripes that extend the length of the leaf blade, or brown</p><p>stripes bordered by yellow stripes. The veins within stripes are dark</p><p>brown. Plants generally die prematurely and produce little grain.</p><p>Location: This disease can occur throughout Ohio, but appears to be</p><p>more severe in compacted, heavy soils low in pH.</p><p>Time of attack: The fungus sporulates and enters roots in the winter.</p><p>Leaf symptoms can be recognized in early spring before jointing, but</p><p>the typical stripes are not easily detected until jointing. Evidence of the</p><p>brown veins can be detected in prematurely killed plants.</p><p>Management:</p><p>• Crop rotation</p><p>• Till residues</p><p>• Improve drainage</p><p>• Adjust soil pH to 6.5-7.0</p><p>• Control perennial grass weeds</p><p>166</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>166</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>TAKE-ALL ROOT ROT</p><p>Description: Plants affected by take-all occur in patches in the</p><p>field. Affected plants are stunted, yellowed, have fewer tillers and</p><p>die prematurely. Prematurely killed plants have bleached-out heads</p><p>or white heads that appear in contrast to the green heads of healthy</p><p>plants. Diagnostic black, scurfy, mold symptoms occur on roots and</p><p>lower stems.</p><p>Location: Take-all may occur anywhere in Ohio. Fields with</p><p>quackgrass infestations or fields planted back to wheat with no rotation</p><p>are likely problem fields.</p><p>Time of attack: The fungus attacks young seedlings in the fall, but</p><p>symptoms are usually not seen until early spring when affected plants</p><p>remain yellow after spring green-up. Blackening of root systems can be</p><p>detected in late May and June.</p><p>Management:</p><p>• Crop rotation</p><p>• Till residues</p><p>• Adjust soil pH to 6.5-7.0</p><p>• Control perennial grass weeds</p><p>167</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>167</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>167</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>SHARP EYESPOT</p><p>Description: Lesions develop on lower stems in early to late spring.</p><p>Lesions are oval in shape, with white to pale straw colored centers</p><p>and dark brown borders. Stems of infected plants may die prematurely</p><p>producing white heads and they may lodge.</p><p>Location: Sharp eyespot can occur throughout Ohio. It is usually</p><p>associated with heavy soils with poor drainage that have saturated</p><p>conditions during the spring.</p><p>Time of attack: The disease is caused by a soil-borne fungus that is</p><p>present in most soils. It attacks plants during the cold wet periods of</p><p>early spring. Symptoms are easily detected in May and June.</p><p>Management:</p><p>• Improve soil drainage</p><p>• Crop rotation</p><p>168</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>168</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>WHEAT DISEASE THRESHOLDS FOR</p><p>FOLIAR FUNGICIDES</p><p>Wheat Growth Stage Disease Leaf* Disease</p><p>Level**</p><p>Flag leaf emergence GS8</p><p>to Boot (GS10)</p><p>Powdery</p><p>mildew</p><p>2 2–3 lesions</p><p>Flag leaf emergence GS8</p><p>to Boot (GS10)</p><p>Stagonospora</p><p>leaf blotch</p><p>2 1–2 lesions</p><p>Head emergence (GS10.1)</p><p>to flowering (GS10.5.1)</p><p>Stagonospora</p><p>leaf blotch</p><p>2 1–2 lesions</p><p>Head emergence (GS10.1)</p><p>to flowering (GS10.5.1)</p><p>Leaf rust 1 (flag) 5–10 pustules</p><p>*Leaf number counted from top leaf (flag leaf = leaf 1) down on the tiller.</p><p>**Disease level based on average of 30–50 tillers randomly collected throughout</p><p>the field.</p><p>169</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>169</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>169</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>NUTRIENT DEFICIENCY SYMPTOMS</p><p>IN WHEAT</p><p>NITROGEN</p><p>• Slow plant growth, general light green appearance, few tillers, short</p><p>heads.</p><p>• Yellow discoloration from the leaf tip down in the form of a “V,” starting</p><p>on oldest leaves first.</p><p>PHOSPHORUS</p><p>• Bluish green to purple color in the leaves and stems; affects lower</p><p>leaves first.</p><p>• Poor tillering and root development.</p><p>POTASSIUM</p><p>• Stunted plants and yellowing of leaf tips and leaf margins.</p><p>• Deficiencies will show up on older leaves first.</p><p>CALCIUM</p><p>• Young leaves become yellow and dry; head is stunted and imperfect.</p><p>• Deficiencies are rare in Ohio.</p><p>MAGNESIUM</p><p>• Oldest leaves lose green color, turn from yellow to brown, curl and die.</p><p>SULFUR</p><p>• Similar to nitrogen deficiency but more pronounced on younger leaves.</p><p>• Stunted plants, reduced tillering, yellow cast.</p><p>MANGANESE</p><p>• Shows up in young leaves first as an interveinal chlorosis.</p><p>• Severe cases exhibit elongated white streaks, the center of which may</p><p>turn brown and fall out.</p><p>170</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>170</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>NUTRIENT DEFICIENCY SYMPTOMS</p><p>IN WHEAT (CONT.)</p><p>IRON</p><p>• Young leaves develop interveinal chlorosis; veins remain green in the</p><p>early stages.</p><p>• Progresses rapidly and may turn the entire leaf white.</p><p>• Deficiencies are rare in Ohio.</p><p>BORON</p><p>• Irregularly shaped white spots between veins, which could develop</p><p>into stripes with a waxy, raised appearance.</p><p>• Discoloration found on youngest leaves first, starting at the base of the</p><p>leaf and progressing toward the tip.</p><p>COPPER</p><p>• Youngest leaves become yellow and stunted, eventually turning pale</p><p>while the old leaves die back.</p><p>• Dead leaf tissue may appear along the tips and leaf edges in a pattern</p><p>similar to potassium deficiency.</p><p>ZINC</p><p>• Light green to white streaks on either side of the midrib that may</p><p>develop into a broad band of bleached tissue most evident on lower</p><p>leaves.</p><p>• Leaf midribs and margins remain green.</p><p>• Sometimes leaf edges appear to be tinted red or brown.</p><p>MOLYBDENUM</p><p>• Light yellow young plants—similar to N deficiency.</p><p>• Wilted leaves; youngest</p><p>leaves may twist.</p><p>• Deficiencies are rare in Ohio.</p><p>171</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>171</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>171</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>NITROGEN RECOMMENDATIONS</p><p>FOR WHEAT BASED ON YIELD</p><p>POTENTIAL</p><p>Yield Potential Pounds N to apply</p><p>bu/acre lbs N/acre</p><p>50 40</p><p>70 75</p><p>90+ 110</p><p>1. Recommended N rate is based on the relationship:</p><p>N (lb/acre) = 40 + [1.75 x (yield potential – 50)]</p><p>2. No credits are made based on previous crop. Consult state recommendations</p><p>concerning credits for organic waste materials such as manure.</p><p>3. Apply 15 to 30 lb N/acre at planting and remainder near green-up in spring;</p><p>or, apply all N at planting as anhydrous ammonia plus a nitrification inhibitor,</p><p>injected on 15” or narrower spacing.</p><p>4. On high organic matter soils (greater than 20 percent organic matter) reduce</p><p>the N rate by 30 to 50 lb N/acre.</p><p>Wheat does not require large amounts of N until stem elongation (Feekes</p><p>Growth Stage 6), which is the middle or the end of April depending on</p><p>the location in state. Ohio research has shown no yield benefit from</p><p>applications made prior to this time period. Soil organic matter or N</p><p>applied at planting generally provides sufficient N for early growth until</p><p>stem elongation.</p><p>However, wet weather may prevent application of N at early stem</p><p>elongation. A practical compromise is to topdress N any time fields are</p><p>suitable for application after initial green-up to early stem elongation.</p><p>There is still a potential for loss even at green-up applications. To lessen</p><p>this risk a producer may want to use a N source that has the least potential</p><p>for loss for earlier applications.</p><p>Pennsylvania producers, see the Penn State Extension soil testing</p><p>website: agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks/</p><p>agronomic.</p><p>http://agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks/agronomic</p><p>http://agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks/agronomic</p><p>172</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>172</p><p>W</p><p>he</p><p>at</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>NUTRIENT SUFFICIENCY RANGES</p><p>FOR WHEAT</p><p>Upper leaves sampled prior to initial bloom</p><p>Nutrient Element Unit Sufficient</p><p>Nitrogen (N) % 2.59–4.00</p><p>Phosphorus (P) % 0.21–0.50</p><p>Potassium (K) % 1.51–3.00</p><p>Calcium (Ca) % 0.21–1.00</p><p>Magnesium (Mg) % 0.16–1.00</p><p>Sulfur (S) % 0.21–0.40</p><p>Manganese (Mn) ppm 16–200</p><p>Iron (Fe) ppm 11–300</p><p>Boron (B) ppm 6–40</p><p>Copper (Cu) ppm 6–50</p><p>Zinc (Zn) ppm 21–70</p><p>Sampling information on page 244.</p><p>173</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>173</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>173</p><p>W</p><p>heat M</p><p>anagem</p><p>ent</p><p>OHIO FERTILIZER</p><p>RECOMMENDATIONS IN</p><p>POUNDS PER ACRE (P2O5 AND</p><p>K2O) FOR WHEAT FOR GRAIN</p><p>WHEN SOIL TESTS ARE IN THE</p><p>MAINTENANCE RANGE*</p><p>Yield Goal (bu/acre)</p><p>Wheat</p><p>crop</p><p>removal</p><p>62.5 75 87.5 100 112.5 125</p><p>P2O5</p><p>0.49 lb/bu</p><p>31 37 43 49 55 61</p><p>K2O</p><p>0.24 lb/bu</p><p>15 18 21 24 27 30</p><p>Notes:</p><p>Updated recommendations are based on work to update the Tri-State Fertilizer</p><p>Recommendations coordinated by Steve Culman, over the years 2014 to 2018 in</p><p>over 200 on-farm trials for P and K.</p><p>*Maintenance range for P (M3) is 20 to 40 ppm. Maintenance range for K (M3)</p><p>is 100 to 150 ppm. If soil test levels above maintenance range, then no nutrient</p><p>application (P & K) is needed. Sample and retest every three to four years.</p><p>If P level is below the critical level, then make an annual application. An</p><p>alternative is to apply 50 percent additional P2O5 every other year. Resample</p><p>and test regularly every three to four years. Band application of P2O5 can be</p><p>beneficial when P test is below maintenance range.</p><p>Apply P2O5 in the year wheat planted if at lower end of maintenance range.</p><p>If CEC is very low or very high, an annual K2O application may be warranted.</p><p>Low is below 6 meq/100g and high is above 25 meq/100g. Resample and test</p><p>regularly every three to four years.</p><p>Pennsylvania producers, see the Penn State Extension soil testing website:</p><p>agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks/agronomic.</p><p>http://agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks/agronomic</p><p>174</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>174</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>FORAGE MANAGEMENT</p><p>175</p><p>Forage M</p><p>anagem</p><p>ent</p><p>175</p><p>Forage M</p><p>anagem</p><p>ent</p><p>GROWTH AND DEVELOPMENT</p><p>OF FORAGES</p><p>In order for a seed to germinate, adequate moisture, favorable</p><p>temperatures, and oxygen are all essential. With proper seed-to-soil</p><p>contact, seeds are able to absorb the essential amount of water necessary</p><p>to sprout (often referred to as imbibition), while the soil protects the seed</p><p>from drying out. A suitably prepared seedbed or appropriate seeding</p><p>depth in no-till establishment can help to ensure the necessary seed-to-</p><p>soil contact.</p><p>GRASSES</p><p>After the grass seed absorbs water, enzymes produced by the embryo</p><p>break down the endosperm and convert the starch into energy that can</p><p>be used for growth. The radicle—or primary root—emerges from the</p><p>embryo soon after water absorption, followed by the coleoptile—or shoot.</p><p>The coleoptile protects the first</p><p>leaf after germination, and as the</p><p>coleoptile grows and reaches the</p><p>soil surface, the first leaf emerges</p><p>through the protective sheath and</p><p>begins to elongate. As the leaf</p><p>grows, it begins to produce its</p><p>own food through photosynthesis,</p><p>and soon thereafter, a second</p><p>leaf emerges from the growing</p><p>point in the coleoptile. The leaves</p><p>produced as the plant grows will</p><p>all be developed from this growing</p><p>point.</p><p>As grass plants grow, they produce</p><p>tillers—or shoots—that branch from</p><p>the main plant crown.</p><p>176</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>176</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>Legumes</p><p>After the legume seed absorbs water, the radicle—which later becomes</p><p>the plant’s taproot—emerges from the embryo and becomes the primary</p><p>root for the growing legume plant, responsible for absorption and</p><p>anchoring.</p><p>At germination, the hypocotyl, which will serve as the stem, elongates and</p><p>breaks through the soil surface, pulling two cotyledons and epicotyl—or</p><p>growing point—above the surface of the soil. The first leaf, or unifoliate,</p><p>emerges from the epicotyl, which captures sunlight to convert to energy</p><p>through photosynthesis.</p><p>Following the first leaf emergence, the epicotyl continues to grow and</p><p>produce trifoliates, or 3-leaflet structures. As trifoliates continue to emerge,</p><p>secondary stems emerge from the axillary buds at the cotyledon nodes</p><p>and develop the crown of the plant at the soil surface.</p><p>Images: Lollato, R. P., & Min, D. (2017). Alfalfa Growth and Development. Manhattan, KS: Kansas State</p><p>University.</p><p>177</p><p>Forage M</p><p>anagem</p><p>ent</p><p>177</p><p>Forage M</p><p>anagem</p><p>ent</p><p>SCOUTING CALENDAR FOR</p><p>ALFALFA</p><p>In</p><p>se</p><p>ct</p><p>/D</p><p>is</p><p>ea</p><p>se</p><p>s</p><p>A</p><p>pr</p><p>il</p><p>M</p><p>ay</p><p>Ju</p><p>ne</p><p>Ju</p><p>ly</p><p>A</p><p>ug</p><p>us</p><p>t</p><p>Se</p><p>pt</p><p>O</p><p>ct</p><p>A</p><p>lfa</p><p>lfa</p><p>W</p><p>ee</p><p>vi</p><p>l</p><p>Po</p><p>ta</p><p>to</p><p>L</p><p>ea</p><p>fh</p><p>op</p><p>pe</p><p>r</p><p>M</p><p>ea</p><p>do</p><p>w</p><p>S</p><p>pi</p><p>ttl</p><p>eb</p><p>ug</p><p>A</p><p>ph</p><p>id</p><p>s</p><p>Ph</p><p>yt</p><p>op</p><p>ht</p><p>ho</p><p>ra</p><p>R</p><p>oo</p><p>t R</p><p>ot</p><p>Sc</p><p>le</p><p>ro</p><p>tin</p><p>ia</p><p>C</p><p>ro</p><p>w</p><p>n</p><p>an</p><p>d</p><p>St</p><p>em</p><p>R</p><p>ot</p><p>Le</p><p>pt</p><p>o</p><p>Le</p><p>af</p><p>S</p><p>po</p><p>t</p><p>Ve</p><p>rt</p><p>ic</p><p>ul</p><p>um</p><p>W</p><p>ilt</p><p>Sp</p><p>rin</p><p>g</p><p>B</p><p>la</p><p>ck</p><p>S</p><p>te</p><p>m</p><p>A</p><p>nt</p><p>hr</p><p>ac</p><p>no</p><p>se</p><p>178</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>178</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>FORAGE PESTS</p><p>ALFALFA WEEVIL</p><p>Identification and Incidence: Overwintering adult weevils become</p><p>active during the first warm days of spring and deposit eggs, which</p><p>hatch into larvae that may defoliate the first cutting. Larvae pass</p><p>through 4 instar stages ranging in size from 1/8 to 1/2 inch and then</p><p>pupate in a fibrous pupal case before transforming to adults. Life cycle</p><p>includes one generation per year in Ohio.</p><p>Sampling: A larval count is made by collecting 10 stems from a</p><p>location and shaking the stems in a bucket to dislodge the larvae. This</p><p>is repeated until 30 stems have been sampled.</p><p>Economic Threshold: Treatment is based on the stand height, tip</p><p>feeding and number of larvae per stem.</p><p>Action thresholds relevant to stand height, tip</p><p>feeding and density of larvae per stem</p><p>Stem Height</p><p>(Inches)</p><p>Indication of</p><p>Problem % Tip</p><p>Feeding</p><p>Larva</p><p>Sampled/</p><p>Stem</p><p>Action</p><p>Needed</p><p>6 25 1</p><p>Check in 7</p><p>days</p><p>9 50 > 1 Spray</p><p>12 75 > 2</p><p>Spray or</p><p>harvest</p><p>16 100 > 4 Harvest early</p><p>Management Options: If sampling indicates potential for economic</p><p>injury and alfalfa cannot be harvested early, rescue treatment is</p><p>warranted. Parasitic wasps and fungal diseases prevent weevils from</p><p>causing economic injury in most years. For more information, visit</p><p>aginsects.osu.edu and extension.psu.edu/publications/agrs-026.</p><p>Larvae Adult</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>179</p><p>Forage M</p><p>anagem</p><p>ent</p><p>179</p><p>Forage M</p><p>anagem</p><p>ent</p><p>POTATO LEAFHOPPER</p><p>Identification and Incidence: Migrating PLH populations become</p><p>established on alfalfa during the second cutting and may reduce yields</p><p>until late August. Foliar injury is indicated by yellowing of foliage,</p><p>termed hopperburn, and plants are stunted. Critical periods of injury</p><p>occur from late second cutting to early fourth cutting.</p><p>Sampling: Prediction of injury depends on detection of abundant PLH</p><p>presence prior to onset of foliar injury. Sweep net sampling is the most</p><p>effective method.</p><p>Economic Threshold: Potential for economic injury exists when</p><p>number of PLH per 10 sweeps exceeds height of stand expressed in</p><p>inches. Threshold may be increased during periods of vigorous growth</p><p>or decreased during periods of stand stress. Presence of PLH nymphs</p><p>in abundance indicates high potential for injury. Action thresholds for</p><p>resistant varieties are three times the thresholds for regular varieties.</p><p>Action thresholds for control of PLH</p><p>Stand Height</p><p>Inches</p><p>Alfalfa Tolerance for Stress</p><p>Low Medium High</p><p>Action Threshold of PLH/10 Sweeps</p><p>6 3 6 9</p><p>10 5 10 15</p><p>16 8 16 24</p><p>20+ 10 20 30</p><p>Management Options: Timely harvests will reduce PLH population</p><p>development and impact. New seedings are especially vulnerable</p><p>and should be monitored closely. The use of PLH resistant alfalfa is</p><p>an alternative to the use of foliar treatments, although they should be</p><p>watched closely during the establishment year. For more information,</p><p>visit aginsects.osu.edu and extension.psu.edu/publications/agrs-026.</p><p>Adult Nymph</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>180</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>180</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>ALFALFA DISEASES</p><p>PHYTOPHTHORA ROOT ROT</p><p>Description: Plants are stunted with yellow, red, or purple leaves.</p><p>Dark brown to black lesions occur on tap roots. Frequently the lower</p><p>portion of the tap root is rotted off immediately below the crown region.</p><p>Phytophthora also causes damping off, with seedlings failing to emerge</p><p>or collapsing at the soil surface.</p><p>Location: Phytophthora root rot occurs throughout Ohio. It is</p><p>especially severe on heavy, poorly drained soils. Symptoms are</p><p>frequently seen in low areas or between tile lines, while plants in drier</p><p>areas appear healthy.</p><p>Time of Attack: Infection can occur at any time during spring and</p><p>summer if the soil is water-saturated.</p><p>Management:</p><p>• Resistant varieties</p><p>• Seed treatment</p><p>• Improve soil drainage</p><p>181</p><p>Forage M</p><p>anagem</p><p>ent</p><p>181</p><p>Forage M</p><p>anagem</p><p>ent</p><p>SCLEROTINIA CROWN AND STEM ROT</p><p>Description: Soft mushy stems with masses of cottony growth are</p><p>clear signs of Sclerotinia crown and stem rot. Hard, black sclerotia, 1/8 to</p><p>1/4 inch in diameter form on diseased stems and crowns.</p><p>Location: The disease occurs throughout Ohio, but is most common</p><p>in late summer (August) seedings, especially when minimum tillage</p><p>methods are used.</p><p>Time of Attack: Infection by Sclerotinia takes place in the fall. Plants</p><p>die throughout the winter and spring, with symptoms most conspicuous</p><p>in April and early May. Symptoms are rarely seen after the first harvest.</p><p>Management:</p><p>• Early August or spring planting</p><p>• Till problem field before planting</p><p>182</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>182</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>LEPTO LEAF SPOT</p><p>Description: Leaf lesions begin as pinpoint-sized dark spots. Older</p><p>lesions are oval with tan centers and dark brown borders. Most lesions</p><p>are surrounded by a yellow “halo.” Heavily infected leaves turn brown</p><p>and drop.</p><p>Location: Lepto leaf spot occurs throughout Ohio.</p><p>Time of Attack: Infection can occur throughout the growing season</p><p>whenever foliage remains wet for an extended period.</p><p>Management:</p><p>• Resistant varieties</p><p>• Cut frequently</p><p>183</p><p>Forage M</p><p>anagem</p><p>ent</p><p>183</p><p>Forage M</p><p>anagem</p><p>ent</p><p>VERTICILLIUM WILT</p><p>Description: Symptoms usually do not become obvious until the third</p><p>year after seeding. Affected plants are scattered throughout a field.</p><p>Upper leaflets turn yellow or pink and often curl or twist. Stems are</p><p>stunted but remain erect.</p><p>Location: Verticillium wilt has been found in 17 counties in central and</p><p>northeastern Ohio. It has not been reported south of Interstate 70.</p><p>Time of Attack: Verticillium wilt usually spreads within a field and</p><p>to neighboring fields on infested harvesting equipment. Infection can</p><p>occur throughout the growing season.</p><p>Management:</p><p>• Resistant varieties</p><p>184</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>184</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>SPRING BLACK STEM</p><p>Description: Black lesions occur on lower leaves and stems. The</p><p>entire lower portion of the stem may be blackened and brittle. Heavily</p><p>infected leaves turn yellow and drop.</p><p>Location: Spring black stem occurs throughout Ohio.</p><p>Time of Attack: Infection takes place primarily during cool, wet</p><p>periods in the spring and fall. Most damage occurs in the spring, prior</p><p>to the first harvest.</p><p>Management:</p><p>• Monitor soil pH and fertility</p><p>• Frequent cutting</p><p>185</p><p>Forage M</p><p>anagem</p><p>ent</p><p>185</p><p>Forage M</p><p>anagem</p><p>ent</p><p>ANTHRACNOSE</p><p>Description: Diamond-shaped lesions occur near the base of the</p><p>stem. Lesions are tan with dark brown borders. Infected stems wilt,</p><p>producing the characteristic “shepherd’s crook” symptom. When</p><p>crowns are invaded, the inner tissues turn bluish-black and the plant</p><p>dies.</p><p>Location: Anthracnose occurs throughout Ohio on susceptible alfalfa</p><p>varieties.</p><p>Time of Attack: Anthracnose occurs during relatively hot weather,</p><p>from June through September. The spores are spread from plant to</p><p>plant by splashing rain or by means of infested harvesting equipment.</p><p>Management:</p><p>• Resistant varieties</p><p>186</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>186</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>DISEASES OF FORAGE GRASSES</p><p>Different diseases may impact forage grass production. A proper</p><p>identification of the disease is important given that several diseases</p><p>look similar. In general, the primary recommendation in cases of severe</p><p>infection by a forage grass disease is for early cutting of the forage,</p><p>rather than consider other treatment options; for example, the use of a</p><p>foliar fungicide.</p><p>RUSTS (CROWN, STEM, STRIPE, LEAF)</p><p>There are several different types of rust</p><p>that affect forage grasses. Differentiation</p><p>of rusts can be based on symptom type.</p><p>For example, for crown rust, look for</p><p>scattered, bright orange-yellow pustules</p><p>that develop on upper and lower leaf</p><p>surfaces. The pustules (uredinia) are</p><p>round to oval and may contain masses of</p><p>orange-yellow spores that are exposed</p><p>when the leaf epidermis ruptures. Uredia</p><p>may also be found on leaf sheaths. When</p><p>infection is severe, leaves turn pale yellow</p><p>and wither.</p><p>With stem rust, the epidermis is ruptured</p><p>by uredial pustules that will have orange-</p><p>red spore masses (urediospores). These</p><p>spore masses can be dispersed to other</p><p>plants. In mature plants, brown-black,</p><p>oblong to elongate telia form and this is</p><p>termed the black rust stage of the disease.</p><p>Stripe rust will have uredia that are lemon-</p><p>yellow in color that can be seen on both</p><p>sides of the leaf. Typically, long stripes will</p><p>form between the veins of the leaf. As the</p><p>season progresses, the pustules will turn</p><p>black in color as telia are produced.</p><p>Finally, with leaf rust, round to oval, yellow-</p><p>brown to red-brown pustules can form</p><p>on the upper leaf surface. Telia of the leaf</p><p>rust pathogen are rarely round later in the</p><p>growing season.</p><p>Leaf rust—</p><p>orchardgrass</p><p>Stem rust</p><p>Crown rust</p><p>187</p><p>Forage M</p><p>anagem</p><p>ent</p><p>187</p><p>Forage M</p><p>anagem</p><p>ent</p><p>POWDERY MILDEW</p><p>When conditions are cool</p><p>and damp,</p><p>it is common to see symptoms that</p><p>first appear as oblong, irregular, white,</p><p>powdery blotches on leaves. There may</p><p>be the presence of orange-yellow areas</p><p>beneath the blotches. As the colonies</p><p>enlarge, the entire leaf surface may be</p><p>covered with a grayish-white mycelium. In</p><p>severe infections, leaves will yellow and</p><p>then turn brown. Small, round black fruiting bodies (cleistothecia) may</p><p>be seen in the powdery mycelial tufts.</p><p>ERGOT</p><p>While most recognize the final phase</p><p>of symptom development, which are</p><p>the sclerotia that project out from the</p><p>inflorescence, symptoms first begin as</p><p>a sticky ooze that forms on the young</p><p>ovary. This ooze attracts insects and</p><p>will also form a substrate with other</p><p>microorganisms. This primary infection,</p><p>along with the development of sclerotium,</p><p>preempts ovary development. Ergot is more abundant in wet</p><p>growing seasons.</p><p>BROWN STRIPE</p><p>Favored by cooler,</p><p>wet weather, the</p><p>initial symptoms on</p><p>the foliage begin</p><p>as tiny, elliptical,</p><p>purplish-brown,</p><p>water-soaked</p><p>spots. These</p><p>spots will have a</p><p>dark brown board</p><p>that is visible on</p><p>both sides of the leaf. As the surrounding tissue becomes necrotic,</p><p>the lesions elongate for a brown streak. The size, shape, and color</p><p>of the lesion will depend on the host species and plant age. In older</p><p>lesions, the centers are ash-gray to almost white, and if conditions are</p><p>moist, small tufts of conidia can be seen. By the end of the growing</p><p>season, small black stromata form in a parallel arrangement, which is a</p><p>characteristic that can be used for identification.</p><p>Powdery mildew</p><p>Ergot</p><p>Brown stripe</p><p>188</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>188</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>SUMMER BLIGHT</p><p>Symptoms first appear as marginal, light</p><p>brown, irregular lesions that can be</p><p>approximately 0.6 inches long and 0.2</p><p>inches wide. When the infection is severe,</p><p>the lesions coalesce and can cover the</p><p>entire leaf. In the necrotic tissues, black</p><p>perithecia will form underneath the</p><p>epidermis. This disease is associated with</p><p>rainy conditions.</p><p>STAGONOSPORA LEAF</p><p>BLOTCH</p><p>Symptoms typically</p><p>begin as small,</p><p>blackish-brown to deep</p><p>purple spots that can</p><p>be elongated in shape.</p><p>In severe cases when</p><p>there are many lesions,</p><p>these coalesce,</p><p>which causes the leaf</p><p>to brown and die.</p><p>Browning often can</p><p>be seen developing</p><p>at the tip of the leaf or</p><p>along the margin and</p><p>form a long streak. One</p><p>sign of the pathogen</p><p>is small fruiting bodies (pycnidia) in dead areas of the leaf, which is</p><p>how the pathogen overwinters. Infection is favored by cool, wet spring</p><p>weather.</p><p>BARLEY YELLOW DWARF</p><p>BYDV infects many different cultivated and</p><p>wild grasses. Typical symptoms include</p><p>a yellow to reddish discoloration of the</p><p>foliage, often first observed at the leaf tip.</p><p>In severe cases, plants can be stunted.</p><p>BYDV can be confused with nutrient</p><p>deficiencies or plant stress, but serological</p><p>tests exist to identify the virus. Several</p><p>different aphid species are vectors of this</p><p>virus.</p><p>Photo: A. Tajimi, Japan</p><p>Summer Blight</p><p>Photos: Alyssa Collins</p><p>Stagonospora leaf blotch</p><p>Barley yellow dwarf</p><p>189</p><p>Forage M</p><p>anagem</p><p>ent</p><p>189</p><p>Forage M</p><p>anagem</p><p>ent</p><p>ALFALFA STAND EVALUATION</p><p>Evaluate the stand visually in early spring or fall by estimating the alfalfa</p><p>ground cover when the stand has 4 to 6 inches of new growth.</p><p>% Alfalfa Ground Cover Yield potential</p><p>> 80%, good vigor Excellent</p><p>60–80%, good vigor Fair to Good</p><p>40–60%, fair to poor vigor 60% of normal</p><p>20–40%, poor vigor < 50% of normal</p><p>Dig and count the alfalfa plants in a 2-square-foot area in several random</p><p>locations in the field. Split alfalfa roots lengthwise to observe tissue health.</p><p>Do not count plants having greater than 50 percent rot in roots and crowns.</p><p>Plant Density Guidelines Based on Stand Age</p><p>Year Minimum plants/ft2</p><p>Fall of seeding year 25–30</p><p>2nd 10–15</p><p>3rd or older 5–6</p><p>Healthy stands have less than 30 percent of plants showing significant</p><p>discoloration and rot in the crown and taproot, with vigorous crown shoots</p><p>symmetrically distributed around the crown. Weak stand with plants having</p><p>greater than 50 percent crown and root rot should be interseeded with</p><p>another legume or grass, or should be rotated to another crop.</p><p>190</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>190</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>ALFALFA RESEEDING GUIDELINES</p><p>• Recommendations for reseeding alfalfa stands differ by age of the</p><p>stand. This is because older alfalfa stands have a buildup of pathogens</p><p>and the plants release compounds that are toxic to new alfalfa seedlings</p><p>(autotoxicity).</p><p>RESEEDING IN THE FIRST YEAR</p><p>• Disk down or kill a seeding failure and reseed in late summer after a</p><p>spring seeding attempt, or the following spring after a late summer</p><p>seeding attempt. Autotoxicity is not a problem within the first year.</p><p>• Reseed gaps in the stand as soon as possible in the first year.</p><p>RESEEDING AFTER OLDER ALFALFA STANDS</p><p>• The best practice for long-term productivity is to rotate out of alfalfa</p><p>for at least a year.</p><p>• Do not interseed alfalfa to thicken a stand that is more than one year old.</p><p>Autotoxic compounds and competition from existing plants prevents</p><p>successful long-term stand improvement. Interseed another legume</p><p>or grass to lengthen life of the forage stand.</p><p>• If crop rotation is not a viable solution, kill the alfalfa stand in the fall</p><p>and seed alfalfa the next spring. Alternatively, kill the alfalfa stand in the</p><p>spring, rotate to a summer annual crop, and reseed to alfalfa in August.</p><p>• Research demonstrates that yields will be lower where the interval</p><p>between alfalfa stands is less than one year.</p><p>191</p><p>Forage M</p><p>anagem</p><p>ent</p><p>191</p><p>Forage M</p><p>anagem</p><p>ent</p><p>ESTIMATING ALFALFA QUALITY IN</p><p>THE FIELD</p><p>1. Choose a representative 2-square-foot area in the field. Determine</p><p>maturity of the most mature stem in the sampling area (vegetative,</p><p>bud, or flower).</p><p>2. Measure the length of the longest stem (from soil surface). Pull the stem</p><p>to its full length for an accurate measurement.</p><p>3. Use the chart on the next page to determine estimated neutral</p><p>detergent fiber (NDF) of the standing alfalfa crop.</p><p>• Example: Longest stem is 28 inches, most mature stem has buds;</p><p>NDF = 38 percent.</p><p>4. Repeat steps 1 through 3 in four or five representative areas across the</p><p>field and take the average.</p><p>NOTE: This procedure does not account for changes in quality due to</p><p>harvesting and storage. These factors may further raise NDF content by</p><p>three to six units or more. Therefore, begin harvesting when the NDF of</p><p>the standing forage is four to six units lower than the desired goal. Mixed</p><p>alfalfa-grass stands should be harvested even earlier.</p><p>This procedure is most accurate in healthy stands of pure alfalfa not</p><p>under stress.</p><p>Alfalfa early bud stage Alfalfa flower stage</p><p>192</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>192</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>ESTIMATING ALFALFA NDF IN FIELD</p><p>Length of</p><p>Tallest stem</p><p>(inches)</p><p>Stage of Most Mature Stem</p><p>Vegetative Bud Flower</p><p>% NDF</p><p>16 28.5 29.7 31.4</p><p>17 29.2 30.4 32.0</p><p>18 29.9 31.1 32.7</p><p>19 30.6 31.8 33.4</p><p>20 31.3 32.5 34.1</p><p>21 32.0 33.2 34.8</p><p>22 32.7 33.9 35.5</p><p>23 33.4 34.6 36.2</p><p>24 34.0 35.3 36.9</p><p>25 34.7 35.9 37.6</p><p>26 35.4 36.6 38.3</p><p>27 36.1 37.3 38.9</p><p>28 36.8 38.0 39.6</p><p>29 37.5 38.7 40.3</p><p>30 38.2 39.4 41.0</p><p>31 38.9 40.1 41.7</p><p>32 39.6 40.8 42.4</p><p>33 40.3 41.5 43.1</p><p>34 40.9 42.2 43.8</p><p>35 41.6 42.8 44.5</p><p>36 42.3 43.5 45.2</p><p>37 43.0 44.2 45.8</p><p>38 43.7 44.9 46.5</p><p>193</p><p>Forage M</p><p>anagem</p><p>ent</p><p>193</p><p>Forage M</p><p>anagem</p><p>ent</p><p>FORAGE HARVEST MANAGEMENT</p><p>Harvest timing is a compromise of forage yield, quality, persistence, and</p><p>the weather. The desired forage quality goal should be a primary guide</p><p>to harvest timing (see next page). Harvesting frequently at early maturity</p><p>provides high forage quality, but low yields. A good compromise in Ohio</p><p>and Pennsylvania is to cut in pre-flowering (bud/boot stages) to early</p><p>flower stages. This usually results in a 4-cut system.</p><p>Alfalfa mixtures with orchardgrass, perennial ryegrass, tall fescue, meadow</p><p>fescue, and reed canarygrass</p><p>can be harvested on a 4-cut schedule.</p><p>Cutting five times per season will increase forage quality, but will likely</p><p>reduce stand persistence, especially of legumes. When timothy or smooth</p><p>bromegrass are included in the stand, do not cut until the grass is in early</p><p>heading stage to prevent damage to the stand. These grasses are best</p><p>adapted to a 3-cut schedule.</p><p>Take the first cut in a timely manner whenever possible, because forage</p><p>quality declines quickly in the spring. Allow legumes to reach early to</p><p>mid-flowering stage during one summer growth cycle to improve stand</p><p>persistence. The preferred time to take this delayed cutting is in late</p><p>summer, because forage quality declines more slowly in late summer with</p><p>advancing maturity than it does earlier in the year.</p><p>FALL HARVEST CAUTIONS</p><p>Reduce winter injury risk by taking the last harvest by September 10.</p><p>Cutting in late September to mid-October disrupts accumulation of energy</p><p>and protein reserves in alfalfa taproots used for winter survival and spring</p><p>regrowth.</p><p>If fall cutting cannot be avoided, allow a growth interval of 45 days before</p><p>a fall harvest. A third cutting during the fall is less risky than a fourth or</p><p>fifth cutting. This should only be attempted on stands with optimal soil</p><p>pH and fertility, well-drained soils, and on stands that were not stressed</p><p>during the summer.</p><p>Cut after a killing frost (25 degrees Fahrenheit) in late October or early</p><p>November only on well-drained soils. Leave a 6-inch stubble. Late removal</p><p>of plant cover increases the risk of frost heaving on soils prone to heaving.</p><p>Do not fall harvest or graze a late summer seeding.</p><p>194</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>194</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>NUTRIENT DEFICIENCY SYMPTOMS</p><p>IN ALFALFA</p><p>NITROGEN</p><p>• Deficiency due to poor nodulation.</p><p>• Plant is stunted and has a light green appearance, rounded leaflets</p><p>with yellowing on tips.</p><p>• Firing on lower leaves first, develops into necrosis (brown tissue),</p><p>eventually leaves will fall off (abscise).</p><p>PHOSPHORUS</p><p>• Plants are dark green, spindly, and stunted.</p><p>• Petioles and leaflets are tilted upward, lower leaves may show firing.</p><p>• Stems may turn red.</p><p>• Reduced nodulation.</p><p>POTASSIUM</p><p>• Stunted plants.</p><p>• Yellow to white spots along leaf tips and margins.</p><p>• Potassium deficiency will show up on older leaves first.</p><p>CALCIUM</p><p>• Delayed emergence of primary leaves which, when emerged, may</p><p>appear cup shaped and necrotic.</p><p>• Chlorotic bands appear around the rest of the leaves.</p><p>• Terminal buds deteriorate and petioles break down.</p><p>MAGNESIUM</p><p>• Interveinal chlorosis in which the base and lower center of the leaf are</p><p>not affected.</p><p>• Downward curling of leaf margins and yellowing from the margin inward.</p><p>SULFUR</p><p>• Leaves including veins turn pale green to yellow.</p><p>• Young leaves are affected first.</p><p>• Terminal buds remain alive.</p><p>195</p><p>Forage M</p><p>anagem</p><p>ent</p><p>195</p><p>Forage M</p><p>anagem</p><p>ent</p><p>MANGANESE</p><p>• Interveinal chlorosis (not always distinct), buds remain alive.</p><p>• Spots of dead tissue appear on the leaves.</p><p>IRON</p><p>• Interveinal chlorosis, buds remain alive.</p><p>• Sharp color contrast between veins and the leaf.</p><p>• Spots of dead tissue appear on the leaves.</p><p>BORON</p><p>• Stunted growth, distortions at the tips or base of young leaves, terminal</p><p>bud is dead.</p><p>• Leaves near the growing point are yellowed and sometimes reddened,</p><p>while lower leaves appear healthy (sometimes confused with “hopper</p><p>burn”).</p><p>• Internodes are shortened, stems cracked, buds can be absent,</p><p>distorted, light brown in color or dead.</p><p>• Pink to whitish-yellow spots at leaf base.</p><p>COPPER</p><p>• Young leaves may wilt, wither, and shed without appearing chlorotic.</p><p>ZINC</p><p>• Growth is stunted.</p><p>• Interveinal chlorosis, brown spots, and dead tissue.</p><p>MOLYBDENUM</p><p>• See nitrogen deficiency (same deficiency symptoms).</p><p>196</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>196</p><p>Fo</p><p>ra</p><p>ge</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>NUTRIENT SUFFICIENCY</p><p>RANGES IN FORAGES</p><p>Prior to initial flowering; sampling information on page 252.</p><p>Nutrient Element Unit Alfalfa Grasses</p><p>Nitrogen (N) % 3.75–5.50 3.20-4.20</p><p>Phosphorus (P) % 0.25–0.70 0.23-0.35</p><p>Potassium (K) % 2.00–3.50 2.60-3.50</p><p>Calcium (Ca) % 1.75–3.00 0.50-0.90</p><p>Magnesium (Mg) % 0.30–1.00 0.10-0.30</p><p>Sulfur (S) % 0.25–0.50 0.20-0.25</p><p>Manganese (Mn) ppm 30–100 50-150</p><p>Iron (Fe) ppm 30–250 50-200</p><p>Boron (B) ppm 30–250 8-12</p><p>Copper (Cu) ppm 10–30 3-5</p><p>Zinc (Zn) ppm 20–70 20-50</p><p>Molybdenum (Mo) ppm 1.0–5.0 No data</p><p>197</p><p>Forage M</p><p>anagem</p><p>ent</p><p>197</p><p>Forage M</p><p>anagem</p><p>ent</p><p>OHIO FERTILIZER (P2O5 AND K2O)</p><p>RECOMMENDATIONS FOR ALFALFA</p><p>IN POUNDS PER ACRE1</p><p>Realistic Yield Goal (tons/acre)</p><p>Nutrient</p><p>Soil</p><p>Test</p><p>Level</p><p>M-3</p><p>(ppm)</p><p>3 4 5 6 7 8 9</p><p>P 20-40 39 52 65 78 91 104 117</p><p>K 100-150 150 200 250 300 300 300 300</p><p>Notes:</p><p>The above table shows recommendations for the optimal soil test levels of P and K.</p><p>1Adapted from 1995 Tri-State Fertilizer Recommendations for Corn, Soybeans,</p><p>Wheat, and Alfalfa. Crop removal rates for alfalfa are 13 pounds per ton for P2O5</p><p>and 50 pounds per ton for K2O. Sample and retest every three to four years.</p><p>A balanced P and K fertilization program is very important to maintain forage yields</p><p>and stand persistence. A seven-year study at Purdue University showed that alfalfa</p><p>stands receiving P fertilizer but not K fertilizer yielded less than stands that were</p><p>not fertilized at all. In fact, some of the plots receiving imbalanced fertilizer rates</p><p>experienced complete stand loss, while unfertilized plots and those provided low</p><p>rates of both P and K persisted.</p><p>The Purdue study showed highest alfalfa yields were routinely obtained with</p><p>applications of 50 pounds of P2O5 per acre per year and 300 pounds of K2O per</p><p>acre per year, or 100 pounds of P2O5 per acre per year and 200 pounds of K2O</p><p>per acre per year (extension.purdue.edu/extmedia/ay/ay-331-w.pdf).</p><p>In addition to P and K, sulfur may become limiting for alfalfa in some soils, primarily</p><p>in those with low organic matter that have received no manure. Tissue testing is the</p><p>best way to diagnose the need for sulfur (see page 194 for deficiency symptoms</p><p>and page 196 for tissue test sufficiency ranges for sulfur).</p><p>Pennsylvania producers, see the Penn State Extension soil testing website: agsci.</p><p>psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks/agronomic.</p><p>http://extension.purdue.edu/extmedia/ay/ay-331-w.pdf</p><p>http://agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks/agronomic</p><p>http://agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks/agronomic</p><p>198</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>198</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>WEED IDENTIFICATION</p><p>WEED SCOUTING</p><p>OVERVIEW</p><p>Purpose—Why scout for</p><p>weeds?</p><p>The first key to weed management</p><p>is proper weed identification.</p><p>The best method for timely</p><p>identification is through field</p><p>scouting. Furthermore, scouting</p><p>allows for additional information to</p><p>be collected in order to determine</p><p>if weed management programs are effective and if crop yield will be</p><p>impacted. See chart on next page.</p><p>What to document?</p><p>• ID and record all weeds found.</p><p>• Also, annually look for trends or new species & infestations.</p><p>• Determine the severity of infestation.</p><p>• Number/ft2 or 10+ feet of row.</p><p>• Sample areas should represent no more than 5 acres.</p><p>• Note height and growth stage of weeds and crop.</p><p>• Soil moisture observations.</p><p>• Can serve as indicators of herbicide effectiveness</p><p>• Adequate moisture is necessary for effective weed control</p><p>• Evaluation of herbicide effectiveness</p><p>• If weeds are present after an application, determine the reason</p><p>(various factors during application process? Resistance?, etc.)</p><p>• Crop injury from herbicides.</p><p>• Note kind of injury (stunting, yellowing, speckling, twisting, etc.)</p><p>• Crop stage at time of injury.</p><p>• Location in field (entire area, along edge, streaks, etc.).</p><p>199</p><p>W</p><p>eed Identification</p><p>199</p><p>W</p><p>eed Identification</p><p>WHEN TO SCOUT FOR WEEDS AND OTHER</p><p>WEED MANAGEMENT ISSUES.</p><p>C</p><p>ro</p><p>p</p><p>Ja</p><p>n-</p><p>M</p><p>ar</p><p>A</p><p>pr</p><p>M</p><p>ay</p><p>Ju</p><p>n</p><p>Ju</p><p>l</p><p>A</p><p>ug</p><p>Se</p><p>p</p><p>O</p><p>ct</p><p>N</p><p>ov</p><p>C</p><p>or</p><p>n/</p><p>So</p><p>yb</p><p>ea</p><p>n</p><p>Fa</p><p>ll</p><p>Se</p><p>ed</p><p>ed</p><p>Sm</p><p>al</p><p>l G</p><p>ra</p><p>in</p><p>Sp</p><p>rin</p><p>g</p><p>Se</p><p>ed</p><p>ed</p><p>Sm</p><p>al</p><p>l G</p><p>ra</p><p>in</p><p>Fa</p><p>ll</p><p>Se</p><p>ed</p><p>ed</p><p>Fo</p><p>ra</p><p>ge</p><p>Sp</p><p>rin</p><p>g</p><p>Se</p><p>ed</p><p>ed</p><p>Fo</p><p>ra</p><p>ge</p><p>Es</p><p>ta</p><p>bl</p><p>is</p><p>he</p><p>d</p><p>Fo</p><p>ra</p><p>ge</p><p>Ve</p><p>ge</p><p>ta</p><p>tio</p><p>n</p><p>Su</p><p>rv</p><p>ey</p><p>1-</p><p>2</p><p>W</p><p>B</p><p>P</p><p>(e</p><p>sp</p><p>. n</p><p>o-</p><p>til</p><p>l)</p><p>Ve</p><p>ge</p><p>ta</p><p>tio</p><p>n</p><p>Su</p><p>rv</p><p>ey</p><p>1-</p><p>2</p><p>W</p><p>B</p><p>P</p><p>(e</p><p>sp</p><p>. n</p><p>o-</p><p>til</p><p>l)</p><p>W</p><p>ee</p><p>d</p><p>Su</p><p>rv</p><p>ey</p><p>3-</p><p>6</p><p>W</p><p>A</p><p>P</p><p>W</p><p>ee</p><p>d</p><p>Su</p><p>rv</p><p>ey</p><p>3-</p><p>6</p><p>W</p><p>A</p><p>P</p><p>W</p><p>ee</p><p>d</p><p>Su</p><p>rv</p><p>ey</p><p>W</p><p>ee</p><p>d</p><p>Su</p><p>rv</p><p>ey</p><p>B</p><p>et</p><p>w</p><p>ee</p><p>n</p><p>C</p><p>ut</p><p>tin</p><p>gs</p><p>B</p><p>et</p><p>w</p><p>ee</p><p>n</p><p>C</p><p>ut</p><p>tin</p><p>gs</p><p>B</p><p>et</p><p>w</p><p>ee</p><p>n</p><p>C</p><p>ut</p><p>tin</p><p>gs</p><p>Ve</p><p>ge</p><p>ta</p><p>tio</p><p>n</p><p>Su</p><p>rv</p><p>ey</p><p>1-</p><p>2</p><p>W</p><p>B</p><p>P</p><p>(e</p><p>sp</p><p>. n</p><p>o-</p><p>til</p><p>l)</p><p>Ve</p><p>ge</p><p>ta</p><p>tio</p><p>n</p><p>Su</p><p>rv</p><p>ey</p><p>1-</p><p>2</p><p>W</p><p>B</p><p>P</p><p>(e</p><p>sp</p><p>. n</p><p>o-</p><p>til</p><p>l)</p><p>W</p><p>ee</p><p>d</p><p>Su</p><p>rv</p><p>ey</p><p>W</p><p>ee</p><p>d</p><p>Su</p><p>rv</p><p>ey</p><p>W</p><p>ee</p><p>d</p><p>Su</p><p>rv</p><p>ey</p><p>Pr</p><p>eh</p><p>ar</p><p>ve</p><p>st</p><p>W</p><p>ee</p><p>d</p><p>Su</p><p>rv</p><p>ey</p><p>Pr</p><p>eh</p><p>ar</p><p>ve</p><p>st</p><p>W</p><p>ee</p><p>d</p><p>Su</p><p>rv</p><p>ey</p><p>Ve</p><p>ge</p><p>ta</p><p>tio</p><p>n</p><p>Su</p><p>rv</p><p>ey</p><p>1-</p><p>2</p><p>W</p><p>B</p><p>P</p><p>(e</p><p>sp</p><p>. n</p><p>o-</p><p>til</p><p>l)</p><p>W</p><p>ee</p><p>d</p><p>Su</p><p>rv</p><p>ey</p><p>3-</p><p>6</p><p>W</p><p>A</p><p>P</p><p>Fi</p><p>na</p><p>l W</p><p>ee</p><p>d</p><p>Su</p><p>rv</p><p>ey</p><p>(p</p><p>rio</p><p>r t</p><p>o</p><p>fr</p><p>os</p><p>t)</p><p>W</p><p>ee</p><p>d</p><p>Su</p><p>rv</p><p>ey</p><p>•</p><p>3</p><p>-5</p><p>W</p><p>A</p><p>P</p><p>H</p><p>er</p><p>bi</p><p>ci</p><p>de</p><p>E</p><p>va</p><p>lu</p><p>at</p><p>io</p><p>n</p><p>W</p><p>ee</p><p>d</p><p>Su</p><p>rv</p><p>ey</p><p>3-</p><p>6</p><p>W</p><p>A</p><p>P</p><p>200</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>200</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>RELATIVE EMERGENCE OF COMMON WEEDS</p><p>OF SUMMER ANNUAL CROPS</p><p>Pr</p><p>ev</p><p>io</p><p>us</p><p>F</p><p>al</p><p>l</p><p>Ea</p><p>rly</p><p>S</p><p>pr</p><p>in</p><p>g</p><p>La</p><p>te</p><p>s</p><p>pr</p><p>in</p><p>g</p><p>W</p><p>in</p><p>te</p><p>r a</p><p>nn</p><p>ua</p><p>ls</p><p>a</p><p>nd</p><p>bi</p><p>en</p><p>ni</p><p>al</p><p>s</p><p>G</p><p>ro</p><p>up</p><p>0</p><p>G</p><p>ro</p><p>up</p><p>1</p><p>G</p><p>ro</p><p>up</p><p>2</p><p>G</p><p>ro</p><p>up</p><p>3</p><p>G</p><p>ro</p><p>up</p><p>4</p><p>G</p><p>ro</p><p>up</p><p>5</p><p>G</p><p>ro</p><p>up</p><p>6</p><p>G</p><p>ro</p><p>up</p><p>7</p><p>H</p><p>or</p><p>se</p><p>w</p><p>ee</p><p>d/</p><p>m</p><p>ar</p><p>es</p><p>ta</p><p>il</p><p>D</p><p>ow</p><p>ny</p><p>b</p><p>ro</p><p>m</p><p>e</p><p>Fi</p><p>el</p><p>d</p><p>pe</p><p>nn</p><p>yc</p><p>re</p><p>ss</p><p>Sh</p><p>ep</p><p>he</p><p>rd</p><p>'s</p><p>p</p><p>ur</p><p>se</p><p>B</p><p>ie</p><p>nn</p><p>ia</p><p>l t</p><p>hi</p><p>st</p><p>le</p><p>s</p><p>W</p><p>ild</p><p>c</p><p>ar</p><p>ro</p><p>t</p><p>D</p><p>an</p><p>de</p><p>lio</p><p>n</p><p>(fr</p><p>om</p><p>s</p><p>ee</p><p>d)</p><p>Fo</p><p>xt</p><p>ai</p><p>l b</p><p>ar</p><p>le</p><p>y</p><p>Ko</p><p>ch</p><p>ia</p><p>Pr</p><p>os</p><p>tr</p><p>at</p><p>a</p><p>kn</p><p>ot</p><p>w</p><p>ee</p><p>d</p><p>W</p><p>ild</p><p>m</p><p>us</p><p>ta</p><p>rd</p><p>D</p><p>an</p><p>de</p><p>lio</p><p>n</p><p>R</p><p>us</p><p>si</p><p>an</p><p>th</p><p>is</p><p>tle</p><p>W</p><p>hi</p><p>te</p><p>c</p><p>oc</p><p>kl</p><p>e</p><p>Q</p><p>ua</p><p>ck</p><p>gr</p><p>as</p><p>s</p><p>O</p><p>rc</p><p>ha</p><p>rd</p><p>gr</p><p>as</p><p>s</p><p>G</p><p>ia</p><p>nt</p><p>ra</p><p>gw</p><p>ee</p><p>d</p><p>P.</p><p>s</p><p>m</p><p>ar</p><p>tw</p><p>ee</p><p>d</p><p>La</p><p>dy</p><p>st</p><p>hu</p><p>m</p><p>b</p><p>C</p><p>.</p><p>la</p><p>m</p><p>bs</p><p>qu</p><p>ar</p><p>te</p><p>rs</p><p>W</p><p>ild</p><p>o</p><p>at</p><p>s</p><p>H</p><p>ai</p><p>ry</p><p>ni</p><p>gh</p><p>ts</p><p>ha</p><p>de</p><p>Sm</p><p>oo</p><p>th</p><p>b</p><p>ro</p><p>m</p><p>e</p><p>C</p><p>. r</p><p>ag</p><p>w</p><p>ee</p><p>d</p><p>W</p><p>oo</p><p>ly</p><p>cu</p><p>pg</p><p>ra</p><p>ss</p><p>Ve</p><p>lv</p><p>et</p><p>le</p><p>af</p><p>W</p><p>ild</p><p>bu</p><p>ck</p><p>w</p><p>he</p><p>at</p><p>C</p><p>an</p><p>ad</p><p>a</p><p>th</p><p>is</p><p>tle</p><p>G</p><p>ia</p><p>nt</p><p>fo</p><p>xt</p><p>ai</p><p>l</p><p>C</p><p>. c</p><p>oc</p><p>kl</p><p>eb</p><p>ur</p><p>Ye</p><p>llo</p><p>w</p><p>nu</p><p>ts</p><p>ed</p><p>ge</p><p>Re</p><p>dr</p><p>oo</p><p>t</p><p>pi</p><p>gw</p><p>ee</p><p>d</p><p>G</p><p>re</p><p>en</p><p>fo</p><p>xt</p><p>ai</p><p>l</p><p>C</p><p>. m</p><p>ilk</p><p>w</p><p>ee</p><p>d</p><p>H</p><p>em</p><p>p</p><p>do</p><p>gb</p><p>an</p><p>e</p><p>B</p><p>ar</p><p>ny</p><p>ar</p><p>dg</p><p>ra</p><p>ss</p><p>Ye</p><p>llo</p><p>w</p><p>fo</p><p>xt</p><p>ai</p><p>l</p><p>W</p><p>ild</p><p>p</p><p>ro</p><p>so</p><p>m</p><p>ill</p><p>et</p><p>Fi</p><p>el</p><p>d</p><p>sa</p><p>nd</p><p>bu</p><p>r</p><p>B</p><p>la</p><p>ck</p><p>N</p><p>ig</p><p>ht</p><p>sh</p><p>ad</p><p>e</p><p>Sh</p><p>at</p><p>te</p><p>rc</p><p>an</p><p>e</p><p>Ve</p><p>ni</p><p>ce</p><p>m</p><p>al</p><p>lo</p><p>w</p><p>W</p><p>at</p><p>er</p><p>he</p><p>m</p><p>p</p><p>S.</p><p>gr</p><p>ou</p><p>nd</p><p>ch</p><p>er</p><p>ry</p><p>J.</p><p>a</p><p>rt</p><p>ic</p><p>ho</p><p>ke</p><p>Fa</p><p>ll</p><p>pa</p><p>ni</p><p>cu</p><p>m</p><p>C</p><p>ra</p><p>bg</p><p>ra</p><p>ss</p><p>M</p><p>or</p><p>ni</p><p>ng</p><p>gl</p><p>or</p><p>ie</p><p>s</p><p>Ji</p><p>m</p><p>so</p><p>nw</p><p>ee</p><p>d</p><p>W</p><p>itc</p><p>hg</p><p>ra</p><p>ss</p><p>Pr</p><p>io</p><p>r t</p><p>o</p><p>cr</p><p>op</p><p>p</p><p>la</p><p>nt</p><p>in</p><p>g</p><p>A</p><p>bo</p><p>ut</p><p>th</p><p>e</p><p>tim</p><p>e</p><p>of</p><p>c</p><p>ro</p><p>p</p><p>pl</p><p>an</p><p>tin</p><p>g</p><p>A</p><p>fte</p><p>r c</p><p>ro</p><p>p</p><p>pl</p><p>an</p><p>tin</p><p>g</p><p>Permission to use this table from Bob Hartzler. Source: Iowa State Univ. Weed</p><p>Science. Reference details for the table on the last page of this publication:</p><p>store.extension.iastate.edu/Product/sa11-pdf.</p><p>http://store.extension.iastate.edu/Product/sa11-pdf</p><p>201</p><p>W</p><p>eed Identification</p><p>201</p><p>W</p><p>eed Identification</p><p>Using scouting information to plan weed management</p><p>strategies (now and future)</p><p>When done correctly, weed scouting is more than just simply observing</p><p>weeds. Consistent patterns and issues should be recognized and</p><p>resistant weeds and species shifts should be diagnosed. Information</p><p>gathered during this season will impact weed management decisions</p><p>next year. This information will be useful in planning effective strategies</p><p>for both the immediate and long-term needs.</p><p>202</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>202</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>GRASS AND GRASSLIKE WEED</p><p>VEGETATIVE KEY</p><p>Reprinted with permission from Broadleaf and Grass, and Grasslike Weed</p><p>Vegetative Identification Keys (pubsplus.illinois.edu/product/broadleaf-and-</p><p>grass-and-grasslike-weed-vegetative-identification-keys).</p><p>Li</p><p>gu</p><p>le</p><p>A</p><p>bs</p><p>en</p><p>t</p><p>St</p><p>em</p><p>s</p><p>ro</p><p>u</p><p>nd</p><p>to</p><p>fl</p><p>at</p><p>te</p><p>ne</p><p>d</p><p>T</p><p>ri</p><p>an</p><p>gu</p><p>la</p><p>r</p><p>st</p><p>em</p><p>s</p><p>C</p><p>u</p><p>lm</p><p>s</p><p>(s</p><p>te</p><p>m</p><p>s)</p><p>ro</p><p>u</p><p>nd</p><p>, 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D</p><p>ia</p><p>ne</p><p>A</p><p>nd</p><p>er</p><p>so</p><p>n,</p><p>a</p><p>nd</p><p>o</p><p>th</p><p>er</p><p>W</p><p>ee</p><p>d</p><p>S</p><p>ci</p><p>en</p><p>ce</p><p>E</p><p>xt</p><p>en</p><p>si</p><p>on</p><p>S</p><p>p</p><p>ec</p><p>ia</p><p>lis</p><p>ts</p><p>, U</p><p>ni</p><p>ve</p><p>rs</p><p>it</p><p>y</p><p>of</p><p>Il</p><p>lin</p><p>oi</p><p>s</p><p>E</p><p>xt</p><p>en</p><p>si</p><p>on</p><p>, U</p><p>ni</p><p>ve</p><p>rs</p><p>it</p><p>y</p><p>of</p><p>Il</p><p>lin</p><p>oi</p><p>s</p><p>at</p><p>U</p><p>rb</p><p>an</p><p>a-</p><p>C</p><p>ha</p><p>m</p><p>p</p><p>ai</p><p>gn</p><p>.</p><p>A</p><p>va</p><p>ila</p><p>bl</p><p>e</p><p>fr</p><p>om</p><p>IT</p><p>C</p><p>S</p><p>In</p><p>st</p><p>ru</p><p>ct</p><p>io</p><p>na</p><p>l M</p><p>at</p><p>er</p><p>ia</p><p>ls</p><p>, I</p><p>nf</p><p>or</p><p>m</p><p>at</p><p>io</p><p>n</p><p>T</p><p>ec</p><p>hn</p><p>ol</p><p>og</p><p>y</p><p>an</p><p>d</p><p>C</p><p>om</p><p>m</p><p>u</p><p>ni</p><p>ca</p><p>ti</p><p>on</p><p>S</p><p>er</p><p>vi</p><p>ce</p><p>s,</p><p>C</p><p>ol</p><p>le</p><p>ge</p><p>o</p><p>f A</p><p>gr</p><p>ic</p><p>u</p><p>lt</p><p>u</p><p>ra</p><p>l,</p><p>C</p><p>on</p><p>su</p><p>m</p><p>er</p><p>a</p><p>nd</p><p>E</p><p>nv</p><p>ir</p><p>on</p><p>m</p><p>en</p><p>ta</p><p>l S</p><p>ci</p><p>en</p><p>ce</p><p>s,</p><p>19</p><p>17</p><p>S</p><p>. W</p><p>ri</p><p>gh</p><p>t S</p><p>t.,</p><p>C</p><p>ha</p><p>m</p><p>p</p><p>ai</p><p>gn</p><p>, I</p><p>lli</p><p>no</p><p>is</p><p>6</p><p>18</p><p>20</p><p>(</p><p>80</p><p>0)</p><p>3</p><p>45</p><p>-6</p><p>08</p><p>7</p><p>or</p><p>F</p><p>A</p><p>X</p><p>(2</p><p>17</p><p>) 3</p><p>33</p><p>-3</p><p>91</p><p>7.</p><p>C</p><p>op</p><p>yr</p><p>ig</p><p>ht</p><p>©</p><p>1</p><p>99</p><p>7,</p><p>1</p><p>99</p><p>9</p><p>by</p><p>th</p><p>e</p><p>B</p><p>oa</p><p>rd</p><p>o</p><p>f T</p><p>ru</p><p>st</p><p>ee</p><p>s</p><p>of</p><p>th</p><p>e</p><p>U</p><p>ni</p><p>ve</p><p>rs</p><p>it</p><p>y</p><p>of</p><p>Il</p><p>lin</p><p>oi</p><p>s.</p><p>{</p><p>Li</p><p>gu</p><p>le</p><p>M</p><p>em</p><p>br</p><p>an</p><p>ou</p><p>s</p><p>204</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>204</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>ANNUAL GRASS WEEDS</p><p>FALL PANICUM</p><p>(Panicum dichotomiflorum)</p><p>Sheath: slightly flattened, smooth to occasionally</p><p>hairy</p><p>Blade: smooth, dull above and glossy below,</p><p>underside may have hair</p><p>Ligule: fringe of hairs</p><p>Auricles: absent</p><p>SMOOTH CRABGRASS</p><p>(Digitaria ischaemum)</p><p>Sheath: flattened and smooth, smooth margin</p><p>Blade: long hairs near ligule, rough margin</p><p>Ligule: long, membranous, rounded</p><p>Auricles: absent</p><p>LARGE CRABGRASS</p><p>(Digitaria sanguinalis)</p><p>Sheath: flattened with long scattered hairs</p><p>Blade: sparse hairs above and below</p><p>Ligule: membranous with notched margins</p><p>Auricles: absent</p><p>205</p><p>W</p><p>eed Identification</p><p>205</p><p>W</p><p>eed Identification</p><p>ANNUAL GRASS WEEDS (CONT.)</p><p>BARNYARDGRASS</p><p>(Echinochloa crus-galli)</p><p>Sheath: smooth and flattened</p><p>Blade: rough margin, prominent mid-vein</p><p>Ligule: absent</p><p>Auricles: absent</p><p>WITCHGRASS</p><p>(Panicum capillare)</p><p>Sheath: slightly flat, densely hairy</p><p>Ligule: short fringe of hairs</p><p>Blade: densely hairy above and below</p><p>Auricles: absent</p><p>SHATTERCANE</p><p>(Sorghum bicolor)</p><p>Sheath: rounded and smooth</p><p>Ligule: long, membranous, rounded; may be jagged</p><p>or ciliated</p><p>Blade: smooth but occasionally sparse hairs above</p><p>Auricles: absent</p><p>206</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>206</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>ANNUAL GRASS WEEDS (CONT.)</p><p>GIANT FOXTAIL</p><p>(Setaria faberi)</p><p>Sheath: round, hair on margin</p><p>Blade: short hairs covering upper surface</p><p>Ligule: fringe of hairs</p><p>Auricles: absent</p><p>YELLOW FOXTAIL</p><p>(Setaria glauca)</p><p>Sheath: flat, smooth margins</p><p>Blade: few long hairs near base</p><p>Ligule: fringe of hairs</p><p>Auricles: absent</p><p>GREEN FOXTAIL</p><p>(Setaria viridis)</p><p>Sheath: round, hair on margins</p><p>Blade: hairless</p><p>Ligule: fringe of hairs</p><p>Auricles: absent</p><p>207</p><p>W</p><p>eed Identification</p><p>207</p><p>W</p><p>eed Identification</p><p>PERENNIAL GRASS WEEDS</p><p>WIRESTEM MUHLY</p><p>(Muhlenbergia frondosa)</p><p>Sheath: flattened, smooth</p><p>Ligule: short, membranous, toothed margins</p><p>Blade: rough above, below, and on margins</p><p>Auricles: absent</p><p>QUACKGRASS</p><p>(Elytrigia repens)</p><p>Sheath: rounded, smooth to sparsely hairy</p><p>Blade: rough above, below, and on margins</p><p>Ligule: short, membranous</p><p>Auricles: long, slender, clasping</p><p>JOHNSONGRASS</p><p>(Sorghum halepense)</p><p>Sheath: rounded to flattened, smooth</p><p>Blade: smooth to sparsely hairy above and smooth</p><p>below</p><p>Ligule: long, rounded, possibly ciliated</p><p>208</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>208</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>BROADLEAF WEED VEGETATIVE KEY</p><p>Reprinted with permission from Broadleaf and Grass, and Grasslike Weed</p><p>Vegetative Identification Keys (pubsplus.illinois.edu/product/broadleaf-and-</p><p>grass-and-grasslike-weed-vegetative-identification-keys).</p><p>True leaf</p><p>margins not</p><p>parallel; leaf</p><p>tip pointed</p><p>Cotyledons</p><p>oval to round</p><p>Cotyledons</p><p>butterfly</p><p>shaped</p><p>OPTION A.</p><p>FIRST TRUE LEAVES</p><p>OPTION B.</p><p>FIRST TRUE LEAVES</p><p>Arrowhead</p><p>shaped</p><p>Star shaped Pentagon</p><p>shaped</p><p>Spade</p><p>shaped</p><p>Lobed</p><p>Venice</p><p>Mallow</p><p>Ivyleaf</p><p>Morningglory</p><p>Wild</p><p>Buckwheat</p><p>Pitted</p><p>Morningglory</p><p>Tall</p><p>Morningglory</p><p>Velvetleaf BurcucumberWild</p><p>Cucumber</p><p>Hedge Bindweed</p><p>(seedling)</p><p>Field Bindweed</p><p>(seedling)</p><p>If not, go to Option B</p><p>to heartshaped</p><p>True leaves dense-</p><p>ly hairy; margins</p><p>toothed</p><p>True leaves hairless to</p><p>sparsely hairy; margins</p><p>entire</p><p>Heart shapedShape:</p><p>True leaves lobed</p><p>(note exceptions)</p><p>True leaves spade, arrowhead, star,</p><p>or pentagon shaped</p><p>True leaves</p><p>without ochrea</p><p>True leaves</p><p>with ochrea</p><p>True leaves star or pentagon</p><p>shaped; cotyledons large and</p><p>spoon shaped</p><p>Ochrea</p><p>Arrangement: ALTERNATE</p><p>Leaves alternateLeaves alternate</p><p>True leaves spade or</p><p>arrowhead shaped;</p><p>cotyledons, if</p><p>present, kidney shaped</p><p>If not, go to Option C</p><p>Shape:</p><p>Arrangement: ALTERNATE</p><p>True leaf margins</p><p>sometimes purple</p><p>Cotyledon</p><p>“wings” broad</p><p>Cotyledon</p><p>“wings” long and</p><p>narrow</p><p>1st true leaf not</p><p>lobed; 3rd and</p><p>subsequent leaves</p><p>deeply lobed;</p><p>cotyledons ovate</p><p>All leaves lobed</p><p>(1st leaf may</p><p>be only slightly</p><p>lobed); cotyledons</p><p>butterfly shaped</p><p>with broad</p><p>“wings”</p><p>Cotyledons lan-</p><p>ceolate to elliptic</p><p>True leaves</p><p>star shaped</p><p>True leaves</p><p>pentagon</p><p>shaped</p><p>Using this key. This key describes common broadleaf</p><p>weed seedlings found in corn and soybeans in Illinois. It</p><p>focuses primarily on characteristics of the true leaves, but</p><p>in some cases the cotyledons are important (see figure</p><p>below). Options A, B, and C describe weeds that have</p><p>an alternate leaf arrangement. Option D contains weeds</p><p>with an opposite leaf arrangement. The leaves of most</p><p>weeds are either all alternate or all opposite. However,</p><p>in some weeds, the early true leaves are opposite but</p><p>later leaves are alternate. Note these exceptions given</p><p>in the key. (Cotyledons are always opposite.) Once leaf</p><p>arrangement has been determined, other characteristics</p><p>of the leaves and cotyledons are needed to follow the key.</p><p>It's very common when using a key to try more than one</p><p>route before reaching the correct species. The sketches of</p><p>many of the weeds are approximately life size. Others are</p><p>roughly one-half as large as actual size and are indicated</p><p>by 1/2X beside the sketch.</p><p>Broadleaf Weed</p><p>Vegetative Key</p><p>Prepared by C. Diane Anderson, William S. Curran, and</p><p>other extension specialists in weed science, University</p><p>of Illinois Extension, University of Illinois at Urbana-</p><p>Champaign.</p><p>Available from ITCS Instructional Materials, Information</p><p>Technology and Communication Services, College of</p><p>Agricultural, Consumer and Environmental Sciences,</p><p>1917 S. Wright St., Champaign, Illinois 61820</p><p>(800) 345-6087 or FAX (217) 333-3917.</p><p>Copyright © 1997, 1999 by the Board of Trustees of the</p><p>University of Illinois.</p><p>Ochrea of plants in the family</p><p>Polygonaceae (Buckwheat or</p><p>Smartweed family)</p><p>Plant Parts and Leaf Arrangement</p><p>of Broadleaf Weeds</p><p>{</p><p>{Ochrea</p><p>➤</p><p>➤</p><p>1/2X 1/2X</p><p>1/2X</p><p>1/2X</p><p>1/2X 1/2X</p><p>petiole</p><p>leaves (alternate)</p><p>leaves (opposite)</p><p>hypocotyl</p><p>cotyledons (opposite)</p><p>Z8</p><p>40</p><p>.1</p><p>True leaf</p><p>margins</p><p>parallel; leaf tip</p><p>blunt</p><p>209</p><p>W</p><p>eed Identification</p><p>209</p><p>W</p><p>eed Identification</p><p>BROADLEAF WEED</p><p>VEGETATIVE KEY (CONT.)</p><p>True leaf</p><p>margins not</p><p>parallel; leaf</p><p>tip pointed</p><p>Cotyledons</p><p>oval to round</p><p>Cotyledons</p><p>butterfly shaped</p><p>OPTION A.</p><p>FIRST TRUE LEAVES</p><p>OPTION B.</p><p>FIRST TRUE LEAVES</p><p>Arrowhead</p><p>shaped</p><p>Star shaped Pentagon</p><p>shaped</p><p>Spade</p><p>shaped</p><p>Lobed</p><p>Venice</p><p>Mallow</p><p>Ivyleaf</p><p>Morningglory</p><p>Wild</p><p>Buckwheat</p><p>Pitted</p><p>Morningglory</p><p>Tall</p><p>Morningglory</p><p>Velvetleaf BurcucumberWild</p><p>Cucumber</p><p>Hedge Bindweed</p><p>(seedling)</p><p>Field Bindweed</p><p>(seedling)</p><p>If not, go to Option B</p><p>to heartshaped</p><p>True leaves dense-</p><p>ly hairy; margins</p><p>toothed</p><p>True leaves hairless to</p><p>sparsely hairy; margins</p><p>entire</p><p>Heart shapedShape:</p><p>True leaves lobed</p><p>(note exceptions)</p><p>True leaves spade, arrowhead, star,</p><p>or pentagon shaped</p><p>True leaves</p><p>without ochrea</p><p>True leaves</p><p>with ochrea</p><p>True leaves star or pentagon</p><p>shaped; cotyledons large and</p><p>spoon shaped</p><p>Ochrea</p><p>Arrangement: ALTERNATE</p><p>Leaves alternateLeaves alternate</p><p>True leaves spade or</p><p>arrowhead shaped;</p><p>cotyledons, if</p><p>present, kidney shaped</p><p>If not, go to Option C</p><p>Shape:</p><p>Arrangement: ALTERNATE</p><p>True leaf margins</p><p>sometimes purple</p><p>Cotyledon</p><p>“wings” broad</p><p>Cotyledon</p><p>“wings” long and</p><p>narrow</p><p>1st true leaf not</p><p>lobed; 3rd and</p><p>subsequent leaves</p><p>deeply lobed;</p><p>cotyledons ovate</p><p>All leaves lobed</p><p>(1st leaf may</p><p>be only slightly</p><p>lobed); cotyledons</p><p>butterfly shaped</p><p>with broad</p><p>“wings”</p><p>Cotyledons lan-</p><p>ceolate to elliptic</p><p>True leaves</p><p>star shaped</p><p>True leaves</p><p>pentagon</p><p>shaped</p><p>Using this key. This key describes common broadleaf</p><p>weed seedlings found in corn and soybeans in Illinois. It</p><p>focuses primarily on characteristics of the true leaves, but</p><p>in some cases the cotyledons are important (see figure</p><p>below). Options A, B, and C describe weeds that have</p><p>an alternate leaf arrangement. Option D contains weeds</p><p>with an opposite leaf arrangement. The leaves of most</p><p>weeds are either all alternate or all opposite. However,</p><p>in some weeds, the early true leaves are opposite but</p><p>later leaves are alternate. Note these exceptions given</p><p>in the key. (Cotyledons are always opposite.) Once leaf</p><p>arrangement has been determined, other characteristics</p><p>of the leaves and cotyledons are needed to follow the key.</p><p>It's very common when using a key to try more than one</p><p>route before reaching the correct species. The sketches of</p><p>many of the weeds are approximately life size. Others are</p><p>roughly one-half as large as actual size and are indicated</p><p>by 1/2X beside the sketch.</p><p>Broadleaf Weed</p><p>Vegetative Key</p><p>Prepared by C. Diane Anderson, William S. Curran, and</p><p>other extension specialists in weed science, University</p><p>of Illinois Extension, University of Illinois at Urbana-</p><p>Champaign.</p><p>Available from ITCS Instructional Materials, Information</p><p>Technology and Communication Services, College of</p><p>Agricultural, Consumer and Environmental Sciences,</p><p>1917 S. Wright St., Champaign, Illinois 61820</p><p>(800) 345-6087 or FAX (217) 333-3917.</p><p>Copyright © 1997, 1999 by the Board of Trustees of the</p><p>University of Illinois.</p><p>Ochrea of plants in the family</p><p>Polygonaceae (Buckwheat or</p><p>Smartweed family)</p><p>Plant Parts and Leaf Arrangement</p><p>of Broadleaf Weeds</p><p>{</p><p>{Ochrea</p><p>➤</p><p>➤</p><p>1/2X 1/2X</p><p>1/2X</p><p>1/2X</p><p>1/2X 1/2X</p><p>petiole</p><p>leaves (alternate)</p><p>leaves (opposite)</p><p>hypocotyl</p><p>cotyledons (opposite)</p><p>Z8</p><p>40</p><p>.1</p><p>True leaf</p><p>margins</p><p>parallel; leaf tip</p><p>blunt</p><p>210</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>210</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>BROADLEAF WEED</p><p>VEGETATIVE KEY (CONT.)</p><p>Reprinted with permission from Broadleaf and Grass, and Grasslike Weed</p><p>Vegetative Identification Keys (https://pubsplus.illinois.edu/product/broadleaf-</p><p>and-grass-and-grasslike-weed-vegetative-identification-keys).</p><p>Oval</p><p>Spoon</p><p>shapedEllipticOvate Lanceolate Oblong</p><p>Plants with</p><p>ochrea; no</p><p>odor</p><p>Cotyledon</p><p>midrib</p><p>prominent</p><p>Leaf underside</p><p>often purplish</p><p>Leaves may be</p><p>sparsely hairy</p><p>Kochia Jimsonweed</p><p>Common</p><p>Lambsquarters</p><p>Pennsylvania</p><p>SmartweedWild Mustard</p><p>Smooth Pigweed or</p><p>Redroot Pigweed</p><p>Tall Waterhemp</p><p>Leaf underside</p><p>often reddish</p><p>Eastern Black</p><p>Nightshade</p><p>Prickly Sida</p><p>OPTION D.</p><p>FIRST TRUE LEAVES</p><p>Venice Mallow</p><p>Giant Ragweed</p><p>Common Ragweed</p><p>Common Sunflower</p><p>Honeyvine Milkweed</p><p>(seedling)</p><p>Common Cocklebur</p><p>Common Milkweed</p><p>(seedling)</p><p>Hemp Dogbane</p><p>(seedling)</p><p>OPTION C.</p><p>FIRST TRUE LEAVES</p><p>Arrangement: ALTERNATE</p><p>Leaves alternate</p><p>Shape: If not, go to Option D</p><p>Ochrea</p><p>True leaves</p><p>densely hairy</p><p>True leaves hairless</p><p>(or sparsely hairy)</p><p>1st true leaves</p><p>lanceolate to</p><p>elliptic</p><p>True leaves</p><p>ovate to oval</p><p>True leaves</p><p>covered with</p><p>mealy white</p><p>“granules” or</p><p>“frost”</p><p>True leaves</p><p>without white</p><p>“granules” or</p><p>“frost”</p><p>Plants with</p><p>distinctive odor</p><p>when crushed</p><p>True leaves</p><p>spoon</p><p>shaped;</p><p>cotyledons</p><p>kidney</p><p>shaped</p><p>True leaves</p><p>and cotyledons</p><p>oblong</p><p>about 48 hours in a flooded</p><p>soil. Without oxygen, the plant cannot perform critical life-sustaining</p><p>functions; e.g., nutrient and water uptake is impaired, root growth is</p><p>inhibited, etc. If temperatures are warm during flooding (greater than 77</p><p>degrees Fahrenheit) plants may not survive 24 hours. Cooler temperatures</p><p>prolong survival.</p><p>To confirm plant survival, check the color of the growing point. It should</p><p>be white to cream colored, while a darkening and/or softening usually</p><p>precedes plant death. Also look for new leaf growth three to five days</p><p>after water drains from the field. Sometimes the growing point is killed by</p><p>bacterial infections during and after flooding, but plant growth continues</p><p>in the form of non-productive tillers (suckers).</p><p>12</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>12</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>ESTIMATED PERCENTAGE</p><p>CORN GRAIN YIELD LOSS DUE</p><p>TO DEFOLIATION AT VARIOUS</p><p>GROWTH STAGES1</p><p>Growth</p><p>Stage2</p><p>% Leaf Defoliation</p><p>10 20 30 40 50 60 70 80 90 100</p><p>% Yield Loss</p><p>7 leaf 0 0 0 1 2 4 5 6 8 9</p><p>9 leaf 0 0 1 2 4 6 7 9 11 13</p><p>11 leaf 0 1 2 5 7 9 11 14 18 22</p><p>13 leaf 0 1 3 6 10 13 17 22 28 34</p><p>15 leaf 1 2 5 9 15 20 26 34 42 51</p><p>17 leaf 2 4 7 13 21 28 37 48 59 72</p><p>19–21 leaf 3 6 11 18 27 38 51 64 79 96</p><p>Tassel 3 7 13 21 31 42 55 68 83 100</p><p>Silked 3 7 12 20 29 39 51 65 80 97</p><p>Silks Brown 2 6 11 18 27 36 47 60 74 90</p><p>Blister 2 5 10 16 22 30 39 50 60 73</p><p>Milk 1 3 7 12 18 24 32 41 49 59</p><p>Soft Dough 1 2 4 8 12 17 23 29 35 41</p><p>Early Dent 0 1 2 5 9 13 18 23 27 32</p><p>Late Dent 0 0 1 3 5 7 9 11 13 15</p><p>Mature 0 0 0 0 0 0 0 0 0 0</p><p>1 Adapted from the National Crop Insurance Service’s “Corn Loss Instruction”</p><p>(Rev. 1984)</p><p>2 As determined by counting fully expanded leaves (i.e., those with 40–50</p><p>percent of leaf exposed from whorl and whose tip points below the horizontal.)</p><p>13</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>13</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>EFFECTS OF PLANT DAMAGE</p><p>DURING GRAIN FILL IN CORN</p><p>Early killing frost in the fall may damage immature corn and cause yield</p><p>reductions. The effect of frost damage to corn depends on the severity</p><p>of defoliation, stalk damage, and stage of growth. The following tables</p><p>provide yield loss and moisture estimates associated with premature plant</p><p>death during grain fill.</p><p>Yield Loss in Corn Due to Premature Plant Death</p><p>Time of Death</p><p>Yield Loss from Death of:</p><p>Leaves only Whole plant</p><p>(% of normal)</p><p>Soft dough 35 55</p><p>Full dent 27 41</p><p>Milk line halfway down kernel 6 12</p><p>Effect of Premature Plant Death on Whole Plant and</p><p>Grain Moisture</p><p>Time of death</p><p>Percent Moisture of:</p><p>Grain Whole plant</p><p>(% of normal)</p><p>Soft dough 65 >75</p><p>Full dent 55 75</p><p>Milk line halfway down kernel 40 69</p><p>Normal black layer development 33 61</p><p>Reference publications: NCH-18, NCH-57.</p><p>14</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>14</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>ESTIMATING CORN YIELDS PRIOR</p><p>TO HARVEST</p><p>There are several techniques for estimating corn grain yield prior to</p><p>harvest. This version was developed by the Agricultural Engineering</p><p>Department at the University of Illinois and is the one most commonly</p><p>used. A numerical constant for kernel weight is figured into the equation in</p><p>order to calculate grain yield. Since weight per kernel will vary depending</p><p>on hybrid and environment, the yield equation should only be used to</p><p>estimate relative grain yield. For example, yield will be overestimated in</p><p>a year with poor grain fill conditions, while it will be underestimated in a</p><p>year with good grain fill conditions.</p><p>Step 1.</p><p>Count the number of harvestable ears per 1/1000th acre</p><p>(see page 268).</p><p>Step 2.</p><p>Count the number of kernel rows per ear on every fifth ear.</p><p>Calculate the average.</p><p>Step 3.</p><p>Count the number of kernels per row on each of the same</p><p>ears, but do not count kernels on either the butt or tip that</p><p>are less than half size. Calculate the average.</p><p>Step 4.</p><p>Yield (bushels per acre) equals:</p><p>(ear #) x (avg. row #) x (kernel #)</p><p>90</p><p>ESTIMATING CORN SILAGE YIELDS</p><p>Silage yields for a given grain yield can vary a bit depending on how well</p><p>eared and developed the crop is. Generally, in well-eared corn, you can</p><p>estimate silage yields by dividing grain yields by about 7.0 bushels per</p><p>ton. A crop 140 bushel grain yield potential would have a silage yield</p><p>potential of about 20 tons per acre. This is only an estimate because the</p><p>number of bushels per ton can vary depending on the condition of the</p><p>crop. In drought stunted crops without ears, wet silage (35 percent DM)</p><p>yields are about 1 ton per foot of height, so a 5-foot tall crop would yield</p><p>about 5 tons per acre.</p><p>15</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>15</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>SEED SPACING FOR PLANT</p><p>POPULATIONS</p><p>Planting</p><p>Rate/A</p><p>Final</p><p>Stand/A</p><p>(10%</p><p>loss)</p><p>Row Spacing (inches)</p><p>15 20 22 28 30 36 38 40</p><p>Inches Between Kernels</p><p>15,000 13,500 27.9 20.9 17.6 14.9 13.9 11.6 11.0 10.5</p><p>16,000 14,400 26.1 19.6 16.5 14.0 13.1 10.9 10.3 9.8</p><p>17,000 15,300 24.6 18.4 15.5 13.2 12.3 10.2 9.7 9.2</p><p>18,000 16,200 23.2 17.4 14.7 12.4 11.6 9.7 9.2 8.7</p><p>19,000 17,100 22.0 16.5 13.9 11.8 11.0 9.2 8.7 8.2</p><p>20,000 18,000 20.9 15.7 13.2 11.2 10.5 8.7 8.3 7.8</p><p>22,000 19,800 19.0 14.3 12.0 10.2 9.5 7.9 7.5 7.1</p><p>24,000 21,600 17.4 13.1 11.0 9.3 8.7 7.2 6.9 6.5</p><p>26,000 23,400 16.1 12.1 10.1 8.6 8.1 6.7 6.4 6.0</p><p>28,000 25,200 14.9 11.2 9.4 8.0 7.5 6.2 5.9 5.6</p><p>30,000 27,000 13.9 10.4 8.8 7.5 7.0 5.8 5.5 5.2</p><p>32,000 28,800 13.1 9.8 8.5 7.0 6.6 5.4 5.2 4.9</p><p>34,000 30,600 12.3 9.2 7.8 6.6 6.1 5.1 4.8 4.6</p><p>36,000 32,400 11.6 8.7 7.3 6.2 5.8 4.8 4.6 4.4</p><p>40,000 36,000 10.4 7.9 7.1 5.6 5.2 4.4 4.1 3.9</p><p>16</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>16</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>GROWING DEGREE DAY</p><p>ACCUMULATION NORMALS FROM</p><p>APRIL 1—OHIO</p><p>WEEK DATES NW NE SW SE</p><p>Apr 01–Apr 07 22 27 37 38</p><p>Apr 08–Apr 14 51 56 78 79</p><p>Apr 15–Apr 21 99 107 139 140</p><p>Apr 22–Apr 28 150 160 204 205</p><p>Apr 29–May 05 207 219 273 274</p><p>May 06–May 12 278 289 352 356</p><p>May 13–May 19 361 372 448 448</p><p>May 20–May 26 454 462 554 548</p><p>May 27–Jun 02 557 563 664 654</p><p>Jun 03–Jun 09 677 677 794 776</p><p>Jun 10–Jun 16 806 798 929 905</p><p>Jun 17–Jun 23 938 922 1067 1036</p><p>Jun 24–Jun 30 1080 1052 1214 1174</p><p>Jul 01–Jul 07 1223 1185 1364 1315</p><p>Jul 08–Jul 14 1376 1328 1522 1462</p><p>Jul 15–Jul 21 1534 1477 1682 1613</p><p>Jul 22–Jul 28 1689 1625 1846 1766</p><p>Jul 29–Aug 04 1834 1765 1999 1911</p><p>Aug 05–Aug 11 1979 1906 2152 2055</p><p>Aug 12–Aug 18 2115 039 2297 2194</p><p>Aug 19–Aug 25 2248 2168 2443 2333</p><p>Aug 26–Sep 01 2383 2299 2585 2473</p><p>Sep 02–Sep 08 2509 2420 2722 2600</p><p>Sep 09–Sep 15 2621 2531 2846 2717</p><p>Sep 16–Sep 22 2717 2624 2955 2820</p><p>Sep 23–Sep 29 2797 2703 3046 2909</p><p>Sep 30–Oct 06 2867 2771 3127 2984</p><p>Oct 07–Oct 13 2921 2827 3195 3047</p><p>Oct 14–Oct 20 2971 2879 3258 3107</p><p>Oct 21–Oct 27 3005 2917 3304 3151</p><p>Oct 28–Nov 03 3040 2955 3351 3198</p><p>Nov 04–Nov 10 3058 2976 3378 3226</p><p>Nov 11–Nov 17 3071 2992 3401 3246</p><p>Nov 18–Nov 24 3080 3002 3415 3262</p><p>Nov 25–Dec 01 3087 3012 3427 3274</p><p>Source: Midwestern Climate Center at Illinois State Water Survey.</p><p>GDDs calculated with 86/50 cutoff, base 50 method.</p><p>17</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>17</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>USING THE KERNEL MILKLINE AS A</p><p>GUIDE IN SILAGE HARVEST</p><p>Observing the development of the corn kernel milkline can provide a</p><p>guide as to when corn is at the proper dry matter content for ensiling.</p><p>Ohio research indicates variability in the relationship between the kernel</p><p>milkline and whole plant DM content. Hybrid, planting date, and growing</p><p>season can affect the relationship between kernel milkline position and</p><p>whole plant DM content. The appearance of the milkline in the upper 1/4</p><p>of the kernel generally indicates that the crop is very near the optimal</p><p>time to harvest. A sample should be taken at this time and DM content</p><p>determined with a commercial forage moisture tester or microwave oven.</p><p>When an ear of corn is broken in half, the tip half (shown below) shows</p><p>the smooth endosperm. The arrows point to the milk line border between</p><p>the milk and starch layer.</p><p>¾ milkline ½ milkline no milkline</p><p>18</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>18</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>ABNORMAL CORN EARS</p><p>“ARRESTED EARS”</p><p>Symptoms: Arrested ears exhibit</p><p>varying degrees of stunting</p><p>and tiny;</p><p>cotyledons</p><p>hairless</p><p>Arrangement: OPPOSITE</p><p>Leaves opposite</p><p>True leaf</p><p>margins entire</p><p>or lobed;</p><p>cotyledons</p><p>without</p><p>notched tip</p><p>True leaf mar-</p><p>gins toothed;</p><p>cotyledons</p><p>with notched</p><p>tip</p><p>True leaves</p><p>without</p><p>notched tip</p><p>True leaves with</p><p>notched tip</p><p>True leaves</p><p>oval to</p><p>ovate</p><p>True</p><p>leaves</p><p>ovate to</p><p>oblong</p><p>1st true leaves</p><p>without pointed</p><p>tip; cotyledons</p><p>oval to round</p><p>to heartshaped</p><p>True leaves</p><p>densely hairy</p><p>Cotyledons,</p><p>if present,</p><p>oblong</p><p>Plant as</p><p>large as</p><p>a quarter</p><p>at 2-leaf</p><p>stage</p><p>Plant as</p><p>large as a</p><p>silver</p><p>dollar at</p><p>2-leaf stage</p><p>Cotyledons,</p><p>if present,</p><p>oblong</p><p>Leaves</p><p>alternate after</p><p>1st true leaves</p><p>Cotyledons</p><p>thick and</p><p>waxy</p><p>True leaves</p><p>lobed</p><p>True leaves</p><p>not lobed</p><p>True leaves arrow-</p><p>head shaped</p><p>True leaves ovate</p><p>to lanceolate</p><p>True leaves rough</p><p>textured</p><p>True leaves</p><p>smooth, waxy, may</p><p>be slightly hairy;</p><p>sap milky</p><p>Cotyledons, if</p><p>present, lanceolate</p><p>to elliptic</p><p>True leaves</p><p>with 3-5 major</p><p>lobes</p><p>True leaves</p><p>with greater</p><p>than 5 major</p><p>lobes (“lacy”</p><p>appearance)</p><p>Later</p><p>leaves</p><p>alternate</p><p>True leaves</p><p>hairless or</p><p>sparsely hairy</p><p>1st true leaves with</p><p>pointed tip;</p><p>cotyledons ovate</p><p>➤</p><p>1/2X 1/2X 1/2X</p><p>1/2X</p><p>{</p><p>(difficult to</p><p>distinguish)</p><p>https://pubsplus.illinois.edu/product/broadleaf-and-grass-and-grasslike-weed-vegetative-identificati</p><p>https://pubsplus.illinois.edu/product/broadleaf-and-grass-and-grasslike-weed-vegetative-identificati</p><p>211</p><p>W</p><p>eed Identification</p><p>211</p><p>W</p><p>eed Identification</p><p>BROADLEAF WEED</p><p>VEGETATIVE KEY (CONT.)</p><p>Oval</p><p>Spoon</p><p>shapedEllipticOvate Lanceolate Oblong</p><p>Plants with</p><p>ochrea; no</p><p>odor</p><p>Cotyledon</p><p>midrib</p><p>prominent</p><p>Leaf underside</p><p>often purplish</p><p>Leaves may be</p><p>sparsely hairy</p><p>Kochia Jimsonweed</p><p>Common</p><p>Lambsquarters</p><p>Pennsylvania</p><p>SmartweedWild Mustard</p><p>Smooth Pigweed or</p><p>Redroot Pigweed</p><p>Tall Waterhemp</p><p>Leaf underside</p><p>often reddish</p><p>Eastern Black</p><p>Nightshade</p><p>Prickly Sida</p><p>OPTION D.</p><p>FIRST TRUE LEAVES</p><p>Venice Mallow</p><p>Giant Ragweed</p><p>Common Ragweed</p><p>Common Sunflower</p><p>Honeyvine Milkweed</p><p>(seedling)</p><p>Common Cocklebur</p><p>Common Milkweed</p><p>(seedling)</p><p>Hemp Dogbane</p><p>(seedling)</p><p>OPTION C.</p><p>FIRST TRUE LEAVES</p><p>Arrangement: ALTERNATE</p><p>Leaves alternate</p><p>Shape: If not, go to Option D</p><p>Ochrea</p><p>True leaves</p><p>densely hairy</p><p>True leaves hairless</p><p>(or sparsely hairy)</p><p>1st true leaves</p><p>lanceolate to</p><p>elliptic</p><p>True leaves</p><p>ovate to oval</p><p>True leaves</p><p>covered with</p><p>mealy white</p><p>“granules” or</p><p>“frost”</p><p>True leaves</p><p>without white</p><p>“granules” or</p><p>“frost”</p><p>Plants with</p><p>distinctive odor</p><p>when crushed</p><p>True leaves</p><p>spoon</p><p>shaped;</p><p>cotyledons</p><p>kidney</p><p>shaped</p><p>True leaves</p><p>and cotyledons</p><p>oblong and tiny;</p><p>cotyledons</p><p>hairless</p><p>Arrangement: OPPOSITE</p><p>Leaves opposite</p><p>True leaf</p><p>margins entire</p><p>or lobed;</p><p>cotyledons</p><p>without</p><p>notched tip</p><p>True leaf mar-</p><p>gins toothed;</p><p>cotyledons</p><p>with notched</p><p>tip</p><p>True leaves</p><p>without</p><p>notched tip</p><p>True leaves with</p><p>notched tip</p><p>True leaves</p><p>oval to</p><p>ovate</p><p>True</p><p>leaves</p><p>ovate to</p><p>oblong</p><p>1st true leaves</p><p>without pointed</p><p>tip; cotyledons</p><p>oval to round</p><p>to heartshaped</p><p>True leaves</p><p>densely hairy</p><p>Cotyledons,</p><p>if present,</p><p>oblong</p><p>Plant as</p><p>large as</p><p>a quarter</p><p>at 2-leaf</p><p>stage</p><p>Plant as</p><p>large as a</p><p>silver</p><p>dollar at</p><p>2-leaf stage</p><p>Cotyledons,</p><p>if present,</p><p>oblong</p><p>Leaves</p><p>alternate after</p><p>1st true leaves</p><p>Cotyledons</p><p>thick and</p><p>waxy</p><p>True leaves</p><p>lobed</p><p>True leaves</p><p>not lobed</p><p>True leaves arrow-</p><p>head shaped</p><p>True leaves ovate</p><p>to lanceolate</p><p>True leaves rough</p><p>textured</p><p>True leaves</p><p>smooth, waxy, may</p><p>be slightly hairy;</p><p>sap milky</p><p>Cotyledons, if</p><p>present, lanceolate</p><p>to elliptic</p><p>True leaves</p><p>with 3-5 major</p><p>lobes</p><p>True leaves</p><p>with greater</p><p>than 5 major</p><p>lobes (“lacy”</p><p>appearance)</p><p>Later</p><p>leaves</p><p>alternate</p><p>True leaves</p><p>hairless or</p><p>sparsely hairy</p><p>1st true leaves with</p><p>pointed tip;</p><p>cotyledons ovate</p><p>➤</p><p>1/2X 1/2X 1/2X</p><p>1/2X</p><p>{</p><p>(difficult to</p><p>distinguish)</p><p>212</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>212</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>SUMMER ANNUAL</p><p>BROADLEAF WEEDS</p><p>COMMON COCKLEBUR</p><p>(Xanthium strumarium)</p><p>Cotyledon: lanceolate, waxy and dark green</p><p>Leaf: rough, triangular, with slightly lobed margin; first leaves are</p><p>opposite, others are alternate</p><p>Stem: erect, ridged, rough, hairy, and purple-spotted</p><p>COMMON LAMBSQUARTERS</p><p>(Chenopodium album)</p><p>Cotyledon: small but linear</p><p>Leaf: white mealy coating both above and below, especially on</p><p>young leaves; first true leaves are opposite, others are</p><p>alternate with triangular shape and serrated</p><p>Stem: erect, smooth, grooved, strong and sometimes purple at</p><p>the nodes</p><p>213</p><p>W</p><p>eed Identification</p><p>213</p><p>W</p><p>eed Identification</p><p>SUMMER ANNUAL</p><p>BROADLEAF WEEDS (CONT.)</p><p>PRICKLY LETTUCE</p><p>(Lactuca serriola )</p><p>Cotyledon: spatulate with slight indentation at tip, hairy</p><p>Leaf: prickly spines along underside of midrib, first leaves are</p><p>spatulate, later becoming deeply lobed with weak spines,</p><p>hairy</p><p>Stem: hollow with a milky juice</p><p>JIMSONWEED</p><p>(Datura stramonium)</p><p>Cotyledon: smooth and lanceolate, whole seedling plant has a</p><p>pungent odor when crushed</p><p>Leaf: smooth, waxy, multipointed margins</p><p>Stem: hairy hypocotyl, smooth and tough</p><p>214</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>214</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>SUMMER ANNUAL BROADLEAF</p><p>WEEDS (CONT.)</p><p>IVYLEAF MORNINGGLORY</p><p>(Ipomoea hederacea)</p><p>Cotyledon: smooth, shiny, and butterfly-shaped</p><p>Leaf: alternate, tall and upright hairs, on both sides, 3-lobed</p><p>giving an ivy shape</p><p>Stem: thin, hairy, vine-like</p><p>TALL MORNINGGLORY</p><p>(Ipomoea purpurea)</p><p>Cotyledon: smooth, shiny and butterfly-shaped</p><p>Leaf: alternate, dense, short appressed hairs on both sides,</p><p>although less below, and broadly heart-shaped</p><p>Stem: thin, dense, very short hairs, vine-like</p><p>215</p><p>W</p><p>eed Identification</p><p>215</p><p>W</p><p>eed Identification</p><p>SUMMER ANNUAL BROADLEAF</p><p>WEEDS (CONT.)</p><p>WILD MUSTARD</p><p>(Brassica kaber)</p><p>Cotyledon: kidney-shaped and smooth</p><p>Leaf: alternate and hairy, lower leaves are lobed, have petioles</p><p>and vary in size and shape, upper leaves are smaller, have</p><p>no petioles and are not as lobed and irregular</p><p>Stem: hairy near base</p><p>Other: four yellow petals on flowers</p><p>EASTERN BLACK NIGHTSHADE</p><p>(Solanum ptycanthum)</p><p>Cotyledon: small, ovate, green both surfaces</p><p>Leaf: waxy appearance on top, purple below, some hair and</p><p>small lobes</p><p>Stem: erect, smooth, fleshy, weak</p><p>216</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>216</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>SUMMER ANNUAL BROADLEAF</p><p>WEEDS (CONT.)</p><p>REDROOT PIGWEED</p><p>(Amaranthus retroflexus)</p><p>Cotyledon: linear, hairless</p><p>Leaf: alternate, slightly notched/indented at tip</p><p>Stem: erect, short hairs, red to purplish color on stems and</p><p>petiole</p><p>PALMER AMARANTH</p><p>(Amaranthus palmeri)</p><p>Cotyledon: linear and hairless</p><p>Leaf: Alternate, no hair, ovate to diamond shape, petiole longer</p><p>than the leaf, plant can have a rosette-like appearance</p><p>when viewed from above, often a single short hair at the</p><p>leaf tip</p><p>Stem: erect, no hair, and varying color from green to red</p><p>217</p><p>W</p><p>eed Identification</p><p>217</p><p>W</p><p>eed Identification</p><p>SUMMER ANNUAL BROADLEAF</p><p>WEEDS (CONT.)</p><p>COMMON/TALL WATERHEMP</p><p>(Amaranthus rudis/tuberculatus)</p><p>Cotyledon: linear and hairless</p><p>Leaf: alternate, no hair, leaf is longer than it is wide making it</p><p>more linear than pigweeds, usually a wavy leaf margin, and</p><p>no notch at tip</p><p>Stem: erect, no hair, and varying color from green to red</p><p>218</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>218</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>SUMMER ANNUAL BROADLEAF</p><p>WEEDS (CONT.)</p><p>COMMON RAGWEED</p><p>(Ambrosia artemisifolia)</p><p>Cotyledon: oval to spatulate with grooved petioles, and purple</p><p>undersides</p><p>Leaf: lots of variation, lacy appearance, sometimes hairy below,</p><p>smooth above, opposite early but turning alternate</p><p>GIANT RAGWEED</p><p>(Ambrosia trifida)</p><p>Cotyledon: oval to spatulate with grooved petioles, similar to common</p><p>ragweed cotyledons but three to four times larger, with</p><p>green undersides instead of purple</p><p>Leaf: rough, hairy, deeply lobed—three to five lobes, sometimes</p><p>with no lobes, opposite early but turning alternate</p><p>Stem: erect, rough, hairy</p><p>219</p><p>W</p><p>eed Identification</p><p>219</p><p>W</p><p>eed Identification</p><p>SUMMER ANNUAL BROADLEAF</p><p>WEEDS (CONT.)</p><p>PENNSYLVANIA SMARTWEED</p><p>(Polygonum pennsylvanicum)</p><p>Cotyledon: lanceolate with rounded tips</p><p>Leaf: alternate, smooth edges, may or may not have purple</p><p>thumbprint</p><p>Stem: erect, smooth, ochrea at base of petiole, no hair on ochrea</p><p>VELVETLEAF</p><p>(Abutilon theophrasti)</p><p>Cotyledon: one round and one heart-shaped cotyledon, both hairy</p><p>Leaf: densely hairy (possessing a velvety texture), heart-shaped</p><p>Stem: erect, densely hairy</p><p>220</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>220</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>WINTER ANNUAL BROADLEAF</p><p>WEEDS</p><p>COMMON CHICKWEED</p><p>(Stellaria media)</p><p>Cotyledon: broadly ovate, pale green</p><p>Leaf: hairless, small, pale green, pointed at tip</p><p>Stem: erect, stems and petioles sparsely hairy, hypocotyl red</p><p>PURPLE DEADNETTLE</p><p>(Lamium purpureum)</p><p>Cotyledon: round to square, no</p><p>hair, petiole shorter</p><p>than henbit, a white</p><p>point at tip, cotyledon</p><p>lobes at petiole</p><p>usually touch each</p><p>other</p><p>Leaf: opposite, twice the</p><p>amount and length</p><p>of hair compared to</p><p>henbit, serrated leaf</p><p>margin, leaves always have petioles, round to triangular</p><p>shaped leaves</p><p>Stem: erect to prostrate, square, twice the amount and length of</p><p>hair compared to henbit</p><p>221</p><p>W</p><p>eed Identification</p><p>221</p><p>W</p><p>eed Identification</p><p>WINTER ANNUAL BROADLEAF</p><p>WEEDS (CONT.)</p><p>HENBIT</p><p>(Lamium amplexicaule)</p><p>Cotyledon: round to square, no</p><p>hair, petiole longer</p><p>and more vertical than</p><p>deadnettle, a white</p><p>point at tip, cotyledon</p><p>lobes at petiole</p><p>usually do not touch</p><p>each other creating a</p><p>square at the petiole</p><p>Leaf: opposite, half the</p><p>amount and length of hair compared to deadnettle,</p><p>serrated leaf margin, leaves have petioles as a seedling,</p><p>but do not have petioles when flowering begins, round-</p><p>shaped leaves</p><p>Stem: erect to prostrate, square, half the amount and length of</p><p>hair compared to deadnettle</p><p>MARESTAIL/HORSEWEED</p><p>(Conyza canadensis)</p><p>Cotyledon: smooth and green</p><p>Leaf: often hairy, numerous, linear, crowded together around</p><p>stem, later alternate</p><p>Stem: erect, bristly hairs, strong</p><p>222</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>222</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>WINTER ANNUAL BROADLEAF</p><p>WEEDS (CONT.)</p><p>FIELD PENNYCRESS</p><p>(Thlaspi arvense)</p><p>Cotyledon: round, hairless</p><p>Leaf: no hair, alternate,</p><p>margins of first</p><p>leaves are serrated to</p><p>smooth, later margins</p><p>are more lobed, stem</p><p>leaves clasp the stem,</p><p>when crushed an odor</p><p>is produced</p><p>Stem: hairless, basal rosette</p><p>is formed first followed by an erect stem</p><p>SHEPHERD’S-PURSE</p><p>(Capsella bursa-pastoris)</p><p>Cotyledon: oval to spatulate</p><p>Leaf: similar to cotyledons when young, changing to variable in</p><p>shape with lobed or toothed and undulating margins, hairy</p><p>Special: rosette in the vegetative stage, rosette with erect stem in</p><p>the reproductive stage</p><p>Other: seed pods resemble a purse</p><p>223</p><p>W</p><p>eed Identification</p><p>223</p><p>W</p><p>eed Identification</p><p>BIENNIAL BROADLEAF WEEDS</p><p>WILD CARROT</p><p>(Daucus carota)</p><p>Cotyledon: long, linear, smooth</p><p>Leaf: compound, lacy, hairy, smells like a carrot</p><p>Special: rosette the first year, second year grows a hairy stem, then</p><p>flowers and dies</p><p>Other: sometimes referred to as Queen Anne’s Lace</p><p>POISON HEMLOCK</p><p>(Conium maculatum)</p><p>Cotyledon: oblong to elliptical</p><p>shaped, hairless, veins</p><p>very prominent</p><p>Leaf: finely divided,</p><p>although each</p><p>division is wider</p><p>than wild carrot, no</p><p>hair, petioles may</p><p>have purple spots,</p><p>alternate, when</p><p>crushed a musty odor</p><p>is present</p><p>Stem: hairless, purple spots on erect stem, basal rosette formed</p><p>first followed by an erect stem</p><p>224</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>224</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>PERENNIAL BROADLEAF WEEDS</p><p>DANDELION</p><p>(Taraxacum officinale)</p><p>Plants can sprout from seed or below ground roots. Cotyledons</p><p>spatulate to oblong-shaped with no hair. Leaves are variously lobed,</p><p>and emerge in a rosette. Little or no hair on leaves. A yellow ray of</p><p>flowers appears on a long, fleshy, hollow stem.</p><p>CURLY DOCK</p><p>(Rumex crispus)</p><p>It is a simple perennial, so it can</p><p>emerge from seed or tap root.</p><p>As a seedling the cotyledons are</p><p>linear to oblong and hairless. All</p><p>nodes have a prominent ochrea.</p><p>Leaves are linear with a wavy leaf</p><p>margin, hairless, and alternate.</p><p>Stems are short early appearing</p><p>as a rosette and later produce</p><p>an erect stem. Stem leaves are</p><p>usually shorter than basal leaves.</p><p>Leaves and stems often have</p><p>reddish spots on them.</p><p>225</p><p>W</p><p>eed Identification</p><p>225</p><p>W</p><p>eed Identification</p><p>PERENNIAL BROADLEAF WEEDS</p><p>(CONT.)</p><p>HEMP DOGBANE</p><p>(Apocynum cannabinum)</p><p>Reproducing by seed or long horizontal rootstock. Leaves are oblong</p><p>to elliptical, opposite, and erect. Stems are woody and often red at the</p><p>base, branching, and exude a milky substance when broken. No hair on</p><p>leaves or stem.</p><p>COMMON MILKWEED</p><p>(Asclepias syriaca)</p><p>Similar to hemp dogbane, except the stem does not branch. The leaves</p><p>are larger and more elliptical than hemp dogbane and all plant parts</p><p>exude a milky substance when broken. Underside of leaves are hairy.</p><p>226</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>226</p><p>W</p><p>ee</p><p>d</p><p>Id</p><p>en</p><p>tifi</p><p>ca</p><p>tio</p><p>n</p><p>PERENNIAL BROADLEAF WEEDS</p><p>(CONT.)</p><p>COMMON POKEWEED</p><p>(Phytolacca americana)</p><p>Plants can develop from seed or a large poisonous taproot. Leaves</p><p>appear folded and crinkled when emerging from the soil but soon</p><p>develop into large simple leaves. Plants have a smooth red stem which</p><p>can reach a height of 9 feet. Sometimes called “inkberry” because of its</p><p>distinctive shiny dark-purple berries.</p><p>CANADA THISTLE</p><p>(Cirsium arvense)</p><p>Can emerge from seeds or creeping roots, beginning as a rosette but</p><p>quickly elongating a stem which branches only at the top. Leaves clasp</p><p>the stem, have crinkled margins, and lobes which end in spiny tips. The</p><p>stem has no spines, but does have hair. Flowers are purple.</p><p>227</p><p>P</p><p>esticide A</p><p>pplication Technology</p><p>227</p><p>P</p><p>esticide A</p><p>pplication Technology</p><p>PESTICIDE APPLICATION</p><p>TECHNOLOGY</p><p>Application of pesticides requires more skill and knowledge than any</p><p>other field operation you may be involved in when producing field crops</p><p>such as corn, soybean, wheat, and alfalfa. Although each crop may</p><p>require a slightly different approach to application of pesticides, there</p><p>are some general principles that apply to almost all spraying situations.</p><p>Following these principles will get you much closer to success in achieving</p><p>satisfactory and economic control of the problem, regardless of whatever</p><p>it is that you are trying to control.</p><p>These major principles are:</p><p>1. positive identification of the pest;</p><p>2. using the right pesticide designed to specifically control that pest;</p><p>3. selecting the right equipment, and particularly the right type and size</p><p>of nozzle for the job;</p><p>4. applying the pesticide at the right time; and</p><p>5. checking the accuracy of equipment (calibration) periodically to make</p><p>sure that you are applying the amount recommended on the label,</p><p>applying pesticides uniformly onto the target.</p><p>228</p><p>P</p><p>es</p><p>tic</p><p>id</p><p>e</p><p>A</p><p>pp</p><p>lic</p><p>at</p><p>io</p><p>n</p><p>Te</p><p>ch</p><p>no</p><p>lo</p><p>gy</p><p>228</p><p>P</p><p>es</p><p>tic</p><p>id</p><p>e</p><p>A</p><p>pp</p><p>lic</p><p>at</p><p>io</p><p>n</p><p>Te</p><p>ch</p><p>no</p><p>lo</p><p>gy</p><p>Certain tasks taking place during application of pesticides must be</p><p>accomplished to achieve maximum biological efficacy from pesticides</p><p>applied. These tasks include:</p><p>1. uniform mixing of pesticides (especially dry products) in the sprayer</p><p>tank which can only be accomplished if the agitation system in the tank</p><p>has sufficient capacity for a given tank size, and is operating properly;</p><p>2. choosing a pump that has sufficient capacity to deliver the required</p><p>gallonage (gal/acre) to the nozzles;</p><p>3. making sure hoses and fittings between the pump and the nozzles are</p><p>sized properly to reduce pressure losses to a minimum;</p><p>4. transporting the pesticides with minimum loss from the nozzles to the</p><p>target;</p><p>5. attaining maximum retention of droplets on the target (minimum</p><p>rebound); and</p><p>6. providing thorough and uniform coverage of target with droplets</p><p>carrying active ingredients.</p><p>In this</p><p>chapter, only the most critical issues related to application of</p><p>pesticides are discussed. For detailed coverage of these and other topics,</p><p>visit the websites of other resources given throughout the chapter.</p><p>229</p><p>P</p><p>esticide A</p><p>pplication Technology</p><p>229</p><p>P</p><p>esticide A</p><p>pplication Technology</p><p>SELECT THE BEST EQUIPMENT/</p><p>NOZZLE TYPE FOR THE JOB</p><p>Although each component of the sprayer plays a role in achieving success</p><p>in pesticide application, nozzles may play the most significant role.</p><p>Nozzles come in a wide variety of types and sizes. Each nozzle type</p><p>is designed for a specific type of target and application. Most nozzle</p><p>manufacturers’ catalogs and websites have charts showing which nozzle</p><p>type will be best for a specific job. To choose the most appropriate nozzle</p><p>for a given situation, you will need to be aware of all the factors involved</p><p>in selecting the right nozzle. Any one of the factors listed below may be</p><p>the deciding factor when selecting the most appropriate nozzle for the</p><p>job on hand.</p><p>• Sprayer operation parameters (Application rate, spray pressure, travel</p><p>speed)</p><p>• Type of chemical sprayed (Herbicides, insecticides, fungicides,</p><p>fertilizers or growth regulators)</p><p>• Mode of action of chemical (Systemic, contact—for spray coverage</p><p>requirement)</p><p>• Application type (broadcast, band, directed, air-assisted)</p><p>• Spray drift risk</p><p>• Label requirements</p><p>CHOOSE THE MOST APPROPRIATE</p><p>NOZZLE SIZE</p><p>Once you determine the type of nozzle that will be best for a specific</p><p>spraying situation, next you need to determine the appropriate size of that</p><p>nozzle that will provide the application rates (gallons per acre) prescribed</p><p>by product labels under various operating conditions (spray pressures</p><p>and travel speeds).</p><p>Steps to select the proper nozzle size:</p><p>The following steps must be taken to determine the nozzle flow rate in</p><p>gallons per minute (gpm):</p><p>Step 1: Select the application rate in gallons per acre (gpa). This is a</p><p>management decision you will have to make based on pesticide label</p><p>recommendations, field conditions, and water supply.</p><p>Step 2: Select a practical and safe ground speed in miles per hour (mph).</p><p>Step 3: Determine the spray width per nozzle (W).</p><p>• For broadcast applications, W = nozzle spacing (distance between</p><p>two nozzles on the boom) in inches.</p><p>230</p><p>P</p><p>es</p><p>tic</p><p>id</p><p>e</p><p>A</p><p>pp</p><p>lic</p><p>at</p><p>io</p><p>n</p><p>Te</p><p>ch</p><p>no</p><p>lo</p><p>gy</p><p>230</p><p>P</p><p>es</p><p>tic</p><p>id</p><p>e</p><p>A</p><p>pp</p><p>lic</p><p>at</p><p>io</p><p>n</p><p>Te</p><p>ch</p><p>no</p><p>lo</p><p>gy</p><p>• For band spraying, W = band width in inches. For directed spraying,</p><p>W = row spacing in inches (or band width) divided by the number</p><p>of nozzles per row (or band).</p><p>Step 4: Determine the flow rate (gpm) required from each nozzle by using</p><p>the following equation:</p><p>gpm = gpa x mph x W</p><p>5940</p><p>Step 5: Select a nozzle size from the manufacturer’s catalog that will give</p><p>the flow rate (gpm) determined in step 4 when the nozzle is operated</p><p>within the recommended pressure range. If a nozzle of this size is not</p><p>available, change the travel speed in the equation above and determine</p><p>the new flow rate required.</p><p>More information on selecting the best nozzle type and size are given in</p><p>Ohio State University Extension fact sheet FABE-528, “Selecting the Best</p><p>Nozzle for the Job,” ohioline.osu.edu/factsheet/fabe-528.</p><p>Keep spray drift in mind when selecting nozzles</p><p>Although complete elimination of spray drift is impossible, problems</p><p>can be reduced significantly if you are aware of the major factors which</p><p>influence drift and take precautions to minimize their influence on off-</p><p>target movement of droplets. Drift is influenced by many factors which are</p><p>discussed in detail in Ohio State University Extension fact sheet FABE-525,</p><p>“Effect of Major Variables on Drift Distances of Spray Droplets,” available</p><p>at ohioline.osu.edu/factsheet/fabe-525. Here are some tips on how to</p><p>minimize spray drift:</p><p>1. Equipment, especially nozzles, used to spray pesticides play a</p><p>significant role in generating as well as reducing spray drift. Research</p><p>clearly indicates that nozzles labeled as “low-drift” significantly reduce</p><p>spray drift as discussed in Ohio State University Extension fact sheet</p><p>FABE-523 “Effectiveness of Turbodrop® and Turbo TeeJet® nozzles</p><p>in drift reduction,” ohioline.osu.edu/factsheet/fabe-523. If drift is, or</p><p>becomes a concern, it may be best to switch from a conventional flat-</p><p>fan nozzle to a “low-drift” flat-fan nozzle with the same flow rate. Keep</p><p>your nozzles as close to the target as possible while still producing a</p><p>uniform distribution of spray on the target.</p><p>2. Consider using a sprayer equipped with the air-assist technology on</p><p>the sprayer boom. When used under fully or partially developed crop</p><p>conditions, air flow coming out of the boom just behind the nozzles</p><p>carries the small, drift-prone droplets into the canopy where they can</p><p>be deposited.</p><p>3. There are “drift retardant” chemicals sold in the market that are</p><p>designed to increase the droplet size and reduce the number of very</p><p>small droplets when added to the spray mixture. This, however, should</p><p>be the last defense against drift. First consider the other options, such</p><p>http://ohioline.osu.edu/factsheet/fabe-528</p><p>http://ohioline.osu.edu/factsheet/fabe-525</p><p>http://ohioline.osu.edu/factsheet/fabe-523</p><p>231</p><p>P</p><p>esticide A</p><p>pplication Technology</p><p>231</p><p>P</p><p>esticide A</p><p>pplication Technology</p><p>as better targeting of the spray and switching to low-drift nozzles.</p><p>4. If weather conditions (wind speed and direction, humidity, temperature,</p><p>inversions) are not favorable, and there is any doubt about a spray job</p><p>that might result in drift, wait until there is no longer that element of</p><p>doubt. One good investment you can make is a wind meter that tells</p><p>the wind velocity at your location at the time of application.</p><p>Maximize pesticide deposit and coverage on the target</p><p>It is important to choose the nozzle and set up the application equipment</p><p>based on what it is that you are trying to control, and what part of the</p><p>plant canopy should be targeted when spraying to achieve effective pest</p><p>control. For example, when applying a fungicide to manage Fusarium head</p><p>blight or head scab of small grain, the target is the head and not the leaf.</p><p>When a fungicide is applied using nozzles that direct the spray downward,</p><p>most of the product is likely to deposit on the leaves or the ground and</p><p>not the head. On the other hand, when we are trying to control diseases</p><p>such as Soybean rust, the target should be the leaves, especially the ones</p><p>in the lower part of the canopy. Nozzle selection will have a significant</p><p>influence on whether or not the droplets sprayed will reach the specific</p><p>target site in the canopy.</p><p>The following trends have emerged from our multi-year studies on target</p><p>deposition:</p><p>• Use nozzles and equipment setup that provide medium spray quality</p><p>(approximately 250-350-micron diameter) for better penetration of</p><p>droplets into lower parts of both wheat and soybean canopies to</p><p>control aphids and diseases such as stem rot that normally start from</p><p>the lower part of the canopy.</p><p>• Single pattern flat-fan nozzles producing medium quality spray</p><p>tend to provide a better penetration of droplets inside soybean</p><p>canopy under dense canopy conditions.</p><p>• Under dense canopy conditions, flat fan nozzles provided better</p><p>coverage and penetration into the canopy than the hollow cone</p><p>nozzle.</p><p>• Spray hitting the target from two different angles using nozzles</p><p>producing twin spray patterns (such as TwinJet) produce better</p><p>coverage and deposition on upper parts of the soybean canopy, and</p><p>they may produce acceptable control of diseases in lower part of the</p><p>canopy if the canopy is not dense. In dense soybean canopy conditions,</p><p>twin pattern application setup had the lowest coverage and deposits</p><p>on lower parts of the canopy. So, using twin pattern nozzles, or a single</p><p>flat-fan nozzle tilted at a forward angle of 30 or 45 degrees from the</p><p>horizontal is definitely the best for application of fungicides for wheat</p><p>head scab, but will be</p><p>the worst setup for soybean insects and diseases,</p><p>such as aphids and Sclerotinia stem rot (white mold), respectively.</p><p>232</p><p>P</p><p>es</p><p>tic</p><p>id</p><p>e</p><p>A</p><p>pp</p><p>lic</p><p>at</p><p>io</p><p>n</p><p>Te</p><p>ch</p><p>no</p><p>lo</p><p>gy</p><p>232</p><p>P</p><p>es</p><p>tic</p><p>id</p><p>e</p><p>A</p><p>pp</p><p>lic</p><p>at</p><p>io</p><p>n</p><p>Te</p><p>ch</p><p>no</p><p>lo</p><p>gy</p><p>• If a twin-pattern nozzle is used, it is best to use some of the new</p><p>twin-flat pattern nozzles rather than the conventional TwinJet</p><p>nozzles because the conventional nozzles tend to produce a</p><p>higher number of extremely small droplets that tend to evaporate</p><p>or drift before having a chance to deposit on the target surface.</p><p>• Canopy conditions (tall, dense vs. short, light) and operating conditions</p><p>(air flow rate, air discharge angle, and proper droplet size) may affect the</p><p>performance of an air assist sprayer. However, in general, if operated</p><p>properly, when there is adequate canopy cover under the boom,</p><p>air-assisted sprayers will likely to do a better job with penetration of</p><p>droplets into canopy and spray coverage than a conventional sprayer. In</p><p>our studies, an air-assisted sprayer did a better job with penetration of</p><p>droplets into soybean canopy and spray coverage on the underside of</p><p>the leaves than a conventional sprayer, especially under dense canopy</p><p>conditions. However, it did not produce any noticeable advantages in</p><p>wheat (for scab and stem rust). In some cases it actually produced lower</p><p>deposits than the sprayers with conventional (no air assistance) nozzles.</p><p>Calibrate the sprayer</p><p>The primary goal with calibration is to determine the actual rate of</p><p>application in gallons per acre, then make adjustments if the difference</p><p>between the actual rate and the intended rate is greater or less than</p><p>5 percent of the intended rate. Although rate controllers can regulate</p><p>the flow rate of nozzles to keep the application rate constant, a manual</p><p>calibration at least once a year is needed to make sure the rate controller</p><p>is functioning properly.</p><p>Before starting calibration, make sure you have a good set of nozzles on</p><p>the sprayer. Nozzles wear through extended use causing overapplication,</p><p>or some nozzles or screens may become clogged causing under-</p><p>application. Clean all the clogged nozzles. Check the output of all the</p><p>nozzles for a given length of time at a given spray pressure. Compare</p><p>output from each nozzle’s output with the expected output shown in the</p><p>manufacturer’s catalog for that nozzle at the same pressure. Replace the</p><p>nozzles showing an output error of more than 10 percent of a new nozzle.</p><p>• Calibrating a sprayer involves taking only three specific measurements:</p><p>actual ground speed, the distance between nozzles, and nozzle flow</p><p>rate for a given length of time.</p><p>• Just three things are needed to take these measurements: a timer</p><p>showing seconds, a measuring tape, and a measuring cup graduated</p><p>in ounces.</p><p>• A mixture containing pesticides may have a slightly higher density</p><p>or viscosity and these may slightly change the flow rates of nozzles.</p><p>But usually the difference in flow rates between water alone and a</p><p>mixture containing pesticides is not significant unless liquid fertilizer</p><p>is the carrier.</p><p>233</p><p>P</p><p>esticide A</p><p>pplication Technology</p><p>233</p><p>P</p><p>esticide A</p><p>pplication Technology</p><p>There are several ways to calibrate a sprayer. One easy method, the</p><p>1/128th method, is explained in OSU Extension fact sheet FABE 520,</p><p>“Calibrating Boom Sprayers,” ohioline.osu.edu/factsheet/fabe-520. Here</p><p>is a brief summary of steps you will need to take when using this method:</p><p>1. Fill the sprayer tank (at least half full) with clean water.</p><p>2. Run the sprayer, inspect it for leaks, and make sure all vital parts</p><p>function properly.</p><p>3. Measure the distance in inches between the nozzles.</p><p>4. Determine the appropriate travel distance in the field based on this</p><p>nozzle spacing. The appropriate distances for different nozzle spacing</p><p>is as follows:</p><p>• 408 feet for 10-inch spacing,</p><p>• 272 feet for 15-inch spacing,</p><p>• 204 feet for 20-inch spacing,</p><p>• 136 feet for 30-inch spacing, and</p><p>• 102 feet for 40-inch spacing.</p><p>See Extension fact sheet FABE 520, ohioline.osu.edu/factsheet/fabe-</p><p>520, for travel distances for other nozzle spacings.</p><p>5. Drive the measured distance in the field at your normal spraying speed;</p><p>record the travel time in seconds. Repeat this procedure and average</p><p>the two measurements.</p><p>6. With the sprayer parked, run the sprayer at the same pressure level</p><p>and catch the output from each nozzle in a measuring cup for the travel</p><p>time required in step 5 above.</p><p>7. Calculate the average nozzle output by adding the individual outputs</p><p>and then dividing by the number of nozzles tested. The final average</p><p>nozzle output in ounces you get is equal to the application rate in</p><p>gallons per acre. For example, if you catch an average of 15 ounces</p><p>from a set of nozzles, the actual application rate of the sprayer is equal</p><p>to 15 gallons per acre.</p><p>8. Compare the actual application rate with the recommended or intended</p><p>rate. If the actual rate is more than 5 percent higher or lower than the</p><p>recommended or intended rate, you must make adjustments in either</p><p>spray pressure or travel speed or both.</p><p>• For example, to increase the flow rate, you will need to either slow</p><p>down or increase the spray pressure. The opposite is true when</p><p>you need to reduce application rate. As you make these changes,</p><p>stay within proper and safe operating condition of the sprayer.</p><p>Remember increased pressure will result in increasing the number</p><p>of small, drift-prone droplets. Follow the equations given in OSU</p><p>http://ohioline.osu.edu/factsheet/fabe-520</p><p>http://ohioline.osu.edu/factsheet/fabe-520</p><p>234</p><p>P</p><p>es</p><p>tic</p><p>id</p><p>e</p><p>A</p><p>pp</p><p>lic</p><p>at</p><p>io</p><p>n</p><p>Te</p><p>ch</p><p>no</p><p>lo</p><p>gy</p><p>234</p><p>P</p><p>es</p><p>tic</p><p>id</p><p>e</p><p>A</p><p>pp</p><p>lic</p><p>at</p><p>io</p><p>n</p><p>Te</p><p>ch</p><p>no</p><p>lo</p><p>gy</p><p>Extension fact sheet FABE-520 to find optimum travel speed and</p><p>pressure quickly.</p><p>9. Recalibrate the sprayer (repeat steps 5-8 above) until the recommended</p><p>application error of +5 percent or less is achieved.</p><p>Calibrating the sprayer only once at the beginning of the spraying season</p><p>is never enough. It should be done frequently throughout the season,</p><p>especially when changes occur in ground conditions or the topography</p><p>of the field sprayed changes.</p><p>When using this method, you may also want to calculate the actual travel</p><p>speed and compare it with what is displayed on the rate controller or the</p><p>tractor speedometer. Here is how you calculate the actual travel speed</p><p>in miles per hour (MPH):</p><p>Check uniformity of application</p><p>How the chemical is deposited on the target is as important as the amount</p><p>applied. Know the kind of nozzles on your sprayer and the need for</p><p>overlap for complete coverage. If spraying products directly on a target</p><p>then banding nozzles should be used. With this type of nozzle, the product</p><p>sprayed is evenly distributed across the spray pattern. However, when</p><p>making broadcast applications, the flat-fan nozzles used for this kind of</p><p>application produce heavy volume discharged from the center of the spray,</p><p>and the volume tapers off towards both end of the triangular-shaped spray</p><p>pattern. Therefore, spray patterns from adjacent nozzles must overlap, as</p><p>shown in the figure below, to obtain uniform coverage across the spray</p><p>swath. A low boom or a boom set too high will create a poor pattern and</p><p>misapplication. Check the nozzle catalog to determine the proper boom</p><p>height recommended for different nozzle types and spacings.</p><p>MPH = x</p><p>60</p><p>88</p><p>Feet traveled</p><p>Seconds to travel</p><p>235</p><p>P</p><p>esticide A</p><p>pplication Technology</p><p>235</p><p>P</p><p>esticide A</p><p>pplication Technology</p><p>Flat-flan nozzles used for broadcast spraying require 30-</p><p>50 percent overlap of spray patterns</p><p>Make sure the nozzles are not fully or partially clogged. Clogging will not</p><p>only change the flow rate, it also changes the spray pattern. Do not use</p><p>a pin, knife, or any other metal object to unclog nozzles. In addition to</p><p>clogging, mismatched nozzle tips on the boom, or uneven boom height</p><p>are the most common causes of non-uniform spray patterns.</p><p>They can all</p><p>cause streaks or untreated areas that result in insufficient pest control</p><p>and economic loss.</p><p>Know how to calculate how much chemical product to</p><p>mix in the tank</p><p>Labels give two types of application rates: volume of spray mixture</p><p>(pesticide and water) applied per unit area (gallons per acre, ounces per</p><p>1,000 square feet, etc.), and the amount of actual chemical applied per</p><p>unit area (ounces, pints, or quarts per acre or 1,000 square feet). The</p><p>first requirement can be attained by proper calibration and operation of</p><p>the sprayer. The second label recommendation not only requires proper</p><p>calibration and operation of the sprayer, but it also requires that the spray</p><p>mixture contains the right concentration of the actual product applied.</p><p>The amount of chemical needed per tankful depends on the recommended</p><p>rate and the size of area you intend to treat per tank of spray. Detailed</p><p>information on how to calculate the proper amount of chemical to add</p><p>to the spray tank is given in Ohio State University Extension fact sheet</p><p>FABE-530, ohioline.osu.edu/factsheet/fabe-530.</p><p>Read the Label!</p><p>In the past, labels on pesticides gave general statements when referring</p><p>to application equipment. Today, many labels are much more specific</p><p>on nozzle selection, pressure, and volume. In addition to satisfying the</p><p>gallon per acre requirement given on the label, you also need to satisfy</p><p>the droplet size requirement given on the label. For example, the nozzles</p><p>shown on the figure below all produce the same flow rate (0.2 gallons per</p><p>minute) at same or slightly different pressures, but each one provides a</p><p>different spray quality (droplet size). Check the information given in nozzle</p><p>manufacturers’ catalogs to make sure the nozzle will provide the required</p><p>spray quality under the conditions each nozzle will be operating (travel</p><p>speed, flow rate, pressure).</p><p>50%30%</p><p>http://ohioline.osu.edu/factsheet/fabe-530</p><p>236</p><p>P</p><p>es</p><p>tic</p><p>id</p><p>e</p><p>A</p><p>pp</p><p>lic</p><p>at</p><p>io</p><p>n</p><p>Te</p><p>ch</p><p>no</p><p>lo</p><p>gy</p><p>236</p><p>P</p><p>es</p><p>tic</p><p>id</p><p>e</p><p>A</p><p>pp</p><p>lic</p><p>at</p><p>io</p><p>n</p><p>Te</p><p>ch</p><p>no</p><p>lo</p><p>gy</p><p>EFFECTS OF NOZZLE TYPE ON COVERAGE</p><p>(Flow rate of each nozzle: 0.2 gal/min)</p><p>Twinjet</p><p>11002</p><p>XR 8002 Turbo Teejet</p><p>11002</p><p>Air-Induction</p><p>110015</p><p>Pressure</p><p>10 psi 40 psi 40 psi 70 psi</p><p>Spray Quality</p><p>Very Fine Fine Medium Coarse</p><p>TeeJet Technologies</p><p>APPROVED NOZZLES AND</p><p>OPERATING PRESSURES: 2,4-D AND</p><p>DICAMBA FORMULATIONS*</p><p>There are several new products containing 2,4-D and Dicamba. Each</p><p>product may have a different set of application requirements. For example,</p><p>the labels require a number of specific nozzles when using a product.</p><p>Therefore, applicators are advised to check the product labels to find out</p><p>specific nozzles required to apply these products, the range of operating</p><p>pressure required when using these nozzles, maximum and minimum</p><p>wind speed conditions limiting the application of these products, and the</p><p>widths of buffer zones required outside the application site depending on</p><p>the wind direction and the existence of sensitive crops nearby.</p><p>Applicators should refer to the company websites (below) for current</p><p>information on nozzles, tank mixing, and other application details:</p><p>Bayer: xtendimaxapplicationrequirements.com</p><p>BASF: engeniatankmix.com</p><p>Corteva: fexapanapplicationrequirements.dupont.com</p><p>http://xtendimaxapplicationrequirements.com</p><p>http://engeniatankmix.com</p><p>http://fexapanapplicationrequirements.dupont.com</p><p>237</p><p>P</p><p>esticide A</p><p>pplication Technology</p><p>237</p><p>P</p><p>esticide A</p><p>pplication Technology</p><p>SUMMARY</p><p>The information related to pesticide application presented here is rather</p><p>general. More specific and detailed information on the topic discussed in</p><p>this chapter of the guide can be found in Ohio State University Extension</p><p>fact sheet FABE-527, “Best Management Practices for Boom Spraying,”</p><p>ohioline.osu.edu/factsheet/fabe-527. Here are the key general and</p><p>specific recommendations discussed in this publication:</p><p>• Carefully read and follow the specific recommendations given on</p><p>the pesticide label and in the nozzle catalogs and sprayer operator’s</p><p>manual.</p><p>• Calibrate the sprayer to make sure that the amount recommended on</p><p>the label is applied.</p><p>• Check the sprayer setup to make sure the amount sprayed is distributed</p><p>evenly across the spray swath.</p><p>• Operate the nozzles at a pressure that will allow them to produce the</p><p>spray quality (droplet size) recommended in the product label.</p><p>• For best results, keep the spray volume (application rate) above 15 gpa</p><p>for ground and 5 gpa for aerial applications.</p><p>• Slow down when spraying. Spray coverage is usually improved at</p><p>slower speeds. Also, it is proven that the higher the travel speed, the</p><p>greater likelihood of drift.</p><p>• To improve coverage, if applicable, use directed spraying.</p><p>• Probability of spray drift is much greater when using fine to medium</p><p>droplets than coarser droplets used for application of some other types</p><p>of pesticides such as herbicides.</p><p>• For herbicide applications, flat-fan nozzles are better than cone nozzles</p><p>to produce a much smaller proportion of extremely small, drift-prone</p><p>droplets.</p><p>• Coverage to just the top of the canopy may be sufficient for adequate</p><p>control with some products. However, both horizontal and vertical</p><p>coverage of the plant may be absolutely necessary for other situations</p><p>such as disease and insects that may be hidden in dense canopies.</p><p>• Air-assisted sprayers usually provide better coverage and droplet</p><p>penetration into the canopy than conventional sprayers when there is</p><p>a full, dense canopy such as in soybeans sprayed late season.</p><p>• Be careful when using twin nozzle/pattern technology. Two nozzles (or</p><p>spray patterns) angled (one forward, one backward) work better when</p><p>the canopy is not dense and tall—weeds for example.</p><p>• Be safe. Wear protective clothing, goggles and rubber gloves, and</p><p>respirators if required on the label when calibrating the sprayer, doing</p><p>the actual spraying, and cleaning the equipment.</p><p>http://ohioline.osu.edu/factsheet/fabe-527</p><p>238</p><p>P</p><p>es</p><p>tic</p><p>id</p><p>e</p><p>A</p><p>pp</p><p>lic</p><p>at</p><p>io</p><p>n</p><p>Te</p><p>ch</p><p>no</p><p>lo</p><p>gy</p><p>238</p><p>P</p><p>es</p><p>tic</p><p>id</p><p>e</p><p>A</p><p>pp</p><p>lic</p><p>at</p><p>io</p><p>n</p><p>Te</p><p>ch</p><p>no</p><p>lo</p><p>gy</p><p>CALIBRATING GRANULAR APPLICATORS</p><p>Application rates and settings for insecticide metering units on planter</p><p>hoppers are usually given on the chemical label. However, correct rates</p><p>can be attained only if the application units are calibrated properly because</p><p>each insecticide flows differently depending on its density, particle size,</p><p>type of carrier used, and relative humidity. Therefore, the setting used for</p><p>one 15G product may not be the same as that needed for another 15G.</p><p>Follow steps below to calibrate your applicator.</p><p>1. Read the label and determine the rate of material you want to apply.</p><p>For corn rootworms, this is often given in terms such as—</p><p>• 1.2 oz. a.i./1000 row ft.</p><p>• 8 oz. of a 15G, or 6 oz. of a 20G formulation/1000 row ft.</p><p>• 4 oz. of a 3G at 0.12 oz. a.i./1000 row ft.</p><p>2. Fill the insecticide boxes and attach a plastic bag or a calibration tube</p><p>to each applicator tube.</p><p>3. Open the metering units to a beginning setting such as the previous</p><p>year’s setting or setting suggested on the insecticide label.</p><p>4. Measure out 250 feet and operate the planter at planting speed over</p><p>this distance. Collect the granules.</p><p>5. Weigh the amount collected, or use a calibration tube provided by</p><p>the product manufacturer to determine the weight per 250 row feet.</p><p>6. Multiply the amount collected by 4 to determine amount per 1000 row</p><p>feet. Compare this with the recommended amount per 1000 feet of row.</p><p>7. Repeat steps 1 through 6 above until the difference between the desired</p><p>(intended) rate and the measured rate in step 6 is less than 5 percent</p><p>of the intended rate.</p><p>239</p><p>P</p><p>esticide A</p><p>pplication Technology</p><p>239</p><p>P</p><p>esticide A</p><p>pplication Technology</p><p>NOZZLE TYPES FOR USE</p><p>ON FIELD CROPS</p><p>Type Suggested Use Recommended</p><p>PSI</p><p>Spray Pattern</p><p>Type</p><p>Hollow</p><p>cone</p><p>Most contact</p><p>insecticides</p><p>and fungicides;</p><p>postemergence</p><p>banding of</p><p>herbicides</p><p>60 psi and above;</p><p>below 40 psi if for</p><p>weed control</p><p>Circular—light</p><p>applications</p><p>in center, fine</p><p>droplets</p><p>Flat fan</p><p>Pre- and</p><p>postemergence</p><p>herbicide and</p><p>some insecticides</p><p>and fungicides</p><p>15-60 psi, not over</p><p>40 psi for weed</p><p>spraying</p><p>Fan-like pattern of</p><p>medium droplets</p><p>Even-flat</p><p>Banding</p><p>herbicides,</p><p>insecticides,</p><p>fungicides</p><p>20 to 40 psi</p><p>Uniform coverage</p><p>across spray</p><p>pattern, medium</p><p>droplets</p><p>Flooding</p><p>flat</p><p>Pre- and</p><p>postemergence</p><p>herbicides where</p><p>drift is hazardous</p><p>10-20 psi for</p><p>max drift control;</p><p>below 30 psi</p><p>otherwise</p><p>Fan-like, coarse</p><p>droplets,</p><p>numerous enough</p><p>for weeds</p><p>Full cone,</p><p>Raindrop</p><p>Pre-plant soil</p><p>incorporated</p><p>15-40 psi</p><p>Full cone or</p><p>hollow cone (with</p><p>Raindrop); large</p><p>droplets</p><p>Boomless</p><p>Weed and</p><p>brush control in</p><p>pastures, fence</p><p>row and roadsides</p><p>10-30 psi, never</p><p>over 40 psi</p><p>Fan-like, extra</p><p>wide flat spray</p><p>pattern with 18 to</p><p>33 feet coverage</p><p>240</p><p>P</p><p>es</p><p>tic</p><p>id</p><p>e</p><p>A</p><p>pp</p><p>lic</p><p>at</p><p>io</p><p>n</p><p>Te</p><p>ch</p><p>no</p><p>lo</p><p>gy</p><p>240</p><p>P</p><p>es</p><p>tic</p><p>id</p><p>e</p><p>A</p><p>pp</p><p>lic</p><p>at</p><p>io</p><p>n</p><p>Te</p><p>ch</p><p>no</p><p>lo</p><p>gy</p><p>EVEN FLAT-FAN NOZZLE HEIGHT</p><p>FOR VARIOUS BAND WIDTHS</p><p>Band Width</p><p>(inches)</p><p>Approximate Nozzle Height (inches)</p><p>80 Series 95 Series</p><p>8 5 4</p><p>10 6 5</p><p>12 7 6</p><p>14 8 7</p><p>Example: If you desire a 10-inch band from a nozzle with 80 spray</p><p>angle, mount nozzle 6 inches above the surface.</p><p>FLAT-FAN NOZZLE HEIGHT FOR</p><p>VARIOUS SPRAY PATTERN ANGLES</p><p>Spray Pattern Angle</p><p>Nozzle Height above Crop (inches)</p><p>20-inch spacing 30-inch spacing</p><p>65 22 to 24 33 to 35</p><p>80 17 to 19 26 to 28</p><p>110 15 to 18 20 to 22</p><p>Example: For a spray tip with an 80 spray pattern and spaced 20 inches</p><p>apart, the correct nozzle height above the crop canopy is 17-19 inches.</p><p>RELATIVE WEAR OF NOZZLE</p><p>MATERIALS*</p><p>Material Wear Life (years)</p><p>Brass 1</p><p>Nylon 3-4</p><p>Plastic 3-5</p><p>Stainless Steel 4-6</p><p>Hardened Stainless Steel 8-10</p><p>Ceramic 10-15</p><p>*Actual life will depend on usage. Calibrate your spraying system frequently.</p><p>241</p><p>P</p><p>esticide A</p><p>pplication Technology</p><p>241</p><p>P</p><p>esticide A</p><p>pplication Technology</p><p>FUNGICIDE APPLICATION</p><p>TECHNOLOGY FOR HEAD SCAB</p><p>MANAGEMENT</p><p>When applying a fungicide to manage Fusarium head blight or head scab</p><p>of small grain, the target is the head and not the leaf. Traditional fungicide</p><p>application techniques suitable for managing foliar diseases do not provide</p><p>adequate coverage of the heads, and as such, do not provide adequate</p><p>suppression of head scab and vomitoxin. When a fungicide is applied</p><p>using nozzles that direct the spray downward, most of the product is</p><p>deposited on the leaves or the ground and not the head. Hence, specific</p><p>ground application guidelines have been developed to improve fungicide</p><p>coverage and efficacy when managing head scab.</p><p>Nozzle Orientation. Set flat-fan nozzles at a forward angle of 30 or 45</p><p>degrees from the horizontal. When applying a fungicide at travel speeds</p><p>of 6 mph or above, forward-facing nozzles provide better spray deposition</p><p>and scab management than downward-facing nozzles. An air-assisted</p><p>spray system can also be used to achieve a forward-oriented spray setup,</p><p>if the air orifices are angled forward to about 45 degrees. The air stream</p><p>pushes the heads forward from their vertical position to an angle that</p><p>improves spray deposition.</p><p>Droplet Size. Use 80-degree flat-fan nozzles to produce large fine to</p><p>small medium droplets of 300 to 350 microns. At travel speeds of 6 mph</p><p>or higher, these droplets are fine enough to provide even distribution</p><p>of the fungicide on the heads, while at the same time, large enough to</p><p>minimize spray drift.</p><p>Water Volume. A spray volume of 10 gpa results in scab and vomitoxin</p><p>suppression comparable to, or better than, a volume of 20 gpa, with a</p><p>single set of angled flat-fan nozzles. Coverage with 10 gpa is less than that</p><p>achieved with 20 gpa, but the amount of fungicide deposited on the head</p><p>is greater at 10 gpa than at 20 gpa because the fungicide concentration</p><p>in 10 gpa is double the concentration in 20 gpa.</p><p>Height of the Nozzles above the Canopy. Angled spray nozzles should</p><p>be positioned 8 to 10 inches above the grain heads.</p><p>It is not necessary to modify the entire boom to achieve the 30 to 45</p><p>degree nozzle orientation. Nozzle body adapters, 45-degree nozzle caps,</p><p>or single-swivel nozzle adapters can be used to generate a forward-angled</p><p>spray pattern.</p><p>Source: mawg.cropdisease.com/pdf/AE-1314_Ground_Application_of_</p><p>Fungicides_REVISED.pdf</p><p>agbiopubs.sdstate.edu/articles/FS919.pdf</p><p>http://mawg.cropdisease.com/pdf/AE-1314_Ground_Application_of_Fungicides_REVISED.pdf</p><p>http://mawg.cropdisease.com/pdf/AE-1314_Ground_Application_of_Fungicides_REVISED.pdf</p><p>http://agbiopubs.sdstate.edu/articles/FS919.pdf</p><p>242</p><p>P</p><p>es</p><p>tic</p><p>id</p><p>e</p><p>A</p><p>pp</p><p>lic</p><p>at</p><p>io</p><p>n</p><p>Te</p><p>ch</p><p>no</p><p>lo</p><p>gy</p><p>242</p><p>P</p><p>es</p><p>tic</p><p>id</p><p>e</p><p>A</p><p>pp</p><p>lic</p><p>at</p><p>io</p><p>n</p><p>Te</p><p>ch</p><p>no</p><p>lo</p><p>gy</p><p>CALIBRATION EQUATIONS FOR</p><p>LIQUID APPLICATIONS</p><p>To double nozzle flow rate, pressure must increase four times.</p><p>Pressure cannot be used to make major changes in rate, only minor</p><p>changes due to nozzle wear and other factors.</p><p>Doubling the ground speed of a sprayer reduces the gallons per acre</p><p>(GPA) by a half.</p><p>Doubling the effective spray width per nozzle decreases the GPA by</p><p>one-half.</p><p>GPA = GPM x 5940</p><p>MPH x W</p><p>GPM =</p><p>GPA x MPH x W</p><p>5940</p><p>OPM = GPM x 128</p><p>MPH =</p><p>feet traveled x 60</p><p>sec. to travel x 88</p><p>GPA = gallons per acre</p><p>GPM = gallons per minute</p><p>OPM = ounces per minute</p><p>MPH = miles per hour</p><p>W = nozzle spacing in inches (broadcast spraying)</p><p>Some pesticides may be sold in formulations that contain different amounts</p><p>of the same active ingredient. Therefore, manufacturers may give the</p><p>rate in terms of active ingredient (a.i.) per acre or 1000 feet of row. To</p><p>determine the actual application rate of actual formulated product, use</p><p>the following formula:</p><p>For dry products:</p><p>lb product per acre =</p><p>lb a.i. per acre X 100</p><p>% a.i. in product</p><p>243</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>243</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>GENERAL CROP</p><p>MANAGEMENT</p><p>244</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>244</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>SAMPLING</p><p>SUBMITTING INSECT SAMPLES</p><p>SENDING INSECTS FOR IDENTIFICATION</p><p>1. Soft bodied specimens, such as caterpillars, aphids, thrips, maggots,</p><p>and grubs are best preserved by placing them in a small bottle of</p><p>alcohol, either 70 percent ethyl or isopropyl, or clear 100 proof liquor.</p><p>Please do not send in water or formaldehyde.</p><p>2. Moths, butterflies, and large, fragile insects should be packed with</p><p>cotton or soft tissue in a box so the scales and other fragile parts aren’t</p><p>destroyed. Beetles, wasps, flies, and true bugs can be preserved in</p><p>alcohol or wrapped carefully in a box. Make sure that the insects won’t</p><p>crush.</p><p>3. Do not ship live insects, tape insects to paper, or place them loose in</p><p>a box or envelope.</p><p>SENDING INSECT-DAMAGED OBJECT FOR</p><p>PEST ID</p><p>1. Pack grain, pieces of wood, or other material in box. Be generous</p><p>with size of sample. If a plant is affected, pack the leaves or branches in</p><p>newspaper or foil and pack firmly in a box. If the root has been bored,</p><p>dig the plant and place the roots and attached soil in plastic. Do not</p><p>put leaves or soft tissue in plastic, as they rot quickly.</p><p>How to Send an Insect Sample</p><p>• Complete a laboratory specimen form (available from your Extension</p><p>office) or send a letter with inquirer’s name, address, telephone, and</p><p>information about the sample. Include the location of the insect if in or</p><p>on a plant, name the plant; write the number of pests seen, and type</p><p>of damaged observed.</p><p>Where to Send an Insect Sample</p><p>Ohio: C. Wayne Ellett Plant and Pest Diagnostic Clinic</p><p>The Ohio State University</p><p>8995 E. Main Street, Bldg. 23</p><p>Reynoldsburg, OH 43068-3399</p><p>See website for additional instructions and fees: ppdc.osu.edu</p><p>Pennsylvania: Michael Skvarla</p><p>Insect Identification Laboratory</p><p>501 Agricultural Sciences and Industries Building</p><p>University Park, PA 16802</p><p>http://ppdc.osu.edu</p><p>245</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>245</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>SUBMITTING PLANT SAMPLES</p><p>FOR DISEASE AND DISORDER</p><p>DIAGNOSIS</p><p>PLANT DISEASE OR DISORDERS</p><p>1. Select material showing the symptoms, showing a range of symptoms</p><p>from early to middle stages of development. Do not send completely</p><p>dead plants. Do not add water. Gently shake off any excess water</p><p>before packaging.</p><p>2. Send entire plant including roots. Include multiple plants. Dig the</p><p>entire plant, then place the roots and attached soil in a plastic bag</p><p>or wrap the roots and soil in foil or plastic wrap to keep the soil from</p><p>contaminating the foliage and to sustain the plant during transit. Do</p><p>not send wet plants, nor put leaves or soft tissue in plastic as they rot</p><p>quickly.</p><p>HERBICIDE INJURY SYMPTOMS</p><p>1. The disease diagnostic laboratories do not test plant material for</p><p>chemical residues. The laboratories evaluate the symptoms and the</p><p>background information provided, then determine if the material applied</p><p>may have caused the observed symptoms. For chemical residue testing,</p><p>contact your Extension educator.</p><p>PACKAGING AND DELIVERY OF DISEASE AND</p><p>DISORDER SPECIMENS</p><p>1. Send whole plant samples. Wrap the roots in a plastic bag or foil to</p><p>keep the soil on the roots.</p><p>2. Complete a specimen form available from your Extension office, or</p><p>contact the diagnostic laboratory (next page). Include information about</p><p>the sample such as when the damage occurred and a description of</p><p>symptoms of concern. The variety, previous crop, amount of sun and</p><p>moisture and soil type is also valuable information. Describe the local</p><p>weather when the symptoms appeared and the dates, rates, and</p><p>amounts of pesticides and fertilizers applied.</p><p>3. Use overnight mail services, or mail early in the week to avoid layovers</p><p>at the shipping facility. Call the lab if you are planning to deliver the</p><p>sample.</p><p>246</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>246</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>WHERE TO SEND A PLANT DISEASE AND</p><p>DISORDER SAMPLE</p><p>Ohio: C. Wayne Ellett Plant and Pest Diagnostic Clinic</p><p>The Ohio State University</p><p>8995 E. Main Street, Bldg. 23</p><p>Reynoldsburg, OH 43068-3399</p><p>Ph: 614-292-5006</p><p>See website for additional instructions and fees: ppdc.osu.edu</p><p>Pennsylvania: Sara R. May</p><p>Plant Disease Clinic</p><p>220 Buckhout Lab</p><p>University Park, PA 16802</p><p>Ph: 814-865-2204</p><p>plantpath.psu.edu/facilities/plant-disease-clinic</p><p>NEMATODE SAMPLES</p><p>Most nematodes are detected through soil samples which should be taken</p><p>from May to October when soil temperatures are at least 50 degrees</p><p>Fahrenheit at a 6 inch depth.</p><p>Do not sample very wet or dry soils. Samples should be taken from problem</p><p>areas of the field. Using a 1-inch soil sampling tube, trowel, or shovel take at</p><p>least 20 samples at a 6 inch depth from each sampling area (approximately</p><p>1 acre). Gently mix the samples in a bucket and place 1 quart of soil in a</p><p>plastic bag which can be clearly labeled. While soybean cyst nematode</p><p>eggs can be sampled during the season and after harvest, corn nematode</p><p>populations are best detected during the growing season while the corn</p><p>crop is in the field. Dig feeder roots to include in the sample if crop plants</p><p>are growing in the area. Never allow the sample to become dry or hot.</p><p>PACKAGING AND DELIVERY OF</p><p>NEMATODE SAMPLES</p><p>1. Complete a specimen form available from your Extension office or</p><p>contact the diagnostic laboratory (contact information below).</p><p>2. Soil samples should be sealed in a plastic bag. The bag should be</p><p>clearly labeled with the field identification and samples should be</p><p>packed into a box with sufficient packing material that the bags do not</p><p>shift or break open in transit.</p><p>http://ppdc.osu.edu</p><p>http://plantpath.psu.edu/facilities/plant-disease-clinic</p><p>247</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>247</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>WHERE TO SEND NEMATODE SAMPLES</p><p>Ohio: C. Wayne Ellett Plant and Pest Diagnostic Clinic</p><p>The Ohio State University</p><p>8995 E. Main Street, Bldg. 23</p><p>Reynoldsburg, OH 43068-3399</p><p>Ph: 614-292-5006</p><p>See website for additional instructions and fees: ppdc.osu.edu</p><p>Pennsylvania State University does not process field crop samples for</p><p>nematode analysis.</p><p>DIGITAL SAMPLES (IMAGES)</p><p>Images of the symptoms in the field are very helpful and can add</p><p>substantially to the diagnostic process.</p><p>In Pennsylvania, images can be sent as a supplement to a physical sample</p><p>by printing and mailing the image along with the sample, or emailing the</p><p>sample to Sara May at srm183@psu.edu.</p><p>In Ohio, images can be sent as a stand-alone digital sample to ppdc@</p><p>osu.edu. If, after examining the images, a physical sample is required, the</p><p>basic sample fee is waived for physical sample.</p><p>http://ppdc.osu.edu</p><p>248</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>248</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>SAMPLING GRAIN FOR</p><p>MYCOTOXIN ANALYSIS</p><p>The number of ears or heads infected within a field and the number of</p><p>infected kernels on a given ear or head are highly variable. As a result,</p><p>infected kernels and mycotoxin levels vary considerably within a grain</p><p>lot. There are always “hot spots” within the lot and these may affect the</p><p>accuracy of sampling and testing for toxins. Poor sampling could lead to</p><p>the rejection of grain with toxin levels below accepted thresholds or the</p><p>acceptance of grain with toxin above threshold. If a single sample is drawn</p><p>from a hot spot, the level of toxin contamination will be overestimated.</p><p>Conversely, if the sample misses the hot spots completely, toxin</p><p>contamination will be underestimated.</p><p>• To collect a representative grain sample, five to 10 samples should</p><p>be randomly collected from multiple locations in the bin or truckload.</p><p>• Air (suction) probes are not recommended when sampling moldy or</p><p>scabby grain for mycotoxin analysis. Diseased and broken kernels</p><p>are usually lighter in weight and contain higher levels of toxin than</p><p>wholesome kernels. Suction probes will likely pull these diseased</p><p>kernels and fines, resulting in an overestimation of toxin contamination</p><p>of the lot.</p><p>• For end-gate sampling, samples should be drawn from the entire width</p><p>and depth of the grain stream.</p><p>• Clean the samples to remove fines, and grind the grain to resemble</p><p>flour in a clean grinder.</p><p>249</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>249</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>COLLECTING A SOIL SAMPLE FOR</p><p>SOIL TESTING</p><p>Good general soil sampling methods for both Ohio and Pennsylvania.</p><p>• Do not wait until the last minute. The best time to sample is in the</p><p>summer or fall.</p><p>• Take cores from at least 15 to 20 spots randomly over the field to obtain</p><p>a representative sample. If the field has a history of banded nutrients,</p><p>take 25 cores per sample. One sample should not represent more</p><p>than 20 acres.</p><p>• Sample between rows. Avoid old fence rows, dead furrows, and other</p><p>spots that are not representative of the whole field.</p><p>• Take separate samples from problem areas if they can be treated</p><p>separately.</p><p>• In cultivated fields, sample to plow depth, typically 6-8 inches even in no-</p><p>till fields. Ohio (Tri-State Fertilizer Recommendations) recommendations</p><p>are based on soil samples collected to a depth of 8 inches, but let the</p><p>lab know the depth of sampling in any case.</p><p>• For Ohio—If sampling no-till fields, 4-inch samples should also be</p><p>collected for determination of a lime recommendation.</p><p>• For Pennsylvania—Take two samples from no-till fields: one to a 6 inch</p><p>depth for lime and fertilizer recommendations, and one to a 2 inch</p><p>depth to monitor surface acidity. For pH in the 2 inch depth, a sample</p><p>can be sent separately to the lab or checked with a field pH test kit.</p><p>If the plow depth sample does not indicate a need for limestone and</p><p>the surface pH is below 6.2, apply 2,000 lbs/A of calcium carbonate</p><p>equivalent. This amount should be adequate to neutralize the acidity</p><p>created by the surface-applied nitrogen fertilizer.</p><p>• Sample permanent pastures to a 3 to 4 inch depth.</p><p>• Collect the samples in a clean container.</p><p>• Mix the core samplings, allow to air dry, and remove roots and stones.</p><p>• Fill the soil test mailing container.</p><p>• Complete the information sheet,</p><p>giving all of the information requested.</p><p>Be sure to include the soil name. Remember, the recommendations</p><p>can be only as good as the information supplied.</p><p>250</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>250</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>SOIL SAMPLING IN NO-TILL</p><p>Research indicates that phosphorous (P) and potassium (K) layers or</p><p>concentrates near the soil surface in no-tillage and reduced tillage systems.</p><p>Because of this stratification of nutrients, split sampling can be used to</p><p>see if corrective action is necessary.</p><p>The routine method of sampling no-tillage fields is as follows:</p><p>a. 0–2 inch sample to check for soil pH and lime requirement. When</p><p>nitrogen fertilizers such as urea or (UAN) solutions are applied to the</p><p>surface in no-till systems, the surface few inches can become acid very</p><p>quickly. This can affect both herbicide activity and plant growth.</p><p>b. 0–8 inch sample to check for all nutrient requirements. Sample can be</p><p>split into a top 4-inch section and a bottom 4-inch section if so desired.</p><p>P AND K SOIL TEST LEVELS FOUND AT VARIOUS</p><p>DEPTHS IN THE SOIL (CRUZ, 1982)</p><p>Depth Plow Chisel No-till Plow Chisel No-till</p><p>inches Bray P1 (ppm) Exch. K (ppm)</p><p>0–3 37 85 90 150 230 285</p><p>3–6 47 35 27 165 105 100</p><p>6–9 30 15 18 140 100 100</p><p>9–12 8 8 8 100 100 100</p><p>PLANT TISSUE ANALYSIS</p><p>Plant tissue analysis is a valuable tool for nutrient management. It can</p><p>verify the success of a soil fertility program or uncover potential problems.</p><p>Plant tissue analysis complements soil testing by providing additional</p><p>information. While soil testing is used to predict availability of soil nutrients</p><p>and the need for fertilizers, plant tissue analysis measures the nutrients</p><p>actually taken up by the plant. In addition, the sufficiency of nitrogen, sulfur,</p><p>and micronutrients (e.g., zinc, and boron) are more reliably measured by</p><p>plant tissue analysis than soil testing.</p><p>Plant tissue analysis is frequently used for problem solving, to diagnose</p><p>or verify suspected nutrient deficiencies where visual symptoms are</p><p>observed. Plant tissue analysis can also be an economically viable tool</p><p>used to fine tune fertilizer applications. Samples collected for routine</p><p>monitoring of nutrient status can identify hidden hunger, where nutrient</p><p>deficiencies are not so severe that they cause obvious visual symptoms,</p><p>but levels are low enough to reduce crop performance. It should be</p><p>noted that plant nutrient content represents the effects of not only soil</p><p>nutrient status but also all the factors controlling plant growth. Therefore,</p><p>a single year’s information may not be useful for planning a soil fertility</p><p>251</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>251</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>management program. As results are accumulated over a period of years,</p><p>the information becomes more valuable.</p><p>Sample collection for plant tissue analysis is very important. The nutrient</p><p>concentration in a plant varies with the plant’s age and the part of the plant</p><p>sampled. If plant analyses are to be meaningful, the appropriate plant part</p><p>must be collected for the age of the plant, and a number of plants must be</p><p>included to obtain a representative sample to submit to the lab. Specific</p><p>directions on plant sampling generally are available with each sampling</p><p>kit from the laboratory. Try to avoid sampling crops damaged by insects,</p><p>disease, drought, or other adverse conditions. Environmental conditions</p><p>should always be noted when collecting samples.</p><p>When using plant tissue analyses to diagnose suspected crop nutritional</p><p>problems, it is a good idea to collect samples from both affected plants</p><p>in the problem area and reference plants in a nearby "normal" area</p><p>for comparison. Paired sampling is especially useful when collecting</p><p>diagnostic samples for a crop that is at a growth stage with no reference</p><p>sufficiency ranges.</p><p>When collecting diagnostic samples, it is critical that the same plant part</p><p>be sampled at the same time from both the problem and normal areas.</p><p>When the problem is encountered at a growth stage when there are no</p><p>sampling guidelines, young seedlings should be sampled by collecting</p><p>the entire plant 1 inch above the soil surface, while larger plants should</p><p>be sampled by collecting the most recently mature or fully expanded leaf.</p><p>Collecting paired soil samples from good and bad areas can also be</p><p>helpful. Gather as much information as possible, including growing</p><p>conditions, crop development stage, location of symptoms on the plant</p><p>(old versus new growth), landscape position of normal and problem areas,</p><p>etc. This information may provide important clues to help identify the cause</p><p>of the symptoms. Digital pictures of the whole field, the problem area in</p><p>the field, a whole plant, and a close-up of the leaf symptoms can be very</p><p>helpful when asking for assistance in diagnosing a problem.</p><p>Keep in mind that not all nutrient deficiencies in plants are the result of</p><p>nutrient deficiencies in the soil. Soil testing and plant analysis can confirm</p><p>each other, but they also can indicate when the cause of the problem is</p><p>something other than a nutrient deficiency in the soil. If the soil test level</p><p>is optimum, but the plants are deficient, some other factor is limiting</p><p>the plants’ ability to take up available nutrients. Some areas to consider</p><p>include: possible interactions with other cultural practices such as tillage</p><p>or pesticide use; pest injury such as rootworm feeding; differences in</p><p>varieties or hybrids; or soil physical conditions such as compaction.</p><p>252</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>252</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>PLANT PART TO SAMPLE FOR</p><p>FOLIAR SAMPLES</p><p>Crop Sample Prior to</p><p>or During</p><p>Plant Part to</p><p>Sample</p><p>Number of</p><p>Plants to</p><p>Sample</p><p>Corn Seedling stage</p><p>Above ground</p><p>portion</p><p>10</p><p>Corn Tasseling</p><p>Upper fully</p><p>developed leaf</p><p>10</p><p>Corn Initial silk Ear leaf 10</p><p>Soybeans Seedling stage</p><p>Above ground</p><p>portion</p><p>10</p><p>Soybeans Initial flowering</p><p>Upper fully</p><p>developed leaf</p><p>15</p><p>Small grains Initial bloom Upper leaves 20</p><p>Forage grasses Initial bloom Upper leaves 20</p><p>Alfalfa Initial flowering Top 6 inches 20</p><p>Forage legumes Initial flowering Top 6 inches 20</p><p>253</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>253</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>SAMPLING MANURE</p><p>Book values for manure nutrient content are good on average for a given</p><p>type of manure, but there is tremendous variation from farm to farm and</p><p>year to year due to differences in diet and feeding programs, type and</p><p>amount of bedding, the amount of rain or wash water added, manure</p><p>handling, and manure storage, etc. Proper sampling and analysis is the only</p><p>way to obtain farm-specific manure nutrient content and avoid the adverse</p><p>impacts of over- or under-application of manure nutrients. Following are</p><p>some guidelines for sampling manure:</p><p>• Because the goal is to collect a sample that represents the manure</p><p>actually being applied, the best time to sample is during loading or</p><p>field application. There is one disadvantage to sampling at spreading</p><p>time, the analysis results from samples collected at this time will not</p><p>be available to calculate manure application rates for that application.</p><p>However, the results can be used to calculate future application rates.</p><p>It is recommended that the manure nutrient content values used in</p><p>calculating manure application rates be based on running averages</p><p>or baseline values.</p><p>• Collect a representative composite manure sample from multiple</p><p>subsamples (5-10) taken as the manure is loaded for spreading. A</p><p>subsample can be collected every so often from different loads and put</p><p>into a 5-gallon bucket after sufficient subsamples have been collected,</p><p>the manure in the bucket is mixed and a subsample taken from that</p><p>to send to the lab.</p><p>• Because there can be significant stratification within a liquid storage, if</p><p>agitation is not thorough, it may be necessary to take several separate</p><p>samples to adequately represent the manure in the storage. If there</p><p>are obvious changes in manure</p><p>consistency as the storage is emptied,</p><p>a new separate composite sample should be started.</p><p>• Sampling manure in a storage, bedded pack, or stack is very difficult</p><p>to get a representative sample.</p><p>― Stock piles of litter or compost can be sampled by taking cores</p><p>that go at least 18 inches into the pile. A large auger or soil sample</p><p>tube may work for this. If using a shovel, dig well into the pile. The</p><p>pile should be sampled at least 10-20 locations. The cores should</p><p>be mixed and a subsample taken from this to send to the lab.</p><p>― Liquid manure storages are even more difficult to get a</p><p>representative sample from the storage. First, there can be</p><p>significant stratification in a liquid storage. Therefore, the storage</p><p>should be thoroughly agitated before sampling. Collecting the</p><p>sample is another challenge. Generally, there is limited success</p><p>with using pipes, buckets on rope, or a can on the end of a long</p><p>stick when trying to obtain a truly representative sample.</p><p>254</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>254</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>― Sampling litter in a poultry barn is similar to soil sampling.</p><p>Representative cores to the depth of the letter are collected across</p><p>the house and composited to obtain a sample to send to the lab.</p><p>Be aware that there will be major differences around feeders and</p><p>waterers.</p><p>• Once the sample is collected, follow instructions from the lab for sample</p><p>handling. Proper care and handling of the sample will ensure that the</p><p>samples sent for analysis are representative of the original manure</p><p>nutrient content. Proper steps should be taken to avoid leakage,</p><p>nutrient transformations such as volatilization, and moisture loss.</p><p>― Sample containers should never be filled more than three-</p><p>quarters full.</p><p>― For solid manure submitted in a plastic bag, fill approximately half</p><p>full and then squeeze the air out before sealing the bag.</p><p>― Keep the samples cool or freeze them, especially if there will be</p><p>a delay in getting them to the lab.</p><p>― It is usually best to send samples to the lab early in the week so</p><p>that they do not sit around over a weekend.</p><p>• Choose a reputable manure analysis lab that will provide the minimum</p><p>recommended tests:</p><p>― Percentage of moisture or solids</p><p>― Total and Ammonium N</p><p>― Total P</p><p>― Total K</p><p>― Other analyses that may be useful in some situations include</p><p>pH, carbon-to-nitrogen (C:N) ratio (compost), water-extractable P</p><p>(environmental testing), calcium carbonate equivalent (poultry layer</p><p>manure), secondary nutrients (Ca, Mg, and S), and micronutrients</p><p>(Cl, Na, Cu, Mn, and Zn)</p><p>More details on manure sampling can be found in Penn State Extension</p><p>Agronomy Facts #69 “Manure Sampling for Nutrient Management</p><p>Planning,” available at extension.psu.edu/plants/nutrient-management/</p><p>educational/manure-storage-and-handling/manure-sampling-for-</p><p>nutrient-management-planning.</p><p>One thorough reference for Ohio operations is the OSU Extension</p><p>Bulletin 604, Ohio Livestock Manure and Wastewater Management Guide:</p><p>agcrops.osu.edu/sites/agcrops/files/imce/fertility/bulletin_604.pdf.</p><p>http://extension.psu.edu/plants/nutrient-management/educational/manure-storage-and-handling/manure-sampling-for-nutrient-management-planning</p><p>http://extension.psu.edu/plants/nutrient-management/educational/manure-storage-and-handling/manure-sampling-for-nutrient-management-planning</p><p>http://extension.psu.edu/plants/nutrient-management/educational/manure-storage-and-handling/manure-sampling-for-nutrient-management-planning</p><p>http://agcrops.osu.edu/sites/agcrops/files/imce/fertility/bulletin_604.pdf</p><p>255</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>255</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>MANURE SPREADER CALIBRATION</p><p>Manure spreader calibration is an essential and valuable nutrient</p><p>management tool for maximizing the efficient use of available manure</p><p>nutrients. Planned manure application rates listed in nutrient management</p><p>plans must correlate with actual application rates. Calibrating the manure</p><p>spreader is the only way to know actual manure application rates. Manure</p><p>spreader calibration combined with soil test recommendations and manure</p><p>analysis results enable the determination of nutrient application rates that</p><p>meet crop nutrient needs and reduce the potential from environmental</p><p>impact from the manure nutrients.</p><p>There are two methods commonly used to calibrate a manure spreader.</p><p>The Swath or Load Area Method and the Tarp or Weight Area Method.</p><p>SWATH OR LOAD AREA METHOD</p><p>Liquid manure applicators used in pump-and-haul application systems are</p><p>best calibrated by the swath or load-area method, which involves land</p><p>applying a full load of manure and measuring the land area covered. If</p><p>possible, choose an area that is typical of the land where manure will be</p><p>spread. If appropriate, a relatively level area long enough for the load to</p><p>be applied in a single pass makes measurements and calculations simpler.</p><p>A rectangular field pattern should be used to make measuring easier.</p><p>The application rate of PTO-driven spreaders depends on ground speed.</p><p>Therefore, it is important to maintain a uniform ground speed throughout</p><p>the swath length. Ground-driven spreaders deliver reasonably uniform</p><p>application rates regardless of ground speed.</p><p>For liquid application equipment, application rates and patterns vary</p><p>depending on ground speed or PTO speed, gear box settings, gate</p><p>openings, operating pressures, spread widths, and overlaps. To change</p><p>the application rates, adjustments must be made in tractor/PTO speeds,</p><p>spreader output settings, or application management. The calibration</p><p>process should be followed for each change or combination of changes.</p><p>Several calibration passes may be necessary to determine the settings</p><p>required for the desired application rate.</p><p>To use this method the amount of manure in the loaded spreader must</p><p>be determined. This can be done by weighting the spreader—if scales</p><p>are available—or estimating the amount of manure in the spreader based</p><p>on the dimensions of the spreader, converting the volume of the manure</p><p>into gallons (7.48 gal/ft3) or use the manure density to convert to a weight.</p><p>To estimate manure density, fill a 5-gallon bucket with manure and weigh</p><p>the manure in the bucket and multiply this weight by 1.5 to get the weight</p><p>in lb/ft3.</p><p>Spread the load of manure and then measure the width of spread,</p><p>accounting for overlap at the edges and the distance traveled to spread the</p><p>load. Calculate the square footage covered and divide this by 43,560 ft2/A</p><p>256</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>256</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>then divide this area into the amount of manure that was in the spreader</p><p>as determined above. This will give the pounds or gallons of manure per</p><p>acre depending on whether the capacity of the spreader was determined</p><p>in pounds or gallons.</p><p>TARP OR WEIGHT AREA METHOD</p><p>Solid manure applicators are best calibrated by the tarp or weight-area</p><p>method, which involves measuring the amount of manure (weight) applied</p><p>over a small measured area (tarp) spread in the field. The application rate</p><p>is determined by dividing the amount (weight) of manure collected on the</p><p>tarp by the size of the collection area (tarp).</p><p>For solid application equipment, applications rates and patterns vary</p><p>depending on ground speed or PTO speed, gear box settings, gate</p><p>openings, operating pressures, spread widths, and overlaps. To change</p><p>the application rates, adjustments must be made in tractor/PTO speeds,</p><p>spreader output settings, or application management. The calibration</p><p>process should be followed for each change or combination of changes.</p><p>Several calibration passes may be necessary to determine the settings</p><p>required for the desired application rate.</p><p>To use this method you will need a tarp or heavy plastic sheet,</p><p>approximately 100 ft2 in size. Determine the actual square footage of the</p><p>tarp or plastic and weigh the empty tarp to get a tare. Position the tarp in</p><p>the field where</p><p>the manure can be spread. Place it far enough into the field</p><p>to allow enough distance to get the spreader in gear and the tractor up</p><p>to the desired speed. Avoid placing the tarp where the beginning or end</p><p>of the load is likely to fall. Secure each corner of the tarp with a tent peg</p><p>or long nail or some stones (if you use stones, remove the stones before</p><p>weighing). Spread the first pass of manure directly over the center of the</p><p>tarp. Operate the spreader at the speed normally driven when applying</p><p>manure. Note the details of the operating conditions (e.g., tractor gear,</p><p>throttle setting, PTO speed, tractor speed, spreader settings). Spread</p><p>two additional passes on opposite sides of the center of the tarp. Apply</p><p>these passes at the normal spreader overlap spacing. Ideally, this would</p><p>be done at least two or three times. Carefully gather up the tarp and the</p><p>manure and weigh it, subtracting the tare weight of the tarp. Divide the</p><p>square footage of the tarp by 43,560 ft2/A, then divide this area into the</p><p>amount of manure that was collected on the tarp. This will give the pounds</p><p>of manure per acre.</p><p>If a specific application rate is desired, adjustments to the spreader or</p><p>tractor speed can be made and the calibration process repeated until</p><p>the desired rate is achieved.</p><p>For more details on Manure Spreader Calibration see Penn State</p><p>Extension Agronomy Facts #68 “Manure Spreader Calibration,” available at</p><p>extension.psu.edu/plants/nutrient-management/educational/manure-</p><p>storage-and-handling/manure-spreader-calibration.</p><p>http://extension.psu.edu/plants/nutrient-management/educational/manure-storage-and-handling/manure-spreader-calibration</p><p>http://extension.psu.edu/plants/nutrient-management/educational/manure-storage-and-handling/manure-spreader-calibration</p><p>257</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>257</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>SOIL MANAGEMENT</p><p>DIAGNOSING SOIL COMPACTION WITH A</p><p>PENETROMETER (SOIL COMPACTION TESTER)</p><p>Soil compaction is the undesirable increase of soil density caused by</p><p>machinery or animals. Soil compaction threat is greatest when the soil is</p><p>moist; research shows that soil is most compactable at the plastic state</p><p>when it can be easily molded into a small ball. At higher moisture contents,</p><p>soil is highly sensitive to rutting and pugging which cause soil structure</p><p>destruction. The result of soil compaction is a reduction in large pore</p><p>spaces in the soil and an associated reduction in aeration and water</p><p>percolation. Soil compaction also results in reduced ability of roots to</p><p>penetrate the soil. Research has shown that root growth of most crops is</p><p>severely inhibited when penetration resistance exceeds 300 psi.</p><p>Image: Penn State figure courtesy of Dickey John</p><p>A penetrometer, or soil compaction tester, has a graded shaft and</p><p>separate reading scales for each tip.</p><p>Image: Penn State figure courtesy of Dickey John</p><p>A penetrometer usually comes with two points</p><p>(½ inch and ¾ inch diameter.)</p><p>258</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>258</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>Penetration resistance is measured with a penetrometer or soil compaction</p><p>tester. The penetrometer is useful to measure compaction at depths</p><p>greater than 3 inches. The penetrometer usually comes with two tips—a ½</p><p>inch diameter and a ¾ inch diameter tip. The larger diameter tip is suited</p><p>to soils with low penetration resistance. In most agricultural applications,</p><p>the ½-inch tip is used.</p><p>The dial on the penetrometer has two scales—one for each tip. Penetration</p><p>resistance varies with soil moisture content. To get a useful reading,</p><p>measure penetration resistance when the entire soil profile is at field</p><p>capacity (after free water has drained from the soil, which is typically 24-</p><p>48 hours after a soaking rain, depending on soil texture) to simulate the</p><p>ability of roots to penetrate the soil after it has been softened by rain or</p><p>irrigation. Push the penetrometer into the soil at a rate of about an inch per</p><p>second. The rod typically has indentations spaced 3 inches apart to help</p><p>you determine the rate and the depth of the readings. Note the depth at</p><p>which penetration resistance exceeds 300 psi, and the depth at which it</p><p>decreases below 300 psi (it may not decrease). A distinct layer with high</p><p>penetration resistance typically signifies a plow pan created by repeated</p><p>tillage at the same depth. If penetration resistance at depth is high and</p><p>does not decrease, you may have a case of subsoil compaction caused</p><p>by heavy machinery with axle loads exceeding 10 tons.</p><p>It is rare for animal foot traffic to cause subsoil compaction. It is still</p><p>important to dig the soil with a shovel and visually assess root penetration</p><p>and macropores. If there are many large pores in the soil created by</p><p>biological organisms such as earthworms or by shrink/swell action of clay</p><p>particles, roots may follow those pores despite high penetration resistance,</p><p>and water can drain through these pores in which case no further action</p><p>may be required.</p><p>If you conclude that remedial action is needed, it can include subsoiling.</p><p>Choose a subsoiler that does not invert but fractures the soil such that no</p><p>further tillage is needed. Set the depth just below the layer of compaction</p><p>(in case of a plow pan), or as deep as possible (if penetration resistance</p><p>remains high). Most subsoilers can operate to a depth of 18 inches and</p><p>no deeper. Operate the subsoiler when the soil is relatively dry but not</p><p>so dry that you pull up large chunks of soil. It typically takes at least 40</p><p>horse power to pull one subsoiler shank to an 18 inch depth through the</p><p>soil, so make sure your tractor has enough power for the job.</p><p>After you complete your subsoiling operation, plant a deep rooting crop</p><p>or cover crop. It is important to occupy the pore spaces with roots and</p><p>build soil structure before the soil collapses again. Also, make sure you</p><p>do not compact the soil again by staying off the soil when it is too wet, by</p><p>using low-inflation tires or tracks, and by limiting axle load to a maximum</p><p>of 10 tons.</p><p>259</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>259</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>EVALUATION OF SOIL HEALTH</p><p>Soil health (also called “soil quality”) is defined as “the continued capacity</p><p>of soil to function as a vital ecosystem that sustains plants, animals,</p><p>and humans” (from USDA-NRCS Soil Health Website). Soil health is the</p><p>combined outcome of soil physical, chemical, and biological properties.</p><p>University and commercial laboratories offer well-established evaluation</p><p>of chemical properties and recommendations to amend the soil for optimal</p><p>yields (see the chapter on soil fertility in this guide).</p><p>It is more challenging to evaluate the physical and biological health of the</p><p>soil. There are a number of soil health tests offered through laboratories</p><p>in the United States, but these tests are still under development. Each</p><p>test has its own pros and cons. For example, it is very challenging to take</p><p>a representative sample to a lab to evaluate infiltration capacity due to</p><p>high variability in the field and due to difficulties taking and sending in an</p><p>undisturbed sample. Therefore, field evaluation has its place, either on</p><p>its own or to complement the results of a lab analysis of soil health. Penn</p><p>State offers a Soil Quality Assessment Worksheet that can help assess</p><p>soil health. It is available from Penn State Extension here: extension.psu.</p><p>edu/pennsylvania-soil-quality-assessment-worksheet.</p><p>The first step is to gather information from the web-soil survey. This gives</p><p>you basic information about your soil, such as the soil series, slope, and</p><p>permeability, that is the result of soil forming factors beyond your control.</p><p>This information is important to determine a baseline and avoid unrealistic</p><p>expectations as to what can be done to improve soil health on your farm.</p><p>Next, the sheet asks you to enter management information such as crop</p><p>rotation, tillage, manure applications, yields, and observations that can</p><p>explain</p><p>with</p><p>limited kernel formation. Some ear</p><p>shoots carry either no ear or only</p><p>the short remnant of an ear. Often</p><p>silks are absent or limited. Severity</p><p>of symptoms differs among</p><p>hybrids. Corn plants with arrested</p><p>ears generally appear healthy, i.e.,</p><p>exhibited normal plant height and</p><p>color.</p><p>Causes: Applying a nonionic</p><p>surfactant (NIS) prior to tasseling</p><p>(VT growth stage) may result in</p><p>arrested ear development. Some</p><p>portion of the cob along with ovule</p><p>development at the tip end of the</p><p>ear, appears to prematurely cease shortly after a foliar NIS application.</p><p>The risk appears to be greatest from growth stages V12 to V14 (12 to 14</p><p>exposed leaf collars), one or two weeks prior to pollination.</p><p>EAR PINCHING (“BEER BOTTLE EARS”)</p><p>Symptoms: Kernel row</p><p>numbers may decrease by</p><p>half from bottom to top of</p><p>ear (for example, from 16</p><p>to 8 kernel rows per ear).</p><p>The ear length is usually</p><p>about normal.</p><p>Causes: Severe stress</p><p>during the 7- to 10-leaf</p><p>collar stages and late</p><p>application of sulfonylurea</p><p>herbicides.</p><p>19</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>19</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>BLUNT EAR SYNDROME (“BEER CAN EARS,”</p><p>“EAR STUNTING”)</p><p>Symptoms: Markedly reduced ear size and kernel numbers per row.</p><p>Husk length and kernel row number may be normal.</p><p>Causes: Unknown but is associated with low temperature stress</p><p>during early ear formation.</p><p>CHAFFY EARS</p><p>Symptoms: Lightweight, poorly</p><p>filled ears with shrunken kernels</p><p>and spaces between kernels.</p><p>Causes: Frost damage, premature</p><p>plant death from drought, foliar</p><p>disease, severe potassium</p><p>deficiency, or hail from the dough</p><p>through early dent stages.</p><p>20</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>20</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>DROUGHT-DAMAGED EARS (“NUBBIN EARS”)</p><p>Symptoms: Small misshaped ears with poor kernel set at ear tip.</p><p>Causes: Severe drought and other stresses, such as nitrogen</p><p>deficiency and high plant population.</p><p>21</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>21</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>KERNEL RED STREAK</p><p>Symptoms: Red streaks form on sides of kernels and extend over the</p><p>crown. Usually more common at ear tips, especially if the husks are</p><p>loose and kernels exposed.</p><p>Cause: Kernel red streak is caused by a toxin secreted during feeding</p><p>by the wheat curl mite.</p><p>Management: Severity of symptom expression varies among hybrids.</p><p>Kernel red streak is most common on yellow dent and least common on</p><p>white corn.</p><p>Photo: P. Thomison, OSU Extension</p><p>22</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>22</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>POOR, INCOMPLETE KERNEL SET</p><p>Symptoms: Poor,</p><p>reduced kernel</p><p>set. When severe,</p><p>ears have scattered</p><p>kernels or no</p><p>distinct kernel rows.</p><p>Causes: Poor</p><p>pollination due</p><p>to mistiming of</p><p>pollen shed and</p><p>silking caused by</p><p>drought and high</p><p>temperatures,</p><p>uneven crop</p><p>development,</p><p>insect feeding</p><p>and silk clipping,</p><p>and phosphorus</p><p>deficiency.</p><p>MULTIPLE EAR SYNDROME (“BOUQUET EARS”)</p><p>Symptoms: Multiple ears on</p><p>the same ear shank—sometimes</p><p>five or six ears form a “bouquet.”</p><p>Side ears may or may not be</p><p>fully developed.</p><p>Causes: Unknown but similar to</p><p>blunt ear syndrome.</p><p>23</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>23</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>TASSEL EARS</p><p>Symptoms: Combination</p><p>of tassel and ear in the same</p><p>structure.</p><p>Causes: Injury to growing point,</p><p>early season compaction and</p><p>saturated soil along field edges.</p><p>TIP DIEBACK</p><p>Symptoms: Poor tip fill or unfilled</p><p>ear tips and kernel abortion at</p><p>tip end of ear at blister and milk</p><p>stages. Affected kernels may be</p><p>dried up and are often light yellow.</p><p>Causes: Stress during early</p><p>kernel development, including</p><p>severe drought, heat, nitrogen</p><p>deficiency, foliar diseases and</p><p>cloudy weather.</p><p>24</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>24</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>ZIPPER EARS (“BANANA EARS”)</p><p>Symptoms: Partially to</p><p>completely missing kernel rows</p><p>on the underside of the ear</p><p>from kernel abortion or lack of</p><p>pollination. Ears often bend (like a</p><p>banana) due to differential kernel</p><p>abortion along the ear.</p><p>Causes: Often associated</p><p>with nitrogen deficiency, plant</p><p>population, severe drought stress,</p><p>or defoliation following pollination.</p><p>25</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>25</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>ABIOTIC STRESS IN CORN</p><p>SOIL CRUSTING AND LEAFING</p><p>OUT CORKSCREWS</p><p>Soil crusting and low temperature effects on emergence leading to</p><p>leafing out underground and abnormal “corkscrew” seedling growth.</p><p>Often associated with surface compaction and heavy rains following</p><p>planting. Prompt use of a rotary hoe or spiketooth harrow to break crust</p><p>may promote emergence.</p><p>FROST</p><p>Frost injury often more pronounced in low lying areas. Leaves initially</p><p>appear gray to whitish in color and water soaked. Severity of injury</p><p>related to location of growing point. If it's at or below- ground (before V6</p><p>stage), injury usually negligible.</p><p>26</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>26</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>ROOTLESS CORN LODGING (“FLOPPY CORN”)</p><p>Following wind storm. This condition is associated with poor secondary</p><p>(nodal) root development caused by dry soil, high temperatures, and</p><p>shallow plantings.</p><p>GREEN SNAP OR BRITTLE SNAP</p><p>Resulting from wind injury at V12-14 stage; associated with favorable</p><p>growing conditions and rapid plant growth. Hybrids exhibit varying</p><p>degrees of susceptibility to green snap.</p><p>27</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>27</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>INSECT SCOUTING CALENDAR FOR</p><p>CORN</p><p>P</p><p>es</p><p>t</p><p>A</p><p>pr</p><p>M</p><p>ay</p><p>Ju</p><p>ne</p><p>Ju</p><p>l</p><p>A</p><p>ug</p><p>S</p><p>ep</p><p>O</p><p>ct</p><p>Fl</p><p>ea</p><p>B</p><p>ee</p><p>tle</p><p>Se</p><p>ed</p><p>co</p><p>rn</p><p>M</p><p>ag</p><p>go</p><p>t</p><p>W</p><p>hi</p><p>te</p><p>G</p><p>ru</p><p>b</p><p>W</p><p>ire</p><p>w</p><p>or</p><p>m</p><p>C</p><p>ut</p><p>w</p><p>or</p><p>m</p><p>(i</p><p>nc</p><p>lu</p><p>di</p><p>ng</p><p>b</p><p>la</p><p>ck</p><p>)</p><p>Tr</p><p>ue</p><p>A</p><p>rm</p><p>yw</p><p>or</p><p>m</p><p>St</p><p>al</p><p>k</p><p>B</p><p>or</p><p>er</p><p>Sl</p><p>ug</p><p>s</p><p>C</p><p>or</p><p>n</p><p>Ro</p><p>ot</p><p>w</p><p>or</p><p>m</p><p>Eu</p><p>ro</p><p>pe</p><p>an</p><p>C</p><p>or</p><p>n</p><p>B</p><p>or</p><p>er</p><p>(1</p><p>st</p><p>)</p><p>C</p><p>or</p><p>n</p><p>Ro</p><p>ot</p><p>w</p><p>or</p><p>m</p><p>A</p><p>du</p><p>lt</p><p>W</p><p>es</p><p>te</p><p>rn</p><p>B</p><p>ea</p><p>n</p><p>C</p><p>ut</p><p>w</p><p>or</p><p>m</p><p>C</p><p>or</p><p>n</p><p>Le</p><p>af</p><p>A</p><p>ph</p><p>id</p><p>Eu</p><p>ro</p><p>pe</p><p>an</p><p>C</p><p>or</p><p>n</p><p>B</p><p>or</p><p>er</p><p>(2</p><p>nd</p><p>)</p><p>28</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>28</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>CORN PESTS</p><p>Pest Corn Stage Symptoms</p><p>Seed Maggot Seed No Emergence</p><p>Grub Seeds and Seedling</p><p>No Emergence or</p><p>Dead Early Whorl</p><p>Slug Seedlings Foliar injury</p><p>Black Cutworm Seedling to 6 Leaf</p><p>Below ground injury</p><p>and above ground</p><p>cutting</p><p>Stalk Borer Seedling to Early Whorl</p><p>Stalk bored above</p><p>ground</p><p>Armyworm Pre-Whorl to Whorl Foliar Injury</p><p>Note: Significant in no-till corn in grassy cover</p><p>Corn Borer</p><p>Early Whorl</p><p>to Harvest</p><p>Foliar shot holes,</p><p>stalk and ear</p><p>tunneling</p><p>Rootworm (lv) June and July</p><p>Root injury and</p><p>lodging</p><p>Note: Predominantly a problem on continuous corn but may be a</p><p>problem on first year corn.</p><p>Rootworm (Ad) July and Aug. Foliar and Silk Injury</p><p>Western Bean</p><p>Cutworm</p><p>July and Aug. Ear feeding</p><p>29</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>29</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>SEEDCORN MAGGOT</p><p>Identification and Incidence: Corn emergence failure due to</p><p>feeding by small, yellowish white, legless fly larvae (maggots) on</p><p>germinating seeds. Damage is likely to occur in fields that have had</p><p>green material, such as cover crops or weeds, incorporated into the</p><p>soil, and when cool and damp soil conditions delay emergence.</p><p>Sampling: Maggots may be detected by inspecting seed rows</p><p>exhibiting lack of emergence. Dig with a hand trowel around gaps and</p><p>look for damaged seed, white maggots or pupae (which resemble a</p><p>grain of brown rice).</p><p>Economic Threshold: No economic threshold exists for this insect.</p><p>High risk fields (see above) should be monitored and may need</p><p>preventative treatment.</p><p>Management Options: Seed maggot injury may be prevented</p><p>by use of seed treatment (not imidacloprid) or soil insecticide. For</p><p>more information, visit aginsects.osu.edu or extension.psu.edu/</p><p>publications/agrs-026.</p><p>Larva, Pupae, and Damage</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>http://extension.psu.edu/publications/agrs-026</p><p>30</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>30</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>WIREWORMS</p><p>Identification and Incidence: Seed or seedling stage may be</p><p>attacked by yellow-brown beetle larvae exhibiting a coarse skin</p><p>appearance. Injured seeds exhibit chewed cavities. Wireworm feeding</p><p>at base of corn seedling will kill growing point of</p><p>your soil health and what can be changed to improve it. Finally,</p><p>the sheet helps you rate physical and biological indicators of soil health.</p><p>The equipment you use is limited to a shovel and perhaps an infiltration</p><p>ring and some water to do an infiltration test. Farmers have found it useful</p><p>to follow soil health in their fields over time to determine if management</p><p>changes help improve it.</p><p>http://extension.psu.edu/pennsylvania-soil-quality-assessment-worksheet</p><p>http://extension.psu.edu/pennsylvania-soil-quality-assessment-worksheet</p><p>260</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>260</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>TEMPERATURE</p><p>DEVELOPMENT UNITS</p><p>There are three methods that are used to determine temperature</p><p>development units. Two methods, Degree Days (DD) and Heat Units</p><p>(HU), are used to help in determining insect development while the third</p><p>method, Growing Degree Days (GDD) is used in determining the stage</p><p>of plant development.</p><p>A brief description of each method and how it is computed is as follows:</p><p>1. Degree Days (DD) is used to predict the development of insects. It</p><p>assumes there are 12 hours of low temperature and 12 hours of high</p><p>temperature in a 24-hour period. The DD is calculated by adding</p><p>the low and high temperatures, dividing by 2 and subtracting a base</p><p>temperature at which the insect is active.</p><p>DD = Average temperature – Threshold</p><p>Ex: Max. temp. = 70; Min. temp. = 45; Threshold = 50</p><p>70 + 45</p><p>2</p><p>– 50 = 7.5 DD</p><p>In this example 7.5 degree days have accumulated.</p><p>2. Growing Degree Days (GDD) is used to predict physiological maturity</p><p>in hybrids and is a modification of Degree Days. GDD assumes that</p><p>some biological activity occurs even if the temperature is above 50</p><p>degrees Fahrenheit for part of a day, even if the average temperature</p><p>is below threshold.</p><p>Ex: Max. temp. = 65; Min. temp. = 40; Threshold = 50</p><p>65 + 50</p><p>2</p><p>– 50 = 7.5 GDD</p><p>GDD also assumes that maximum biological activity occurs at 86 degrees</p><p>Fahrenheit and plants do not grow faster above this temperature.</p><p>Ex: Max. temp. = 90; Min. temp. = 70; Threshold = 50</p><p>86 + 70</p><p>2</p><p>– 50 = 28 GDD</p><p>261</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>261</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>TEMPERATURE DEVELOPMENTAL</p><p>UNITS (CONT.)</p><p>3. Cosine Curve Method (CCM)—Heat Units (HU)</p><p>This method is used to predict insect development and accounts for the</p><p>fact that temperatures do not stay the same throughout the 24-hour period,</p><p>but follow a curve. A cosine curve is fitted to yesterday’s minimum and</p><p>today’s maximum and the temperature after each hour is computed. The</p><p>HU accumulations for a 24-hour period are summed and that gives the</p><p>number of HU for the day.</p><p>ESTIMATING SURFACE</p><p>RESIDUE COVER</p><p>The amount of crop residue left on the soil after a tillage or planting</p><p>operation is important for erosion control. There are several ways and</p><p>tools that can be used to measure crop residue. Following is a method</p><p>that can be used to estimate the percentage of soil surface covered by</p><p>crop residue after a tillage or planting operation.</p><p>1. Divide a 50-foot rope into 100 equal parts (6 inches apart) by tying</p><p>knots or attaching tape at each division. Stretch the rope diagonally</p><p>across the crop rows at a 45 degree angle.</p><p>2. Walk along the rope and count the number of times a piece of crop</p><p>residue intersects a knot or piece of tape. Be sure to look at the same</p><p>place on the knot or tape to maintain accuracy.</p><p>3. After walking the entire length of rope, total the number of times that</p><p>crop residue intersects a knot or piece of tape. This is equal to the</p><p>percentage of soil surface covered with crop residue. Example: if 35</p><p>knots or pieces of tape intersected a piece of crop residue, then 35</p><p>percent of the soil surface would be covered with crop residue.</p><p>4. Repeat this procedure in either three or five areas in the field and</p><p>average the numbers to obtain an average estimate of residue cover</p><p>in the field. Do not take measurements in turn row areas.</p><p>262</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>262</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>SOIL pH RECOMMENDED</p><p>FOR VARIOUS CROPS ON</p><p>VARIOUS SOILS</p><p>Crop</p><p>Mineral soils with subsoil pH</p><p>Organic soils</p><p>> pH 6 < pH 6</p><p>pH</p><p>Alfalfa 6.5 6.8 5.3</p><p>Other forage</p><p>legumes</p><p>6.0 6.8a 5.3</p><p>Corn 6.0 6.5 5.3</p><p>Soybeans 6.0 6.5 5.3</p><p>Small grains 6.0 6.5 5.3</p><p>Other crops 6.0 6.5 5.3</p><p>a Birdsfoot trefoil should be limed to pH 6.0.</p><p>263</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>263</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>OHIO LIME RECOMMENDATIONS</p><p>Tons of aglime (Effective Neutralizing Power (ENP) of 2000 lbs/ton) needed</p><p>to raise the soil pH to the desired pH level based on the Shoemaker-</p><p>McLean-Pratt (SMP) buffer pH and an incorporation depth of 8 inches. For</p><p>no-till application, the rate should be divided by 2 (soil samples should</p><p>only be collected to a depth of 4 inches).</p><p>Buffer</p><p>pH*</p><p>Desired pH levels</p><p>Mineral soils Organic Soils</p><p>6.8 6.5 6.0 Soil pH 5.3</p><p>tons agricultural limestone/</p><p>acre tons/acre</p><p>6.8 0.9 0.8 0.7 5.2 0.0</p><p>6.7 1.6 1.4 1.1 5.1 0.5</p><p>6.6 2.2 2.0 1.6 5.0 0.8</p><p>6.5 2.9 2.5 2.0 4.9 1.3</p><p>6.4 3.6 3.1 2.5 4.8 1.7</p><p>6.3 4.2 3.6 3.0 4.7 2.1</p><p>6.2 4.9 4.2 3.4 4.6 2.5</p><p>6.1 5.6 4.7 3.9 4.5 2.9</p><p>6.0 6.2 5.3 4.4 4.4 3.3</p><p>5.9 6.9 5.9 4.7</p><p>*Lime test index (LTI), which may be reported in place of buffer pH, is buffer pH</p><p>times 10.</p><p>Visit Ohioline for Ohio Lime Recommendations: ohioline.osu.edu/factsheet/AGF-</p><p>505-07.</p><p>For Pennsylvania lime recommendations: agsci.psu.edu/aasl/soil-testing/soil-</p><p>fertility-testing/handbooks/agronomic/tables/lime-recommendations.</p><p>http://ohioline.osu.edu/factsheet/AGF-505-07</p><p>http://ohioline.osu.edu/factsheet/AGF-505-07</p><p>http://agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks/agronomic/tables/lime-recommendations</p><p>http://agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks/agronomic/tables/lime-recommendations</p><p>264</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>264</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>SOIL TESTING P ISSUES</p><p>A soil nutrient test estimates the amount of crop-available nutrient such</p><p>as phosphorus (P) in a soil with a chemical solution or extractant.</p><p>There are a number of soil tests with different extractants available,</p><p>and some tests are more appropriate for some regions of the country,</p><p>depending on predominant soil types in that region. It is important</p><p>that recommended soil tests are used. This is especially important for</p><p>phosphorus since there are environmental regulations that use the</p><p>recommended soil tests. Interpretations and recommendations are specific</p><p>to the test used and cannot be used interchangeably without conversions.</p><p>Also, the form of the nutrient reported and the units can vary. For example,</p><p>some labs report the elemental form of the nutrient (e.g., P) where others</p><p>report the oxide form (e.g., P2O5 ).</p><p>Units vary with some labs reporting in ppm and others in pounds per</p><p>acre. Below are simple mathematical conversions that can be used to</p><p>change soil test results from labs using the recommended procedures</p><p>but reporting results in different forms and units. (Important note: This only</p><p>applies to the soil test level. The recommendations are always given as</p><p>pounds of P2O5 and K2O per acre so no conversions are necessary for</p><p>the recommendations.</p><p>lbs P2O5/A ÷ 4.6 = ppm P</p><p>ppm P2O5 ÷ 2.3 = ppm P</p><p>lbs P/A ÷ 2 = ppm P</p><p>lbs K2O/A ÷ 2.4 = ppm K</p><p>ppm K2O ÷ 1.2 = ppm K</p><p>lbs K/A ÷ 2 = ppm K</p><p>lbs MgO/A ÷ 3.2 = ppm Mg</p><p>ppm MgO ÷ 1.6 = ppm Mg</p><p>lbs Mg/A ÷ 2 = ppm Mg</p><p>In Pennsylvania, the Mehlich 3 (M3) test is recommended for P, K, Ca, and</p><p>Mg. Recommendations for Pennsylvania based on the Mehlich 3 test in</p><p>ppm elemental form can be found at agsci.psu.edu/aasl/soil-testing/</p><p>soil-fertility-testing/handbooks.</p><p>Going forward, it is intended that Ohio soil nutrient recommendations</p><p>will be based on the Mehlich-3 test for both phosphorus and potassium</p><p>also. Trial work over the past several years was used to correlate yield</p><p>with these soil test results. Results to date are approximate and will be</p><p>published in final form as the new</p><p>Tri-State Fertilizer Recommendations</p><p>in conjunction with Michigan State University, Ohio State University, and</p><p>http://agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks</p><p>http://agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks</p><p>265</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>265</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>Purdue University. For more information, please see soilfertility.osu.edu</p><p>and agcrops.osu.edu/FertilityResources.</p><p>For additional information on comparing Bray P-1, as used in past Tri-State</p><p>Recommendations, to Mehlich 3 ICP test results, see the Soil Fertility</p><p>fact sheet, “Understanding Soil Tests for Plant-Available Phosphorus” at</p><p>agcrops.osu.edu/sites/agcrops/files/imce/fertility/Soil_Tests.pdf.</p><p>OPTIMUM NUTRIENT LEVELS FOR</p><p>AGRONOMIC CROPS</p><p>Optimum levels used to interpret the Mehlich 3 soil test for agronomic</p><p>crops in Pennsylvania—this is very similar for Ohio and can be used there</p><p>as well. Sample and retest every three to four years and compare results</p><p>to keep from getting too far off track.</p><p>Soil Test Optimum range Comments</p><p>pH 6.0-7.0 A pH of 6.0-6.5 is considered</p><p>adequate for most agronomic</p><p>crops; however, 6.5-7.0 is</p><p>recommended for alfalfa and</p><p>barley.</p><p>Phosphorus (P) 30-50 ppm All agronomic crops</p><p>Potassium (K) 100-150 ppm Grain crops</p><p>100-200 ppm Forage crops</p><p>Magnesium (Mg) 120-180 ppm Grass forage crops</p><p>60-120 ppm Other agronomic crops</p><p>http://soilfertility.osu.edu</p><p>http://agcrops.osu.edu/FertilityResources</p><p>http://agcrops.osu.edu/sites/agcrops/files/imce/fertility/Soil_Tests.pdf</p><p>266</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>266</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>CROP AND SOIL CONDITIONS</p><p>WHERE SECONDARY AND</p><p>MICRONUTRIENT DEFICIENCIES</p><p>MAY OCCUR</p><p>Micronutrient Soil Crop</p><p>Boron (B)</p><p>Sandy soils or highly</p><p>weathered soils low in</p><p>organic matter</p><p>Alfalfa and clover</p><p>Calcium (Ca) Very low pH soils Alfalfa</p><p>Copper (Cu)</p><p>Acid peats or mucks and</p><p>black sands</p><p>Wheat, oats and</p><p>corn</p><p>Iron (Fe)</p><p>High pH, wet poorly aerated</p><p>soil, cool temperature</p><p>Soybeans, navy</p><p>beans, millet,</p><p>milo</p><p>Magnesium (Mg) Low pH, high K, sandy soils Corn</p><p>Manganese (Mn)</p><p>High pH, high organic</p><p>matter</p><p>Soybeans, navy</p><p>beans</p><p>Molybdenum (Mo) Acid prairie soils</p><p>Soybeans and</p><p>alfalfa</p><p>Sulfur (S)</p><p>Low organic matter, sandy,</p><p>cold, wet soils</p><p>Alfalfa</p><p>Zinc (Zn)</p><p>Peats, mucks, and mineral</p><p>soils with pH > 6.5, high P,</p><p>heavily manured</p><p>Soybeans and</p><p>alfalfa</p><p>267</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>267</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>MICRONUTRIENT SOURCES</p><p>COMMONLY USED FOR</p><p>CORRECTING MICRONUTRIENT</p><p>DEFICIENCIES IN PLANTS</p><p>Micronutrient Common fertilizer sources</p><p>Boron (B)</p><p>Sodium tetraborate (14 to 20% B)</p><p>Solubor® (20% B)</p><p>Liquid boron (10%)</p><p>Copper (Cu)</p><p>Copper sulfate (13 to 35% Cu)</p><p>Copper oxide1 (75 to 89% Cu)</p><p>Manganese (Mn)</p><p>Manganese sulfate (23 to 28% Mn)</p><p>Manganese oxysulfates (variable % Mn)</p><p>Zinc (Zn)</p><p>Zinc sulfate (23 to 36% Zn)</p><p>Zinc-ammonia complex (10% Zn)</p><p>Zinc oxysulfates (variable % Zn)</p><p>Zinc oxide1 (50 to 80% Zn)</p><p>Zinc chelate (9 to 14% Zn)</p><p>® Registered trade name of U.S. Borax.</p><p>1 Granular oxides are not effective sources of micronutrients.</p><p>268</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>268</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>LENGTH OF ROW EQUAL TO</p><p>1/1000TH ACRE</p><p>Measuring the number of plants in an acre is done sometime during the</p><p>growing season. A simple method to use is by counting the number of</p><p>plants in 1/1000th of an acre. This is done by measuring along the row the</p><p>distance needed to equal 1/1000th of an acre (based on row width). The</p><p>number of plants are counted in this measured distance. After doing this</p><p>in at three separate sections of the field, the average of these samples is</p><p>calculated and multiplied by 1000. This represents the number of plants</p><p>per acre.</p><p>Row width Length of single row to equal 1/1000th of an acre</p><p>Inches Feet Inches</p><p>6 87 1</p><p>7 74 8</p><p>8 65 4</p><p>10 52 3</p><p>15 34 10</p><p>20 26 2</p><p>28 18 8</p><p>30 17 5</p><p>32 16 4</p><p>36 14 6</p><p>38 13 9</p><p>40 13 1</p><p>269</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>269</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>AREA AND VOLUME CALCULATIONS</p><p>Area of a</p><p>circle</p><p>=</p><p>radius squared X 3.1416</p><p>or diameter squared X</p><p>0.7854</p><p>Area of a</p><p>rectangle or</p><p>square</p><p>= length X width</p><p>Area of a</p><p>triangle</p><p>= base X height divided by 2</p><p>Volume of</p><p>a cube or</p><p>rectangular</p><p>box</p><p>= length X width X height</p><p>Volume of a</p><p>cylinder</p><p>=</p><p>radius X 3.1416 X length of</p><p>cylinder</p><p>Volume of a</p><p>cone</p><p>=</p><p>radius squared X 1.0472 X</p><p>height</p><p>270</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>270</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>CONVERSION FACTORS</p><p>Acres X 0.405 = Hectares</p><p>Acres X 43560 = Sq Feet</p><p>Bushels X 1.244 = Cubic feet</p><p>Bushels X 4 = Pecks</p><p>CaCO3 X 0.40 = Calcium(Ca)</p><p>CaCO3 X 0.84 = MgCO3</p><p>Calcium (Ca) X 2.50 = CaCO3</p><p>Centimeters X 0.3937 = Inches</p><p>Centimeters X 0.01 = Meters</p><p>Centimeters X 10 = Millimeters</p><p>Cord (4' x 4' x 8') X 8 = Cord feet</p><p>Cubic feet X 1,728 = Cubic inches</p><p>Cubic feet X 0.03704 = Cubic yards</p><p>Cubic feet X 7.4805 = Gallons</p><p>Cubic feet X 0.84 = Bushels</p><p>Cubic inches X 16.39 = Cubic Centimeters</p><p>Cubic meters X 35.31 = Cubic feet</p><p>Degree Celsius (+17.98) X 1.8 = Fahrenheit</p><p>Fahrenheit (-32) X 0.5555 = Celsius</p><p>Feet X 30.48 = Centimeters</p><p>Feet X 12 = Inches</p><p>Feet X 0.3048 = Meters</p><p>Feet X 0.33333 = Yards</p><p>Ft / minute X 0.01667 = Ft / second</p><p>Ft / minute X 0.01136 = Miles / hour</p><p>Fl ounce X 1.805 = Cubic inches</p><p>Gallons X 269 = Cubic in. (dry)</p><p>Gallons X 231 = Cubic in. (liq)</p><p>Gallons X 3,785 = Cubic Centimeter</p><p>Gallons X 0.1337 = Cubic feet</p><p>Gallons X 3.785 = Liters</p><p>Gallons X 128 = Ounces (liquid)</p><p>Gallons X 8 = Pints (liquid)</p><p>Gallons X 4 = Quarts (liquid)</p><p>Gallons of water X 8.3453 = Pounds water</p><p>Grams X 0.001 = Kilograms</p><p>Grams X 1,000 = Milligrams</p><p>Grams X 0.0353 = Ounces</p><p>Grams per liter X 1,000 = Parts / million</p><p>271</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>271</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>CONVERSION FACTORS</p><p>Hectares X 2.471 = Acres</p><p>Inches X 2.54 = Centimeters</p><p>Kilograms (kg) X 1000 = Grams (g)</p><p>Kilograms X 2.205 = Pounds</p><p>Kg/hectare X 0.8929 = Pounds/acre</p><p>Kilometers X 3,281 = Feet</p><p>Kilometers X 1,000 = Meters</p><p>Kilometers X 0.6214 = Miles</p><p>Knot X 6,086 = Feet</p><p>K2O X 0.83 = K (elemental)</p><p>Liters X 1,000 = Milliliters</p><p>Liters X 1,000 = Cubic Centimeters</p><p>Liters X 0.0353 = Cubic feet</p><p>Liters X 0.2642 = Gallons</p><p>Magnesium (Mg) X 3.48 = MgCO3</p><p>Meters X 100 = Centimeters</p><p>Meters X 39.37 = Inches</p><p>Meters X 0.001 = Kilometers</p><p>Meters X 1,000 = Millimeters</p><p>Meters X 1.094 = Yards</p><p>MgCO3 X 0.29 = Magnesium (Mg)</p><p>MgCO3 X 1.18 = CaCO3</p><p>Miles X 5,280 = Feet</p><p>Miles X 1.6909 = Kilometers</p><p>Miles per hour X 88 = Feet / minute</p><p>Miles per hour X 1.467 = Feet / second</p><p>Miles per minute X 88 = Feet / second</p><p>Milliliter X 0.034 = Fluid ounces</p><p>Ounces (dry) X 28.349 = Grams</p><p>Ounces (liquid) X 0.00781 = Gallons</p><p>Ounces (liquid) X 29.573 = Cubic centimeters</p><p>Ounces (liquid) X 0.03125 = Quarts (liquid)</p><p>P2O5 X 0.44 = P (elemental)</p><p>P (elemental) X 2.292 = P2O5</p><p>Parts / million X 2 = lbs/acre</p><p>Parts / million X 0.001 = Grams / liter</p><p>Parts / million X 0.0001 = Percent</p><p>Parts / million X 1 = Milligrams/Kg</p><p>Parts / million X 1 = Milligrams/liter</p><p>272</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>272</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>CONVERSION FACTORS</p><p>Pecks X 0.25 = Bushels</p><p>Pints (dry) X 33.6003 = Cubic inches</p><p>Pints (dry) X 0.5 = Quarts (dry)</p><p>Pints (liquid) X 28.875 = Cubic inches</p><p>Pints (liquid) X 0.125 = Gallons</p><p>Pints (liquid) X 0.4732 = Liters</p><p>Pints (liquid) X 16 = Ounces (liquid)</p><p>Pints (liquid) X 0.5 = Quarts (liquid)</p><p>Potash (K2O) X 0.83 = Potassium (K)</p><p>Potassium (K) X 1.20 = Potash (K2O)</p><p>Pounds X 453.592 = Grams</p><p>Pounds X 16 = Ounces</p><p>Pounds X 0.45359 = Kilograms (Kg)</p><p>Pounds water X 0.01602 = Cubic feet</p><p>Pounds water X 0.1198 = Gallons</p><p>Pounds / acre X 1.12 = Kg / hectare</p><p>Quarts X 946 = Milliliters</p><p>Quarts (dry) X 67.20 = Cubic inches</p><p>Quarts (liquid) X 0.9463 = Liters</p><p>Quarts (liquid) X 32 = Ounces (liquid)</p><p>Rods X 16.5 = Feet</p><p>Square feet X 0.000024 = Acres</p><p>Square meters X 0.0001 = Hectares (ha)</p><p>Square miles X 640 = Acres</p><p>Ton X 907.1849 = Kilograms</p><p>Ton (long) X 2,240 = Pounds</p><p>Ton (short) X 2,000 = Pounds</p><p>U.S.</p><p>dry quart X 1.101 = Liters</p><p>U.S. gallon X 3.785 = Liters</p><p>273</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>273</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>FIELD CROP</p><p>EXTENSION SPECIALISTS</p><p>Department State Specialization Phone</p><p>Application Technology</p><p>Erdal Ozkan</p><p>ozkan.2@osu.edu</p><p>OH</p><p>Pesticide</p><p>Application</p><p>Technology</p><p>614-292-3006</p><p>Crop Management</p><p>Laura E. Lindsey</p><p>lindsey.233@osu.edu</p><p>OH</p><p>Soybeans,</p><p>Small Grains</p><p>Management</p><p>614-292-9080</p><p>R. Mark Sulc</p><p>sulc.2@osu.edu</p><p>OH</p><p>Forage</p><p>Management</p><p>614-292-9084</p><p>Peter R. Thomison</p><p>thomison.1@osu.edu</p><p>OH</p><p>Corn Cropping</p><p>Systems</p><p>614-292-2373</p><p>Jessica Williamson</p><p>jaw67@psu.edu</p><p>PA</p><p>Forage Crops,</p><p>Grazing</p><p>814-865-9552</p><p>Disease Management</p><p>Alyssa Collins</p><p>aac18@psu.edu</p><p>PA Field Crop Disease 717-653-4728</p><p>Anne E. Dorrance</p><p>dorrance.1@osu.edu</p><p>OH Field Crop Disease 330-202-3560</p><p>Paul Esker</p><p>pde6@psu.edu</p><p>PA Field Crop Disease 814-865-0680</p><p>Pierce A. Paul</p><p>paul.661@osu.edu</p><p>OH Field Crop Disease 330-263-3842</p><p>Insect Management</p><p>Andrew (Andy) P.</p><p>Michel</p><p>michel.70@osu.edu</p><p>OH</p><p>Field Crops Insect</p><p>Management</p><p>330-263-3730</p><p>Kelley Tilmon</p><p>tilmon.1@osu.edu</p><p>OH</p><p>Field Crops Insect</p><p>Management</p><p>330-202-3529</p><p>John Tooker</p><p>tooker@psu.edu</p><p>PA</p><p>Field Crops Insect</p><p>Management</p><p>814-865-7028</p><p>Soil Fertility</p><p>Steven W. Culman</p><p>culman.2@osu.edu</p><p>OH</p><p>Nutrient</p><p>Management</p><p>330-263-3785</p><p>Charles White</p><p>cmw29@psu.edu</p><p>PA</p><p>Nutrient</p><p>Management</p><p>814-863-1016</p><p>274</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>274</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>Department State Specialization Phone</p><p>Soil Management</p><p>Sjoerd Duiker</p><p>swd10@psu.edu</p><p>PA Soil Management 814-863-7637</p><p>Weed Management</p><p>Dwight Lingenfelter</p><p>dwight@psu.edu</p><p>PA Weed Science 814-865-2242</p><p>Mark M. Loux</p><p>loux.1@osu.edu</p><p>OH Weed Science 614-292-9081</p><p>John Wallace</p><p>jmw309@psu.edu</p><p>PA Weed Science 814-863-1014</p><p>Extension Field</p><p>Specialists,</p><p>Agronomic Systems</p><p>State Area Phone</p><p>Elizabeth M. Hawkins</p><p>hawkins.201@osu.edu</p><p>OH</p><p>Precision Ag, Data</p><p>management</p><p>937-382-0901</p><p>Greg A. LaBarge</p><p>labarge.1@osu.edu</p><p>OH</p><p>Soil fertility, Water</p><p>quality</p><p>740-852-0975</p><p>Harold D. Watters</p><p>watters.35@osu.edu</p><p>OH</p><p>Crop production,</p><p>Pest management,</p><p>Alternative crops</p><p>937-599-4227</p><p>275</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>275</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>EXTENSION EDUCATORS</p><p>To find an office or for more information: extension.osu.edu/lao</p><p>COUNTY ANR EDUCATORS PLUS</p><p>PROGRAM COORDINATORS</p><p>FIRST</p><p>NAME LAST NAME TITLE COUNTY PRIMARY</p><p>PHONE E-MAIL</p><p>David Dugan Ext Educ,</p><p>ANR</p><p>Adams 937-544-2339 dugan.46@osu.</p><p>edu</p><p>VACANT VACANT Ext Educ,</p><p>ANR</p><p>Allen 419-879-9108 VACANT</p><p>VACANT VACANT Ext Educ,</p><p>ANR</p><p>Ashland 419-281-8242  VACANT</p><p>Andrew Holden Ext Educ,</p><p>ANR</p><p>Ashtabula 440-576-9008 holden.155@osu.</p><p>edu</p><p>Ed Brown Ext Educ,</p><p>ANR</p><p>Athens 740-593-8555 brown.6000@</p><p>osu.edu</p><p>Jeff Stachler Ext Educ,</p><p>ANR</p><p>Auglaize 419-739-6580 stachler.1@osu.</p><p>edu</p><p>Dan Lima Ext Educ,</p><p>ANR</p><p>Belmont 740-695-1455 lima.19@osu.edu</p><p>James Morris Ext Educ,</p><p>ANR</p><p>Brown 937-378-6716 morris.1677@osu.</p><p>edu</p><p>VACANT VACANT Ext Educ,</p><p>ANR</p><p>Butler 513-887-3722 VACANT</p><p>Sandra Smith Ext Educ,</p><p>ANR</p><p>Carroll 330-627-4310 smith.10015@</p><p>osu.edu</p><p>Amanda Douridas Ext Educ,</p><p>ANR</p><p>Champaign 937-484-1526 douridas.9@osu.</p><p>edu</p><p>Pam Bennett Ext Educ,</p><p>ANR</p><p>Clark 937-521-3860 bennett.27@osu.</p><p>edu</p><p>Nanette</p><p>“Gigi”</p><p>Neal Ext Educ,</p><p>ANR</p><p>Clermont 513-732-7070 neal.331@osu.</p><p>edu</p><p>Tony Nye Ext Educ,</p><p>ANR</p><p>Clinton 937-382-0901 nye.1@osu.edu</p><p>VACANT VACANT Ext Educ,</p><p>ANR</p><p>Columbiana 330-424-7291 VACANT</p><p>David Marrison Ext Educ,</p><p>ANR</p><p>Coshocton 740-622-2265 marrison.2@osu.</p><p>edu</p><p>Jason Hartschuh Ext Educ,</p><p>ANR</p><p>Crawford 419-562-8731 hartschuh.11@</p><p>osu.edu</p><p>Maggie Fitzpatrick Ext Educ,</p><p>ANR</p><p>Cuyahoga 216-429-8200 fitzpatrick.255@</p><p>osu.edu</p><p>Sam Custer Ext Educ,</p><p>ANR</p><p>Darke 937-548-5215 custer.2@osu.</p><p>edu</p><p>Bruce Clevenger Ext Educ,</p><p>ANR</p><p>Defiance 419-782-4771 clevenger.10@</p><p>osu.edu</p><p>Rob Leeds Ext Educ,</p><p>ANR</p><p>Delaware 740-833-2030 leeds.2@osu.edu</p><p>Jacci Smith Ext Educ,</p><p>ANR</p><p>Delaware 740-833-2030 smith.11005@</p><p>osu.edu</p><p>276</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>276</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>COUNTY ANR EDUCATORS PLUS</p><p>PROGRAM COORDINATORS</p><p>FIRST</p><p>NAME LAST NAME TITLE COUNTY PRIMARY</p><p>PHONE E-MAIL</p><p>Tim Malinich Ext Educ,</p><p>ANR</p><p>Erie 419-627-7631 malinich.1@osu.</p><p>edu</p><p>Jerry Iles Ext Educ,</p><p>ANR</p><p>Fairfield 740-652-7260 iles.9@osu.edu</p><p>Ken Ford Ext Educ,</p><p>ANR</p><p>Fayette 740-335-1150 ford.70@osu.edu</p><p>Mike Hogan Ext Educ,</p><p>ANR</p><p>Franklin 614-866-6900,</p><p>Ext 206</p><p>hogan.1@osu.edu</p><p>Tim McDermott Ext Educ,</p><p>ANR</p><p>Franklin 614-866-6900,</p><p>Ext 220</p><p>mcdermott.15@</p><p>osu.edu</p><p>Eric Richer Ext Educ,</p><p>ANR</p><p>Fulton 419-337-9210 richer.5@osu.edu</p><p>Jeff Moore Ext Educ,</p><p>ANR</p><p>Gallia 740-446-7007 moore.3036@</p><p>osu.edu</p><p>Erik Draper Ext Educ,</p><p>ANR</p><p>Geauga 440-834-4656 draper.15@osu.</p><p>edu</p><p>Trevor Corboy Ext Educ,</p><p>ANR</p><p>Greene 937-372-9971 corboy.3@osu.</p><p>edu</p><p>Clif Little Ext Educ,</p><p>ANR</p><p>Guernsey 740-489-5300 little.16@osu.edu</p><p>Joe Boggs Ext Educ,</p><p>ANR</p><p>Hamilton 513-946-8989 boggs.47@osu.</p><p>edu</p><p>Ed Lentz Ext Educ,</p><p>ANR</p><p>Hancock 419-422-3851 lentz.38@osu.</p><p>edu</p><p>Mark Badertscher Ext Educ,</p><p>ANR</p><p>Hardin 419-674-2297 badertscher.4@</p><p>osu.edu</p><p>Erika Lyon Ext Educ,</p><p>ANR</p><p>Harrison 740-942-8823 lyon.194@osu.</p><p>edu</p><p>Garth Ruff Ext Educ,</p><p>ANR</p><p>Henry 419-592-0806 ruff.72@osu.edu</p><p>Brooke Beam Ext Educ,</p><p>ANR</p><p>Highland 937-393-1918 beam.49@osu.</p><p>edu</p><p>VACANT VACANT Ext Educ,</p><p>ANR</p><p>Hocking 740-385-3222 VACANT</p><p>Gary Graham Ext Educ,</p><p>ANR</p><p>Holmes 330-674-3015 graham.124@osu.</p><p>edu</p><p>Mike Gastier Ext Educ,</p><p>ANR</p><p>Huron 419-668-8219 gastier.3@osu.</p><p>edu</p><p>VACANT VACANT Ext Educ,</p><p>ANR</p><p>Jackson 740-286-5044 VACANT</p><p>Erika Lyon Ext Educ,</p><p>ANR</p><p>Jefferson 740-264-2212 lyon.194@osu.</p><p>edu</p><p>John Barker, III Ext Educ,</p><p>ANR</p><p>Knox 740-397-0401 barker.41@osu.</p><p>edu</p><p>Sabrina Schirtzinger Ext Educ,</p><p>ANR</p><p>Knox 740-397-0401 schirtzinger.55@</p><p>osu.edu</p><p>Thomas deHaas Ext Educ,</p><p>ANR</p><p>Lake 440-350-2582 dehaas.2@osu.</p><p>edu</p><p>277</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>277</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>COUNTY ANR EDUCATORS PLUS</p><p>PROGRAM COORDINATORS</p><p>FIRST</p><p>NAME LAST NAME TITLE COUNTY PRIMARY</p><p>PHONE E-MAIL</p><p>VACANT VACANT Ext Educ,</p><p>ANR</p><p>Lawrence 740-533-4322 VACANT</p><p>Dean Kreager Ext Educ,</p><p>ANR</p><p>Licking 740-670-5315 kreager.5@osu.</p><p>edu</p><p>VACANT VACANT Ext Educ,</p><p>ANR</p><p>Logan 937-599-4227 VACANT</p><p>Ann Chanon Ext Educ,</p><p>ANR</p><p>Lorain 440-326-5851 chanon.1@osu.</p><p>edu</p><p>Amy Stone Ext Educ,</p><p>ANR</p><p>Lucas 419-213-4254 stone.91@osu.</p><p>edu</p><p>Mary Griffith Ext Educ,</p><p>ANR</p><p>Madison 740-852-0975 griffith.483@osu.</p><p>edu</p><p>Eric Barrett Ext Educ,</p><p>ANR</p><p>Mahoning 330-533-5538 barrett.90@osu.</p><p>edu</p><p>Tim Barnes Ext Educ,</p><p>ANR</p><p>Marion 740-223-4040   barnes.821@osu.</p><p>edu</p><p>Ashley Kulhanek Ext Educ,</p><p>ANR</p><p>Medina 330-725-4911 kulhanek.5@osu.</p><p>edu</p><p>Kevin Fletcher Ext Educ,</p><p>ANR</p><p>Meigs 740-992-4718 fletcher.204@</p><p>osu.edu</p><p>Dennis Riethman Ext Educ,</p><p>ANR</p><p>Mercer 419-586-2179 riethman.24@</p><p>osu.edu</p><p>Amanda Bennett Ext Educ,</p><p>ANR</p><p>Miami 937-440-3945 bennett.709@</p><p>osu.edu</p><p>Mark Landefeld Ext Educ,</p><p>ANR</p><p>Monroe 740-472-0810 landefeld.6@osu.</p><p>edu</p><p>Suzanne Mills-Wasniak Ext Educ,</p><p>ANR</p><p>Montgomery 937-224-9654 mills-wasniak.1@</p><p>osu.edu</p><p>Chris Penrose Ext Educ,</p><p>ANR</p><p>Morgan 740-962-4854 penrose.1@osu.</p><p>edu</p><p>Carri Jagger Ext Educ,</p><p>ANR</p><p>Morrow 419-947-1070 jagger.6@osu.</p><p>edu</p><p>Clifton Martin Ext Educ,</p><p>ANR</p><p>Muskingum 740-454-0144 martin.2422@</p><p>osu.edu</p><p>Christine Gelley Ext Educ,</p><p>ANR</p><p>Noble 740-732-5681 gelley.2@osu.</p><p>edu</p><p>VACANT VACANT Ext Educ,</p><p>ANR</p><p>Ottawa 419-898-3631  VACANT</p><p>Sarah Noggle Ext Educ,</p><p>ANR</p><p>Paulding 419-399-8225 noggle.17@osu.</p><p>edu</p><p>Ted Wiseman Ext Educ,</p><p>ANR</p><p>Perry 740-743-1602 wiseman.15@osu.</p><p>edu</p><p>Mike Estadt Ext Educ,</p><p>ANR</p><p>Pickaway 740-474-7534 estadt.3@osu.</p><p>edu</p><p>Jeff Fisher Ext Educ,</p><p>ANR</p><p>Pike 740-289-4837 fisher.7@osu.edu</p><p>Robin Christensen Ext Educ,</p><p>ANR</p><p>Portage 330-296-6432 christensen.227@</p><p>osu.edu</p><p>278</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>278</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>COUNTY ANR EDUCATORS PLUS</p><p>PROGRAM COORDINATORS</p><p>FIRST</p><p>NAME LAST NAME TITLE COUNTY PRIMARY</p><p>PHONE E-MAIL</p><p>VACANT VACANT Ext Educ,</p><p>ANR</p><p>Preble 937-456-8174  VACANT</p><p>Beth Scheckelhoff Ext Educ,</p><p>ANR</p><p>Putnam 419-523-6294 scheckelhoff.11@</p><p>osu.edu</p><p>VACANT VACANT Ext Educ,</p><p>ANR</p><p>Richland 419-747-8755 VACANT</p><p>Chris</p><p>Bruynis Ext Educ,</p><p>ANR</p><p>Ross 740-702-3200 bruynis.1@osu.</p><p>edu</p><p>Allen Gahler Ext Educ,</p><p>ANR</p><p>Sandusky 419-334-6340 gahler.2@osu.</p><p>edu</p><p>Brad Bergefurd Ext Educ,</p><p>ANR</p><p>Scioto 740-354-7879 bergefurd.1@osu.</p><p>edu</p><p>Hallie Williams Ext Educ,</p><p>ANR</p><p>Seneca 419-447-9722   williams.6386@</p><p>osu.edu</p><p>Debbie Brown Ext Educ,</p><p>ANR</p><p>Shelby 937-498-7239 brown.1522@</p><p>osu.edu</p><p>Heather Neikirk Ext Educ,</p><p>ANR</p><p>Stark 330-830-7700 neikirk.2@osu.</p><p>edu</p><p>Jaqueline Kowalski Ext Educ,</p><p>ANR</p><p>Summit 330-928-4769 kowalski.124@</p><p>osu.edu</p><p>Lee Beers Ext Educ,</p><p>ANR</p><p>Trumbull 330-638-6783 beers.66@osu.</p><p>edu</p><p>Chris Zoller Ext Educ,</p><p>ANR</p><p>Tuscarawas 330-339-2337 zoller.1@osu.edu</p><p>Wayne Dellinger Ext Educ,</p><p>ANR</p><p>Union 937-644-8117 dellinger.6@osu.</p><p>edu</p><p>Curtis Young Ext Educ,</p><p>ANR</p><p>Van Wert 419-238-1214 young.2@osu.</p><p>edu</p><p>Jessica Bowen Ext Educ,</p><p>ANR</p><p>Vinton 740-596-5212 bowen.279@osu.</p><p>edu</p><p>Greg Meyer Ext Educ,</p><p>ANR</p><p>Warren 513-695-1311 meyer.213@osu.</p><p>edu</p><p>Marcus McCartney Ext Educ,</p><p>ANR</p><p>Washington 740-376-7431 mccartney.138@</p><p>osu.edu</p><p>Rory Lewandowski Ext Educ,</p><p>ANR</p><p>Wayne 330-264-8722 lewandowski.11@</p><p>osu.edu</p><p>VACANT VACANT Ext Educ,</p><p>ANR</p><p>Williams 419-636-5608 VACANT</p><p>Alan Sundermeier Ext Educ,</p><p>ANR</p><p>Wood 419-354-9040 sundermeier.5@</p><p>osu.edu</p><p>VACANT VACANT Ext Educ,</p><p>ANR</p><p>Wyandot 419-294-4931 VACANT</p><p>For a list of PSU county offices and Extension educators, visit</p><p>extension.psu.edu/county-offices.</p><p>279</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>279</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>WEBSITES</p><p>Agronomic Crops Team,</p><p>The Ohio State University</p><p>agcrops.osu.edu</p><p>Agronomic Crops Insects</p><p>entomology.osu.edu,</p><p>extension.psu.edu/</p><p>publications/agrs-026</p><p>Crop Observation and</p><p>Recommendation Network</p><p>(C.O.R.N.) Newsletter,</p><p>The Ohio State University</p><p>corn.osu.edu</p><p>Entomology, The Ohio State</p><p>University</p><p>entomology.osu.edu</p><p>Horticulture and Crop Science,</p><p>The Ohio State University</p><p>hcs.osu.edu</p><p>Horticulture and Crop Science—</p><p>Weeds, The Ohio State</p><p>University</p><p>agcrops.osu.edu/specialists/</p><p>weeds</p><p>IPM Program, The Ohio State</p><p>University</p><p>ipm.osu.edu</p><p>Penn State Field Crop News</p><p>newsletter</p><p>extension.psu.edu/email-</p><p>preferences</p><p>Penn State Soybean Variety</p><p>Tests, Pennsylvania State</p><p>University</p><p>extension.psu.edu/plants/</p><p>crops/grains/soybeans/</p><p>soybean-variety-tests</p><p>Plant Pathology, The Ohio State</p><p>University</p><p>plantpath.osu.edu</p><p>Plant Pathology, Field Crop</p><p>Diseases, The Ohio State</p><p>University</p><p>plantpath.osu.edu/extension-</p><p>outreach/agronomic-crops,</p><p>u.osu.edu/osusoybeandisease,</p><p>u.osu.edu/ohscn</p><p>Ohio Crop Performance Trials,</p><p>The Ohio State University</p><p>u.osu.edu/perf/</p><p>Ohioline, The Ohio State</p><p>University</p><p>ohioline.osu.edu</p><p>Ohio Soybean Association soyohio.org</p><p>http://agcrops.osu.edu</p><p>http://entomology.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>http://extension.psu.edu/publications/agrs-026</p><p>http://corn.osu.edu</p><p>http://entomology.osu.edu</p><p>http://hcs.osu.edu</p><p>http://agcrops.osu.edu/specialists/weeds</p><p>http://agcrops.osu.edu/specialists/weeds</p><p>http://ipm.osu.edu</p><p>http://extension.psu.edu/email-preferences</p><p>http://extension.psu.edu/email-preferences</p><p>http://extension.psu.edu/plants/crops/grains/soybeans/soybean-variety-tests</p><p>http://extension.psu.edu/plants/crops/grains/soybeans/soybean-variety-tests</p><p>http://extension.psu.edu/plants/crops/grains/soybeans/soybean-variety-tests</p><p>http://plantpath.osu.edu</p><p>http://plantpath.osu.edu/extension-outreach/agronomic-crops, u.osu.edu/osusoybeandisease</p><p>http://plantpath.osu.edu/extension-outreach/agronomic-crops, u.osu.edu/osusoybeandisease</p><p>http://plantpath.osu.edu/extension-outreach/agronomic-crops, u.osu.edu/osusoybeandisease</p><p>http://u.osu.edu/ohscn</p><p>http://u.osu.edu/perf/</p><p>http://ohioline.osu.edu</p><p>http://soyohio.org</p><p>280</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>280</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>Ohio Corn Growers Association</p><p>and Ohio Wheat Growers</p><p>Association</p><p>ohiocornandwheat.org</p><p>Soil Fertility</p><p>soilfertility.osu.edu/home,</p><p>nutrientmanagement.osu.</p><p>edu/field-ohio, agsci.psu.edu/</p><p>aasl/soil-testing/soil-fertility-</p><p>testing/handbooks/agronomic</p><p>Soybeans, Pennsylvania State</p><p>University</p><p>extension.psu.edu/plants/</p><p>crops/grains/soybeans</p><p>Soybean and Small Grain Crop</p><p>Production, The Ohio State</p><p>University</p><p>stepupsoy.osu.edu</p><p>USDA-Ohio Crop/Weather</p><p>releases</p><p>nass.usda.gov/Statistics_by_</p><p>State/Ohio/Publications/Crop_</p><p>Progress_&_Condition/</p><p>POISON INFORMATION CENTERS</p><p>NATIONAL POISON CONTROL CENTER</p><p>800-222-1222</p><p>This number will automatically connect you to the center closest to you.</p><p>OHIO POISON CONTROL CENTERS</p><p>Cincinnati</p><p>Drug and Poison Information Center</p><p>University of Cincinnati</p><p>Children’s Hospital</p><p>Medical Center, Room 7701</p><p>3333 Burnet Ave., ML 9004</p><p>Cincinnati, OH 45229-3026</p><p>513-558-5111</p><p>Columbus</p><p>Central Ohio Poison Center</p><p>Children’s Hospital</p><p>700 Children’s Drive</p><p>Columbus, OH 43205</p><p>614-228-1323</p><p>614-228-2272 (TTY)*</p><p>*Phone number for the deaf.</p><p>http://ohiocornandwheat.org</p><p>http://soilfertility.osu.edu/home</p><p>http://nutrientmanagement.osu.edu/field-ohio</p><p>http://nutrientmanagement.osu.edu/field-ohio</p><p>http://agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks/agronomic</p><p>http://agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks/agronomic</p><p>http://agsci.psu.edu/aasl/soil-testing/soil-fertility-testing/handbooks/agronomic</p><p>http://extension.psu.edu/plants/crops/grains/soybeans</p><p>http://extension.psu.edu/plants/crops/grains/soybeans</p><p>http://stepupsoy.osu.edu</p><p>http://nass.usda.gov/Statistics_by_State/Ohio/Publications/Crop_Progress_&_Condition/</p><p>http://nass.usda.gov/Statistics_by_State/Ohio/Publications/Crop_Progress_&_Condition/</p><p>http://nass.usda.gov/Statistics_by_State/Ohio/Publications/Crop_Progress_&_Condition/</p><p>281</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>281</p><p>G</p><p>eneral C</p><p>rop M</p><p>anagem</p><p>ent</p><p>PENNSYLVANIA POISON CONTROL CENTERS</p><p>Hershey</p><p>Central Pennsylvania Poison Center</p><p>The Milton S. Hershey Medical Center</p><p>Pennsylvania State University</p><p>MC H043 PO Box 850</p><p>500 University Boulevard</p><p>Hershey, PA 17033-0850</p><p>Emergency: (800) 222-1222</p><p>Philadelphia</p><p>The Poison Control Center</p><p>3535 Market Street</p><p>Suite 985</p><p>Philadelphia, PA 19104-3309</p><p>Emergency: (800) 222-1222</p><p>Pittsburgh</p><p>Pittsburgh Poison Center</p><p>Children's Hospital of Pittsburgh</p><p>3705 Fifth Avenue</p><p>Pittsburgh, PA 15213</p><p>Emergency: (800) 222-1222</p><p>282</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>282</p><p>G</p><p>en</p><p>er</p><p>al</p><p>C</p><p>ro</p><p>p</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>EMERGENCY CONTACTS</p><p>In the event of gross environmental contamination by pesticides, such as</p><p>a spill or fire, contact:</p><p>Ohio Environmental Protection Agency</p><p>24-Hour Emergency Response Group</p><p>50 West Town Street, Suite 700</p><p>Columbus, OH 43215</p><p>Report a spill, release, or environmental crime</p><p>800-282-9378 (in Ohio)</p><p>614-224-0946 (outside Ohio)</p><p>Ohio Department of Agriculture</p><p>Division of Plant Health</p><p>8995 East Main Street, Bldg 23</p><p>Reynoldsburg, OH 43068</p><p>ODA Ph. 800-282-1955</p><p>Division Phone: 614-728-6270</p><p>agri.ohio.gov</p><p>8:00 a.m. to 5:00 p.m., Monday through Friday</p><p>Pennsylvania Department of Agriculture</p><p>2301 North Cameron Street</p><p>Harrisburg, PA 17110</p><p>General information 717-784-4737</p><p>agriculture.pa.gov</p><p>In event of chemical fire, spill, leak, exposure or accident on a highway,</p><p>railway or waterway, contact:</p><p>CHEMTREC</p><p>Washington, D.C.</p><p>800-424-9300</p><p>24 hours a day; 7 days a week</p><p>http://agri.ohio.gov</p><p>http://agriculture.pa.gov</p><p>283</p><p>Index</p><p>INDEX</p><p>CORN</p><p>Abiotic Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25–26</p><p>Diseases</p><p>Examples of corn leaf damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48</p><p>Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49–71</p><p>Time of occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47</p><p>Submitting plant samples to lab.. . . . . . . . . . . . . . . . . . . . . . . . . . . . 245–247</p><p>Sampling grain for mycotoxins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .248</p><p>Ear Abnormalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18–24</p><p>Fertility</p><p>Estimating nitrogen loss . . . .</p><p>. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81–82</p><p>Nitrogen recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79–80</p><p>Nutrient deficiency symptoms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72–78</p><p>Nutrient sufficiency ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88</p><p>Fertilizer recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86–87</p><p>Growth Staging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4–7</p><p>Insects</p><p>Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29–42</p><p>Scouting calendar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27</p><p>Submitting insect samples to lab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244</p><p>Miscellaneous</p><p>Effect of planting date on grain yields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9</p><p>Estimating pre-harvest yields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14</p><p>Flooding and ponding damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11</p><p>Sampling insects and plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244–247</p><p>Seed spacing for plant populations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15</p><p>Replant Decisions</p><p>Determining corn growth stages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4–7</p><p>Information required for replant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8–10</p><p>Yield loss due to defoliation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12</p><p>Weeds</p><p>Herbicide injury diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43–45</p><p>Weed threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46</p><p>FORAGES</p><p>Diseases</p><p>Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 180–188</p><p>Submitting plant samples to lab . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245–247</p><p>Scouting calendar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .177</p><p>Fertility</p><p>Nutrient deficiency symptoms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194–195</p><p>Nutrient sufficiency ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196</p><p>Fertilizer recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197</p><p>284</p><p>In</p><p>de</p><p>x</p><p>Insects</p><p>Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178–179</p><p>Scouting calendar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .177</p><p>Submitting insect samples to lab. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244</p><p>Miscellaneous</p><p>Stand evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 189</p><p>GENERAL MANAGEMENT</p><p>Fertilizer recommendations</p><p>Corn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87–88</p><p>Forages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 197</p><p>Soybeans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136</p><p>Wheat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173</p><p>Insects, mites identification</p><p>Corn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29–42</p><p>Forages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178–179</p><p>Soybeans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96–105</p><p>Wheat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145–150</p><p>Submitting insect samples to lab. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244</p><p>Manure management</p><p>Manure spreader calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .255</p><p>Sampling manure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .253</p><p>Nutrient deficiency symptoms</p><p>Corn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72–78</p><p>Forages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194–195</p><p>Soybeans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .131–134</p><p>Wheat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .169-170</p><p>Nutrient removal by crop</p><p>Corn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86</p><p>Soybeans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136</p><p>Wheat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173</p><p>Nutrient sufficiency ranges</p><p>Corn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88</p><p>Forages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196</p><p>Soybeans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135</p><p>Wheat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172</p><p>Soil pH for crops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .262</p><p>Submitting plant samples to lab . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245–247</p><p>Using the kernal milkline as a guide in silage harvest . . . . . . . . . . . . . . . . . . .17</p><p>Sampling</p><p>Digital sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247</p><p>Disease and disorder sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245–247</p><p>Manure Sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253–254</p><p>Mycotoxin sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .248</p><p>Nematode sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246–247</p><p>Plant tissue analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .250–252</p><p>Soil sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .249–250</p><p>Where to send plant samples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .246</p><p>285</p><p>Index</p><p>Soil</p><p>Evaluating soil health . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .259</p><p>Soil compaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257</p><p>Soil testing P issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .264</p><p>Temperature development units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260–261</p><p>Miscellaneous</p><p>Area and volume calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .268–269</p><p>Conversion factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270–272</p><p>Emergency contacts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .282</p><p>Extension educators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 275–278</p><p>Field crop Extension specialists. . . . . . . . . . . . . . . .</p><p>. . . . . . . . . . . . . 273–274</p><p>Length of row to equal 1/1000 acre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .268</p><p>POISON CONTROL TELEPHONE NUMBERS . . . . . . . . . . . . . . . 280–281</p><p>Websites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279–280</p><p>PESTICIDE APPLICATION TECHNOLOGY</p><p>Application principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227–228</p><p>Calibration</p><p>Calibrating granular applicators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .238</p><p>Calibrating sprayer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .232</p><p>Calibration equations for liquid applications. . . . . . . . . . . . . . . . . . . . . . .242</p><p>Even flat-fan band widths. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .240</p><p>Head scab application technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241</p><p>Selecting Nozzles</p><p>Choosing appropriate size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .229</p><p>Effects of nozzle type on coverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .236</p><p>Nozzle heights for spray pattern. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .240</p><p>Nozzle types for various uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .239</p><p>SOYBEAN</p><p>Abiotic Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91–92</p><p>Diseases</p><p>Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110–130</p><p>Time of occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109</p><p>Submitting plant samples to lab. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245–247</p><p>Fertility</p><p>Nutrient deficiency symptoms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .131–134</p><p>Nutrient sufficiency ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135</p><p>Fertilizer recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136</p><p>Growth Stage Definitions</p><p>Vegetative and reproductive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90</p><p>Insects, Mites</p><p>Aphid speed scouting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104</p><p>Estimating leaf damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95</p><p>Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96–105</p><p>Pest assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94</p><p>Scouting calendar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93</p><p>286</p><p>In</p><p>de</p><p>x</p><p>Submitting insect samples to lab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244</p><p>Miscellaneous</p><p>Sampling insects and plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244–247</p><p>Replant decisions</p><p>Information needed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137–139</p><p>Estimating leaf damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95</p><p>Determining plant population . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139</p><p>Yield loss from defoliation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138</p><p>Weeds</p><p>Herbicide injury diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107–108</p><p>Weed threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106</p><p>WEEDS</p><p>Identification</p><p>Scouting: how and when . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 198–199</p><p>Grass key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .202–203</p><p>Annual grass weeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .204–206</p><p>Perennial grass weeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207</p><p>Broadleaf weed ID key . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .208–211</p><p>Summer annual broadleaf weeds . . . . . . . . . . . . . . . . . . . . . . . . . . . 212–219</p><p>Winter annual broadleaf weeds . . . . . . . . . . . . . . . . . . . . . . . . . . . .220–222</p><p>Biennial broadleaf weeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223</p><p>Perennial broadleaf weeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224–226</p><p>Threshold</p><p>Corn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46</p><p>Soybean. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106</p><p>WHEAT</p><p>Diseases</p><p>Disease assessment keys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152–153</p><p>Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154–167</p><p>Submitting plant samples to lab . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245–247</p><p>Thresholds for foliar fungicides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168</p><p>Time of occurrence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151</p><p>Head scab application technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241</p><p>Sampling grain for mycotoxin analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .248</p><p>Fertility</p><p>Nitrogen recommendation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171</p><p>Nutrient deficiency symptoms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..169–170</p><p>Nutrient sufficiency ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172</p><p>Fertilizer recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173</p><p>Freeze damage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143</p><p>Growth Stages</p><p>The Feekes Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141</p><p>Insects</p><p>Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145–150</p><p>287</p><p>Index</p><p>Scouting calendar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144</p><p>Submitting insect samples to lab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244</p><p>288</p><p>289</p><p>OHIO STATE UNIVERSITY EXTENSION</p><p>CORN, SOYBEAN, WHEAT, AND FORAGES</p><p>FIELD GUIDE</p><p>Wheat . . . . . . . . . . . . . . . . . . . . . . . . . 140–173</p><p>Weeds . . . . . . . . . . . . . . . . . . . . . . . . 198–226</p><p>Forages . . . . . . . . . . . . . . . . . . . . . . . .174–197</p><p>Soybean . . . . . . . . . . . . . . . . . . . . . . . . 89–139</p><p>Corn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–88</p><p>Pesticide Application Technology . 227–242</p><p>General Crop Management . . . . . .243–282</p><p>827–JAN19–Q31373</p><p>CORN, SOYBEAN, WHEAT AND FORAGES FIELD GUIDE</p><p>AUTHORS</p><p>ACKNOWLEDGMENTS</p><p>CORN MANAGEMENT</p><p>STAGING VEGETATIVE GROWTH IN CORN</p><p>INFORMATION REQUIRED TO MAKE A CORN REPLANTING DECISION</p><p>ASSESSING FLOODING AND PONDING DAMAGE TO CORN</p><p>ESTIMATED PERCENTAGE CORN GRAIN YIELD LOSS DUE TO DEFOLIATION AT VARIOUS GROWTH STAGES</p><p>EFFECTS OF PLANT DAMAGE DURING GRAIN FILL IN CORN</p><p>ESTIMATING CORN YIELDS PRIOR TO HARVEST</p><p>ESTIMATING CORN SILAGE YIELDS</p><p>SEED SPACING FOR PLANT POPULATIONS</p><p>GROWING DEGREE DAY ACCUMULATION NORMALS FROM APRIL 1—OHIO</p><p>USING THE KERNEL MILKLINE AS A GUIDE IN SILAGE HARVEST</p><p>ABNORMAL CORN EARS</p><p>ABIOTIC STRESS IN CORN</p><p>INSECT SCOUTING CALENDAR FOR CORN</p><p>CORN PESTS</p><p>HERBICIDE INJURY DIAGNOSIS—CORN</p><p>WEED THRESHOLD INFORMATION FOR CORN</p><p>TIME OF DISEASE OCCURRENCE IN CORN</p><p>EXAMPLES OF CORN LEAF DAMAGE</p><p>CORN DISEASES</p><p>NUTRIENT DEFICIENCY SYMPTOMS IN CORN</p><p>OTHER NUTRIENT DEFICIENCY SYMPTOMS IN CORN</p><p>OHIO RECOMMENDED CORN NITROGEN FERTILIZER RATES</p><p>ESTIMATING NITROGEN LOSSES AFTER A SPRING FERTILIZER APPLICATION</p><p>PRE-SIDEDRESS NITRATE TEST (PSNT) FOR MANURED FIELDS</p><p>THE EARLY SEASON CHLOROPHYLL METER NITROGEN TEST FOR CORN</p><p>OHIO FERTILIZER RECOMMENDATIONS IN POUNDS PER ACRE (POAND KO) FOR CORN FOR GRAIN WHEN SOIL TESTS ARE IN THE MAINTENANCE RANGE*</p><p>OHIO FERTILIZER (PO AND KO) RECOMMENDATIONS FOR CORN SILAGE IN POUNDS PER ACRE</p><p>NUTRIENT SUFFICIENCY RANGES FOR CORN</p><p>SOYBEAN MANAGEMENT</p><p>DESCRIPTION OF VEGETATIVE AND REPRODUCTIVE STAGES</p><p>ABIOTIC STRESS IN SOYBEANS</p><p>INSECT SCOUTING CALENDAR FOR SOYBEAN</p><p>SOYBEAN PEST ASSESSMENT METHODS</p><p>SOYBEAN DEFOLIATION LEVELS</p><p>SOYBEAN PESTS</p><p>OTHER INSECT DEFOLIATORS</p><p>YIELD REDUCTION FROM WEEDS IN SOYBEANS</p><p>HERBICIDE INJURY DIAGNOSIS SOYBEANS</p><p>TIME OF DISEASE SYMPTOM OCCURRENCE ON SOYBEANS</p><p>SOYBEAN DISEASES</p><p>STEM AND LATE SEASON DISEASES</p><p>VIRUS DISEASES OF SOYBEAN</p><p>NUTRIENT DEFICIENCY SYMPTOMS IN SOYBEAN</p><p>NUTRIENT SUFFICIENCY RANGES FOR SOYBEANS</p><p>OHIO FERTILIZER RECOMMENDATIONS IN POUNDS PER ACRE (POAND KO) FOR SOYBEAN WHEN SOIL TESTS ARE IN THE MAINTENANCE RANGE*</p><p>SOYBEAN STAND EVALUATION AND REPLANT DECISIONS</p><p>ESTIMATING SOYBEAN YIELD</p><p>WHEAT MANAGEMENT</p><p>WHEAT GROWTH STAGES</p><p>WHEAT STAND EVALUATION</p><p>FREEZE DAMAGE</p><p>INSECT SCOUNTING CALENDAR FOR WHEAT</p><p>WHEAT PESTS</p><p>TIME OF DISEASE OCCURRENCE ON WHEAT</p><p>DISEASE ASSESSMENT KEYS FOR DETERMINING SEVERITY BASED ON PERCENTAGE OF SPIKE AND LEAF AREA DISEASED</p><p>DISEASE ASSESSMENT KEYS FOR DETERMINING SEVERITY BASED ON PERCENTAGE OF LEAF AREA DISEASED</p><p>WHEAT DISEASES</p><p>WHEAT DISEASE THRESHOLDS FOR FOLIAR FUNGICIDES</p><p>NUTRIENT DEFICIENCY SYMPTOMS IN WHEAT</p><p>NITROGEN RECOMMENDATIONS FOR WHEAT BASED ON YIELD POTENTIAL</p><p>NUTRIENT SUFFICIENCY RANGES FOR WHEAT</p><p>OHIO FERTILIZER RECOMMENDATIONS IN POUNDS PER ACRE (PO AND KO) FOR WHEAT FOR GRAIN WHEN SOIL TESTS ARE IN THE MAINTENANCE RANGE*</p><p>FORAGE MANAGEMENT</p><p>GROWTH AND DEVELOPMENT OF FORAGES</p><p>SCOUTING CALENDAR FOR ALFALFA</p><p>FORAGE PESTS</p><p>ALFALFA DISEASES</p><p>DISEASES OF FORAGE GRASSES</p><p>ALFALFA STAND EVALUATION</p><p>ALFALFA RESEEDING GUIDELINES</p><p>ESTIMATING ALFALFA QUALITY IN THE FIELD</p><p>ESTIMATING ALFALFA NDF IN FIELD</p><p>FORAGE HARVEST MANAGEMENT</p><p>NUTRIENT DEFICIENCY SYMPTOMS IN ALFALFA</p><p>NUTRIENT SUFFICIENCY RANGES IN FORAGES</p><p>OHIO FERTILIZER (PO AND KO) RECOMMENDATIONS FOR ALFALFA IN POUNDS PER ACRE</p><p>WEED IDENTIFICATION</p><p>WEED SCOUTING OVERVIEW</p><p>GRASS AND GRASSLIKE WEED VEGETATIVE KEY</p><p>ANNUAL GRASS WEEDS</p><p>PERENNIAL GRASS WEEDS</p><p>BROADLEAF WEED VEGETATIVE KEY</p><p>SUMMER ANNUAL BROADLEAF WEEDS</p><p>WINTER ANNUAL BROADLEAF WEEDS</p><p>BIENNIAL BROADLEAF WEEDS</p><p>PERENNIAL BROADLEAF WEEDS</p><p>PESTICIDE APPLICATION TECHNOLOGY</p><p>SELECT THE BEST EQUIPMENT/NOZZLE TYPE FOR THE JOB</p><p>APPROVED NOZZLES AND OPERATING PRESSURES: 2,4-D AND DICAMBA FORMULATIONS*</p><p>NOZZLE TYPES FOR USE ON FIELD CROPS</p><p>EVEN FLAT-FAN NOZZLE HEIGHT FOR VARIOUS BAND WIDTHS</p><p>FLAT-FAN NOZZLE HEIGHT FOR VARIOUS SPRAY PATTERN ANGLES</p><p>RELATIVE WEAR OF NOZZLE MATERIALS*</p><p>FUNGICIDE APPLICATION TECHNOLOGY FOR HEAD SCAB MANAGEMENT</p><p>CALIBRATION EQUATIONS FOR LIQUID APPLICATIONS</p><p>GENERAL CROP MANAGEMENT</p><p>SAMPLING</p><p>SUBMITTING INSECT SAMPLES</p><p>SUBMITTING PLANT SAMPLES FOR DISEASE AND DISORDER DIAGNOSIS</p><p>SAMPLING GRAIN FOR MYCOTOXIN ANALYSIS</p><p>COLLECTING A SOIL SAMPLE FOR SOIL TESTING</p><p>PLANT TISSUE ANALYSIS</p><p>PLANT PART TO SAMPLE FOR FOLIAR SAMPLES</p><p>SAMPLING MANURE</p><p>MANURE SPREADER CALIBRATION</p><p>SOIL MANAGEMENT</p><p>TEMPERATURE DEVELOPMENT UNITS</p><p>ESTIMATING SURFACE RESIDUE COVER</p><p>SOIL pH RECOMMENDED FOR VARIOUS CROPS ON VARIOUS SOILS</p><p>OHIO LIME RECOMMENDATIONS</p><p>SOIL TESTING P ISSUES</p><p>OPTIMUM NUTRIENT LEVELS FOR AGRONOMIC CROPS</p><p>CROP AND SOIL CONDITIONS WHERE SECONDARY AND MICRONUTRIENT DEFICIENCIES MAY OCCUR</p><p>MICRONUTRIENT SOURCES COMMONLY USED FOR CORRECTING MICRONUTRIENT DEFICIENCIES IN PLANTS</p><p>LENGTH OF ROW EQUAL TO 1/1000TH ACRE</p><p>AREA AND VOLUME CALCULATIONS</p><p>CONVERSION FACTORS</p><p>FIELD CROP EXTENSION SPECIALISTS</p><p>EXTENSION EDUCATORS</p><p>WEBSITES</p><p>POISON INFORMATION CENTERS</p><p>EMERGENCY CONTACTS</p><p>INDEX</p><p>plants. Wireworms are</p><p>most common in corn following sod, old hay fields, or equivalent grassy</p><p>conditions.</p><p>Sampling: Preplant detection of wireworms may be achieved by</p><p>making five random digs and inspecting approximately a square foot</p><p>of soil at each dig. Placement of bait traps of grain covered with black</p><p>plastic also enables early detection.</p><p>Economic Threshold: Preventive treatment is warranted when</p><p>wireworms are easily detected.</p><p>Management Options: Where a field has a history of wireworms,</p><p>preventive treatment with a seed treatment or soil insecticide is</p><p>warranted. Rescue treatment of wireworms following emergence is not</p><p>an option. For more information, visit aginsects.osu.edu and extension.</p><p>psu.edu/publications/agrs-026.</p><p>Larva Larva and Damage</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>http://extension.psu.edu/publications/agrs-026</p><p>31</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>31</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>BLACK CUTWORM</p><p>Identification and Incidence:</p><p>Loss of stand prior to emergence</p><p>or due to above-ground cutting</p><p>(see figure) or below-ground</p><p>tunneling (see figure). injury</p><p>indicates presence of black</p><p>cutworms, which are dark-colored</p><p>larvae with minimal markings</p><p>ranging in size from 1/2 inch to 2 inches in length. Incidence of black</p><p>cutworm injury increases as tillage is reduced and when broadleaf</p><p>weeds are abundant prior to planting.</p><p>Sampling: Check 20 plants in five locations weekly for cutworm</p><p>injury beginning after initial emergence of corn. Determine percentage</p><p>of plants being damaged and collect a number of cutworm larvae to</p><p>determine the predominant stage of larval development. Populations</p><p>of moths can be sampled using plastic pheromone traps (available</p><p>from a variety of suppliers), then degree-day accumulation can be</p><p>used to predict larval damage. Degree-day accumulation begins when</p><p>pheromone traps capture eight or more males over two nights, then</p><p>cutting activity tends to occur after about 300 degree days.</p><p>Economic threshold: If corn is in the 2- or 3-leaf stage, an additional</p><p>three or four plants may be affected for every plant exhibiting fresh</p><p>injury. If corn has reached the 5- or 6-leaf stage, additional stand injury</p><p>will be minimal. Rescue treatment should be based on estimated</p><p>additional stand loss.</p><p>Management Options: Reduced tillage or no-tillage fields with</p><p>substantial broadleaf weed infestations may warrant preventive</p><p>treatment. If preventive treatment is not applied, rescue treatment</p><p>may be applied if severe infestations are detected early. Early tillage</p><p>and good weed control will reduce incidence of cutworm infestation.</p><p>For more information, visit aginsects.osu.edu and extension.psu.edu/</p><p>publications/agrs-026.</p><p>5 mm</p><p>Larva and damage</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>http://extension.psu.edu/publications/agrs-026</p><p>32</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>32</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>COMMON STALK BORER</p><p>Identification and Incidence: Common stalk borer overwinters in</p><p>egg stage on various plants, especially grassy weeds. Eggs hatch in</p><p>May or June and larvae develop on their host plants moving to corn</p><p>when host plant is killed or too small for the larva. Larvae are marked</p><p>with white and purple-brown stripes. They are about 1½ inches in</p><p>length when full grown.</p><p>Sampling: Sample 20 plants in five places recording damaged plants.</p><p>Record larval size, stage of larval development, and location of stalk</p><p>borer larva in the plant.</p><p>Economic Threshold: Rescue treatment may be necessary when 3</p><p>percent or more of the stand is being damaged and before the larvae</p><p>have burrowed deep into the plants.</p><p>Management Options: Good weed control will reduce the incidence</p><p>of stalk borer. For more information, visit aginsects.osu.edu and</p><p>extension.psu.edu/publications/agrs-026.</p><p>Larva Damage</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>33</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>33</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>FLEA BEETLES</p><p>Identification and Incidence: Tiny black insects less than an ⅛</p><p>inch long that feed on newly emerging corn plants. Flea beetle activity</p><p>is indicated by “windowpane” feeding on the leaves. The corn flea</p><p>beetle is a vector of Stewart’s wilt. They are normally more of a problem</p><p>following a mild winter.</p><p>Sampling: Check 20 plants in five places for flea beetles on newly</p><p>emerging corn plants. Record percentage of plants with feeding,</p><p>severity of feeding, and whether or not beetles are present.</p><p>Economic Threshold: Treatment is warranted if 3 percent or more of</p><p>the plants are wilting/dying. Flea beetle control can be accomplished</p><p>by either foliar sprays or seed treatments at planting time.</p><p>Management Options: For more information, visit aginsects.osu.</p><p>edu and extension.psu.edu/publications/agrs-026.</p><p>Adult Damage</p><p>http://aginsects.osu.edu</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>34</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>34</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>SLUGS</p><p>Identification and Incidence: Slugs are not insects, they are</p><p>molluscs and more closely related to snails and clams than to insects. In</p><p>field crops, slugs are particularly prevalent in no-till or reduced-till fields</p><p>with heavy residue and little soil disturbance.</p><p>They can eat virtually all crops and inflict most of their damage during</p><p>crop establishment and early growth in the spring and fall. This damage</p><p>tends to be most severe under cool, wet conditions, which slow crop</p><p>growth and favor slug activity. Slugs typically feed at night and hide in</p><p>residue or soil during the day.</p><p>They range in color from pale cream to gray to shiny black, and range</p><p>in size as adults from less than an inch to over 2 inches in length. Small</p><p>juvenile slugs can damage seeds and seedlings, reducing stand and</p><p>may defoliate established stands that may delay plant development.</p><p>Sampling: Inspect 20 plants in five areas of the field and determine</p><p>percentage of plants being fed upon and percentage of defoliation.</p><p>Another approach to finding slugs is to place artificial shelters across a</p><p>field (we use 1 X 1 foot pieces of white roofing shingles, but one could</p><p>also use old boards or anything that will create a dark, cool, moist</p><p>environment). Several days after putting them out, slugs can be found</p><p>under the shelters during the day.</p><p>35</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>35</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>SLUGS (CONT.)</p><p>Research suggests that if you consistently find one to two slugs per</p><p>shingle in the early season that you may end up with damage. In</p><p>autumn, scouting for eggs can also reveal details on populations to</p><p>expect in spring. It is important to note, however, that damage to corn,</p><p>in particular, often looks worse than it is. Research has not been able to</p><p>identify consistent relationship between the amount of slug damage to</p><p>corn plants and yield loss.</p><p>Economic Threshold: Treatment may be necessary if defoliation</p><p>is greater than 40 percent on slow growing plants or if more than 3</p><p>percent of the plants are being killed.</p><p>Management Options: Several bait formulations of metaldehyde</p><p>or chelated iron are labeled for use on corn for slug control. Research</p><p>indicates that ground beetles and other predators can be significant</p><p>allies in the fight against slugs; populations of these predators will be</p><p>strongest in fields that avoid preventative insecticide applications. For</p><p>more information, visit aginsects.osu.edu and extension.psu.edu/</p><p>publications/agrs-026.</p><p>Damage</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>http://extension.psu.edu/publications/agrs-026</p><p>36</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>36</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>COMMON OR TRUE ARMYWORM</p><p>Identification and Incidence: Corn planted no-tillage in grassy</p><p>cover crops, sod, or hay is susceptible to armyworms, which are striped</p><p>larvae that feed on foliage during the pre-whorl and whorl stages.</p><p>Significant armyworm infestation of no-tillage corn following corn or</p><p>soybeans is rare.</p><p>Sampling: High risk no-tillage corn planted in</p><p>grassy ground cover</p><p>should be inspected regularly. Inspect 20 plants in five locations</p><p>and determine percentage of plants damaged and collect a number</p><p>of armyworm larvae to determine the predominant stage of larval</p><p>development.</p><p>Economic Threshold: If 25 percent of a stand or more exhibits</p><p>armyworm injury and potential stand defoliation of 50 percent or more</p><p>is anticipated, rescue treatment is warranted. If less than 25 percent</p><p>of a stand is infested, inspections should be repeated days later until</p><p>status of infestation is resolved.</p><p>Management Options: High-risk corn stands that cannot be</p><p>scouted may warrant use of preventive treatment. Scouting and rescue</p><p>treatment is preferred since armyworm is relatively easy to control</p><p>if detected early. For more information, visit aginsects.osu.edu and</p><p>extension.psu.edu/publications/agrs-026.</p><p>Adult Damage</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>37</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>37</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>CORN ROOTWORM</p><p>Identification and Incidence: Corn root systems exhibiting injury</p><p>ranging from scars to elimination of entire roots or nodes indicates</p><p>presence of rootworms, which are small beetle larvae of either the</p><p>western or northern corn rootworm leaf beetles. Injury occurs during</p><p>June and early July following the hatch of larvae from overwintering</p><p>eggs in the soil. Significant root injury will lead to lodging and a loss in</p><p>yield. Adult rootworm beetles feed on foliage and silks from late July</p><p>through September. Continuous corn is most at risk from damage,</p><p>although in rare occasions and western Ohio locations, first year corn</p><p>may be at a slight risk. Resistance to some below ground Bt varieties</p><p>has been found in surrounding states, but is not known to exist in Ohio</p><p>or Pennsylvania.</p><p>Western adults</p><p>Northern adult Southern adult</p><p>Larva</p><p>38</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>38</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>CORN ROOTWORM (CONT.)</p><p>Sampling and</p><p>Assessment: Potential</p><p>rootworm injury may be</p><p>estimated by monitoring</p><p>the abundance of adult</p><p>rootworm beetles from late</p><p>July to early September in</p><p>fields to be planted to corn</p><p>the following year. Where</p><p>corn is to be planted after</p><p>corn, adult abundance</p><p>may be evaluated by</p><p>visual counts or by using</p><p>yellow sticky traps. Where</p><p>corn is to be planted after</p><p>soybeans, adult activity</p><p>may be evaluated by using</p><p>yellow sticky traps.</p><p>Management Options:</p><p>Crop rotation with soybeans or alfalfa remains the best approach for</p><p>controlling corn rootworm populations. Where a significant potential</p><p>for rootworm injury exists in continuous corn or first year corn following</p><p>soybeans, use of a seed treatment, Bt-transgenic rootworm hybrid, or</p><p>soil insecticide as a preventive treatment will reduce rootworm injury.</p><p>Because of the potential for rootworms to develop resistance to certain</p><p>Bt-transgenic hybrids we recommend not using the same hybrids</p><p>if growing continuous corn. To help prevent resistance, alternate</p><p>transgenic hybrids using different gene products or stacked varieties.</p><p>For more information, visit aginsects.osu.edu and extension.psu.edu/</p><p>publications/agrs-026.</p><p>Damage</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>http://extension.psu.edu/publications/agrs-026</p><p>39</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>39</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>EUROPEAN CORN BORER</p><p>Identification and Incidence: Foliar shot hole injury of mid-whorl</p><p>corn followed by infestation of larvae in stalks in late June or July</p><p>is first brood European corn borer (ECB) injury. Second brood ECB</p><p>larvae infest tassels, ears, and stalks in August and early September.</p><p>In general, first brood ECB is more common in early planted corn, and</p><p>second brood ECB is common in late planted corn. Due to widespread</p><p>adoption of Bt-corn, which kills its caterpillars very effectively, ECB</p><p>populations have been decreasing across the eastern Corn Belt.</p><p>Sampling: To evaluate first brood ECB, inspect 20 plants at five or</p><p>more locations weekly during whorl stage. Early detection of second</p><p>brood ECB is difficult. To evaluate second brood ECB, inspect 20 plants</p><p>at five locations for egg masses or early larva.</p><p>Economic Threshold: First Brood: Detection of ECB larvae in 75</p><p>percent or more of stand may warrant treatment if an average of</p><p>one larva per stalk can be prevented from completing development.</p><p>Second Brood: Treatment may be warranted if 50 percent or more of</p><p>the plants have eggs or early larva. Fields having severe second brood</p><p>ECB infestations should be harvested early to minimize stalk lodging</p><p>and ear drop.</p><p>Management Options: If significant ECB infestations are detected</p><p>prior to stalk boring, chemical treatment may be applied. Planting</p><p>of ECB resistant transgenic Bt-corn is a preventive option. For</p><p>more information, visit aginsects.osu.edu and extension.psu.edu/</p><p>publications/agrs-026.</p><p>Larva Larva and damage</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>http://extension.psu.edu/publications/agrs-026</p><p>40</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>40</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>WESTERN BEAN CUTWORM</p><p>Identification and Incidence: Feeding on ear tips or dime-sized</p><p>holes in middle of corn ear is western bean cutworm (WBC) damage.</p><p>May find less than one larvae per ear. Damage occurs from late July</p><p>until end of September.</p><p>Sampling: Milk jug traps with WBC pheromone lures are used to</p><p>monitor adult flight from June through September. Traps are placed</p><p>at edge of cornfield and monitored at least weekly. Once adults are</p><p>caught, inspect corn for eggs or larvae. Sample 20 consecutive plants</p><p>in five different areas of the field. Eggs are laid on upper leaf surfaces.</p><p>In pre-tassel corn, larvae could be found feeding on the tassel in the</p><p>whorl. After tassel emergence, larvae will be found on leaves, but</p><p>eventually will migrate to the silks and ears.</p><p>Economic Threshold: If 5 to 8 percent of plants sampled have either</p><p>eggs or larvae, treatment should be considered. Repeated application</p><p>may be necessary if adult flights continue through August.</p><p>Management Options: Many insecticides are labeled for WBC</p><p>control, and timing of application should be after 95 percent of field has</p><p>tasseled and before larvae enter the ear. Transgenic corn with Cry1F Bt</p><p>gene (Herculex I, Herculex Xtra, Smartstax) or the newer Viptera trait</p><p>has activity against WBC, though Cry1F efficacy in Ohio is decreasing</p><p>and may fail to control WBC. For more information, visit aginsects.osu.</p><p>edu and extension.psu.edu/publications/agrs-026.</p><p>http://aginsects.osu.edu</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>41</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>41</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>GRUBS</p><p>Identification and Incidence:</p><p>Grubs are the larvae of certain</p><p>beetles that can cause significant</p><p>stand loss. While numerous</p><p>species of true white grubs and</p><p>various annual grubs can be</p><p>found in corn fields, none have</p><p>been consistent problems in Ohio.</p><p>Recently a new grub, the Asiatic garden beetle (AGB), more commonly</p><p>found in turf has been causing significant problems in corn, mostly in</p><p>northern Ohio. This is a smaller grub, more active than other grubs, and</p><p>identified by small, white maxillary palps on the side of its mouthparts.</p><p>Problems appear to occur only in first-year corn following soybean and</p><p>in sandy soils.</p><p>Sampling: Currently no sampling procedures for AGB have been</p><p>developed. However, grubs can be located by searching the soil in</p><p>areas without corn plants in the spring.</p><p>Economic Threshold: At this time, there have not been studies on</p><p>the efficacy of insecticides for controlling AGB; the pest is too new</p><p>on corn. However, preventive treatment is warranted if growers have</p><p>experienced stand losses in first-year corn when grown in sandy</p><p>soils. These growers might consider applying a granule or liquid soil</p><p>insecticide.</p><p>Management Options: Transgenic hybrids do not offer control, and</p><p>seed treatments do not seem to control the grub. For more information,</p><p>visit aginsects.osu.edu and extension.psu.edu/publications/agrs-026.</p><p>Larva Damage</p><p>2.5 mm</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>42</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>42</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>CORN LEAF APHID</p><p>Identification and Incidence: At late whorl and early tassel stages</p><p>of corn development, blue-green aphid colonies may develop, which</p><p>generate honeydew that disrupts pollination. Feeding activity of corn</p><p>leaf aphid (CLA) may also delay development of corn under drought</p><p>stress. Populations of corn leaf aphid can be flared by unnecessary</p><p>mid-season applications of insecticides to corn fields, including tank</p><p>mixes with fungicides. Many fields contain small populations of aphids</p><p>and these insecticides can be disproportionately hard on beneficial</p><p>insects that tend to keep aphid populations in check.</p><p>Sampling: Evaluation of CLA is based on inspection of 20 plants at</p><p>three or more locations to determine percentage of stand having CLA</p><p>colonies.</p><p>Economic Threshold: When 50 percent or more of the plants have</p><p>colonies, rescue action may be warranted. Presence of insect predators</p><p>(Lady beetles, etc.) indicate a potential decline in CLA activity.</p><p>Management Options: Heavy infestations on stands under stress</p><p>may warrant rescue treatment. Natural predator activity often controls</p><p>infestations. For more information, visit aginsects.osu.edu and</p><p>extension.psu.edu/publications/agrs-026.</p><p>Corn leaf aphids</p><p>http://aginsects.osu.edu</p><p>http://extension.psu.edu/publications/agrs-026</p><p>43</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>43</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>HERBICIDE INJURY</p><p>DIAGNOSIS—CORN</p><p>GERMINATION/EMERGENCE</p><p>Poor germination and uneven emergence</p><p>• Not typical of herbicide injury, but incorporating pendimethalin (not</p><p>labeled for PPI use in corn) or carryover of trifluralin can cause poor</p><p>emergence. “Clubbed-roots” should be visible.</p><p>Leaf-out underground</p><p>• Acetamide herbicides—metolachlor, s-metolachlor, alachlor,</p><p>dimethenamid—can cause leaf-out under cold and wet conditions.</p><p>Crusted or cloddy soils can also be a cause.</p><p>EMERGENCE TO TASSELING</p><p>Buggy-whipping/twisting/leaf crinkling</p><p>• Characteristic of acetamide herbicides—metolachlor, s-metolachlor,</p><p>alachlor, dimethenamid. Usually occurs under cold and wet soil</p><p>conditions, and is often temporary. Dicamba and/or 2,4-D, especially</p><p>when mixed with an acetamide herbicide, can cause similar symptoms,</p><p>but corn may be rolled tighter and lay more horizontal to soil surface.</p><p>Yield can be reduced when plants fail to unfurl soon enough after</p><p>emergence.</p><p>Stunted plants/interveinal yellowing and/or purpling</p><p>of leaves</p><p>• Carryover or tank contamination from ALS-inhibiting herbicides—</p><p>Scepter, chlorimuron, Pursuit, FirstRate. Check lateral roots for a</p><p>“bottlebrush” appearance. Fields affected by carryover may take on</p><p>an uneven appearance with intermixed areas of stunted and healthy</p><p>plants. Persistence of Scepter increases at soil pH of 5.5 or less and</p><p>under drought conditions. Persistence of chlorimuron increases at soil</p><p>pH above 6.8.</p><p>• Preplant/preemergence applications of Hornet and Python may cause</p><p>injury under cold and wet conditions.</p><p>• Application of products containing nicosulfuron, rimsulfuron,</p><p>primisulfuron, prosulfuron, or flumetsulam, or application of Lightning</p><p>on Clearfield Corn, in the same season as organophosphate soil</p><p>insecticides can cause these symptoms, along with severe leaf margin</p><p>crinkling and “onion-leafing.”</p><p>44</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>44</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>Stunted plants/white leaves and/or shoots</p><p>• Misapplication or drift of glyphosate at a low dose (usually at spike</p><p>stage).</p><p>• Balance or Callisto can cause these symptoms. Severe injury with</p><p>Balance may include stunting, leaves turning necrotic, buggy-whipping,</p><p>and stand loss. Injury with Balance is most common under the following</p><p>conditions: sandy soil types; shallow planting depth (less than 11/2</p><p>inches); cold and wet soil; spray overlaps; soil pH approaching 7.5;</p><p>organic matter less than 1.5 percent.</p><p>Stunted plants/short swollen and/or “clubbed roots”</p><p>• Carryover or misapplication of DNA herbicides—pendimethalin</p><p>or trifluralin.</p><p>White/bleached leaves</p><p>• Misapplication or carryover from Command. The plant will usually grow</p><p>out of slight discoloration. However, if more than 75 percent of the plant</p><p>tissue is white the plant will probably die. Carryover is most likely on</p><p>soils with a pH below 5.5.</p><p>• Postemergence application of Callisto. Increased risk of injury when</p><p>used in the same season as organophosphate insecticides, or when</p><p>mixed with methylated seed oil.</p><p>Leaf burn on leaf margins of older leaves</p><p>• Photosynthetic inhibitors may cause yellowing (chlorosis) of leaf</p><p>margins followed by death (necrosis) of the oldest leaves on the plant.</p><p>Herbicides in this group include atrazine, metribuzin, Lorox, simazine.</p><p>Injury is more likely at soil pH greater than 7.2.</p><p>Speckled to burned leaves</p><p>• Postemergence applications of Aim, Buctril, Cadet, Resource, atrazine</p><p>plus crop oil concentrate, or Callisto (only the first few days after</p><p>application). Effects are usually temporary unless a large portion of</p><p>the plant is brown.</p><p>Yellow to translucent color on new leaves</p><p>• Misapplication or drift of ACCase-inhibiting herbicides—Assure II,</p><p>Fusilade DX, Fusion, Poast/Poast Plus, or clethodim. The whorl will be</p><p>easily pulled from the rest of the plant, and have a collapsed brown tip</p><p>on the end near the growing point.</p><p>Speckled leaves due to drift</p><p>• Aim, Cadet, Cobra, Flexstar/Reflex, Gramoxone Max, Resource, or Ultra</p><p>Blazer drift. Usually only cosmetic injury.</p><p>45</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>45</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>Bent or “goose-necked” stalks/fused brace-roots</p><p>• Postemergence applications of growth regulator herbicides such as</p><p>2,4-D and dicamba. Plants may become brittle and prone to lodging.</p><p>More severe during periods of high temperatures and rapid node</p><p>elongation.</p><p>Veinal chlorosis or browning/collapse at leaf arch/</p><p>buggy-whipping</p><p>• Carryover of fomesafen (Flexstar, Reflex). Most likely where fomesafen</p><p>is applied late in soybeans the prior season and dry conditions occur</p><p>following application. Plants may die in areas of spray overlap, but most</p><p>corn will survive injury.</p><p>POLLINATION</p><p>Poor pollination</p><p>• Late season applications of 2,4-D or dicamba at “tassel” to “dough”</p><p>stages of development.</p><p>• Late applications of Lightning to Clearfield corn.</p><p>• See poor, incomplete kernal set, page 22.</p><p>MATURITY</p><p>Ear Pinching</p><p>• Postemergence broadcast applications of products containing</p><p>nicosulfuron, rimsulfuron, primisulfuron, or flumetsulam after corn has</p><p>reached 6 collars. Ear pinching results from the base of the ear having</p><p>a normal number of kernel rows, while the upper part of the ear has</p><p>about 50 percent fewer rows.</p><p>• See ear pinching, page 18.</p><p>46</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>46</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>WEED THRESHOLD INFORMATION</p><p>FOR CORN</p><p>WEEDS</p><p>% Yield Reduction</p><p>1 2 4 6 8 10</p><p>(Number of weeds/100 ft of row)</p><p>C. Cocklebur or G. Ragweed 4 8 16 28 34 40</p><p>Redroot Pigweed or</p><p>C. Lambsquarters</p><p>12 25 50 100 125 150</p><p>Shattercane (2–3/clump) 6 12 25 50 75 100</p><p>Giant Foxtail (5–8/clump) 10 20 50 100 150 200</p><p>Source: University of Illinois Field Crop Scouting Manual.</p><p>NOTE: All effects are additive. If more than one weed exists, add the effects of</p><p>each yield.</p><p>47</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>47</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>TIME OF DISEASE OCCURRENCE</p><p>IN CORN</p><p>D</p><p>is</p><p>ea</p><p>se</p><p>A</p><p>pr</p><p>M</p><p>ay</p><p>Ju</p><p>ne</p><p>Ju</p><p>l</p><p>A</p><p>ug</p><p>Se</p><p>p</p><p>O</p><p>ct</p><p>Se</p><p>ed</p><p>lin</p><p>g</p><p>B</p><p>lig</p><p>ht</p><p>s</p><p>N</p><p>or</p><p>th</p><p>er</p><p>n</p><p>C</p><p>or</p><p>n</p><p>Le</p><p>af</p><p>B</p><p>lig</p><p>ht</p><p>So</p><p>ut</p><p>he</p><p>rn</p><p>C</p><p>or</p><p>n</p><p>Le</p><p>af</p><p>B</p><p>lig</p><p>ht</p><p>St</p><p>ew</p><p>ar</p><p>t’s</p><p>B</p><p>ac</p><p>te</p><p>ria</p><p>l L</p><p>ea</p><p>f B</p><p>lig</p><p>ht</p><p>A</p><p>nt</p><p>hr</p><p>ac</p><p>no</p><p>se</p><p>L</p><p>ea</p><p>f B</p><p>lig</p><p>ht</p><p>A</p><p>nt</p><p>hr</p><p>ac</p><p>no</p><p>se</p><p>S</p><p>ta</p><p>lk</p><p>R</p><p>ot</p><p>C</p><p>ra</p><p>zy</p><p>T</p><p>op</p><p>M</p><p>ai</p><p>ze</p><p>D</p><p>w</p><p>ar</p><p>f M</p><p>os</p><p>ai</p><p>c</p><p>M</p><p>ai</p><p>ze</p><p>C</p><p>hl</p><p>or</p><p>ot</p><p>ic</p><p>D</p><p>w</p><p>ar</p><p>f</p><p>G</p><p>ra</p><p>y</p><p>Le</p><p>af</p><p>S</p><p>po</p><p>t</p><p>N</p><p>or</p><p>th</p><p>er</p><p>n</p><p>C</p><p>or</p><p>n</p><p>Le</p><p>af</p><p>S</p><p>po</p><p>t</p><p>C</p><p>om</p><p>m</p><p>on</p><p>R</p><p>us</p><p>t</p><p>C</p><p>om</p><p>m</p><p>on</p><p>S</p><p>m</p><p>ut</p><p>G</p><p>ib</p><p>be</p><p>re</p><p>lla</p><p>E</p><p>ar</p><p>R</p><p>ot</p><p>G</p><p>ib</p><p>be</p><p>re</p><p>lla</p><p>S</p><p>ta</p><p>lk</p><p>R</p><p>ot</p><p>D</p><p>ip</p><p>lo</p><p>di</p><p>a</p><p>Ea</p><p>r R</p><p>ot</p><p>D</p><p>ip</p><p>lo</p><p>di</p><p>a</p><p>St</p><p>al</p><p>k</p><p>Ro</p><p>t</p><p>Fu</p><p>sa</p><p>riu</p><p>m</p><p>K</p><p>er</p><p>ne</p><p>l R</p><p>ot</p><p>48</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>48</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>EXAMPLES OF CORN LEAF DAMAGE</p><p>Percentage of Leaf Damaged</p><p>Source: James, C. 1971. A manual of assessment keys for plant diseases. The American</p><p>Phytopathological Society, 3340 Pilot Knob Rd., St. Paul, MN 55121.</p><p>49</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>49</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>CORN DISEASES</p><p>SEEDLING BLIGHTS</p><p>Description: Wilting and dying of young seedlings during and after</p><p>emergence are the first signs of blight. A soft watery rot of the roots,</p><p>mesocotyl and crown are typical symptoms. Seeds with a white or</p><p>pinkish weft of mold around them are indications of seed rot. Various</p><p>seed-borne and soil-borne fungi cause seedling blight. Not to be</p><p>confused with insect injury.</p><p>Location: Statewide, particularly in early planted fields or fields with</p><p>compaction, wet soil or very dry soil and reduced tillage fields when</p><p>emergence has been delayed by cold soil. Cold, wet compacted fields</p><p>have particular problems with seedling blight.</p><p>Time of attack: Blights occur when seedlings are put under stress or</p><p>are subjected for extended periods to conditions limiting rapid growth</p><p>of the young plant. Generally, April through mid-June.</p><p>Management:</p><p>• Fungicide seed treatment</p><p>• Improve drainage</p><p>50</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>50</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>NORTHERN CORN LEAF BLIGHT</p><p>Description: Lesions of northern corn leaf blight (NCLB) are large (1</p><p>to 6 inches long by 1/2 to 1 inch wide), cigar-shaped and brown to tan in</p><p>color. During periods of high humidity, lesions may have grayish-green</p><p>centers due to the production of dark-colored spores on dead tissue.</p><p>Location: NCLB can be found throughout Ohio.</p><p>Time of attack: Wet humid weather favors NCLB, especially during</p><p>periods of heavy dew and fog. Symptoms may occur as early as silking,</p><p>but are more prevalent during later stages of development.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Crop rotation</p><p>• Till residues</p><p>51</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>51</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>SOUTHERN CORN LEAF BLIGHT</p><p>Description: Lesions of southern corn leaf blight (SCLB) are small (1/4-</p><p>to 1 inch long by 1/4 inch wide) and tan in color. Lesions may be oval or</p><p>have parallel sides. On some hybrids, lesions may be surrounded by</p><p>yellow halos, but other hybrids may have reddish-brown borders.</p><p>Location: SCLB can be found throughout Ohio, but is more prevalent</p><p>in the southern half of the state. Usually only occurs on hybrids that lack</p><p>adequate resistance.</p><p>Time of attack: Wet humid weather favors SCLB, especially during</p><p>periods of heavy dew and fog. Symptoms may occur as early as silking,</p><p>but are more prevalent during later stages of development.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Crop rotation</p><p>• Till residues</p><p>52</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>52</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>STEWART’S BACTERIAL LEAF BLIGHT</p><p>Description: Very long necrotic lesions with wavy margins. Some</p><p>lesions extend nearly the length of the leaf on susceptible hybrids.</p><p>Lesions are commonly found connected to small, thin feeding scars left</p><p>by the adult corn flea beetle, which carries the bacterium over winter</p><p>and transmits it to corn while feeding on the leaves in the spring. Sweet</p><p>corn, popcorn, and inbreds may show seedling wilt when attacked</p><p>early, but most hybrid dent corn is more resistant to the seedling phase</p><p>of the disease. All types of corn may be affected by the leaf blight</p><p>phase of the disease. Mild winter conditions favor the survival of the</p><p>flea beetle and as such increase the risk of Stewart’s leaf blight. The</p><p>risk of this disease is high when the sum of the average temperatures</p><p>for the months of December, January, and February exceed 100</p><p>degrees Fahrenheit.</p><p>Location: Stewart’s leaf blight occurs throughout Ohio.</p><p>Time of attack: Attack by adult flea beetles and transmission of the</p><p>bacterium occur soon after seedling emergence. Continued feeding by</p><p>beetles throughout the summer increases the severity of the disease.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Control flea beetle with insecticide foliar spray or seed treatment (see</p><p>insect section on flea beetle)</p><p>53</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>53</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>ANTHRACNOSE LEAF BLIGHT</p><p>Description: Anthracnose lesions on leaves vary greatly in size and</p><p>shape but are generally less than 1 inch long with dark tan centers,</p><p>brown borders and yellowish to orange halos. Lesions generally appear</p><p>first near the tip and midrib of the leaf, later coalescing to produce</p><p>large dead areas and blotches. Black hair-like structures emerging from</p><p>fruiting bodies (acervuli) within lesions can be seen with a hand lens</p><p>during periods of high humidity.</p><p>Location: Leaf blight phases of anthracnose can be found throughout</p><p>the state. It is prevalent in continuous, reduced tillage corn fields.</p><p>Time of attack: The disease is favored by rainy weather any time</p><p>from seedling emergence to maturity.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Till residues</p><p>• Crop rotation</p><p>54</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>54</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>CRAZY TOP</p><p>Description: Affected plants show excessive tillering, rolling of leaves</p><p>during the early stages of development, and/or proliferation of the</p><p>tassels and husks due to abnormal growth of tissues. The tassel on</p><p>affected plants usually resembles a huge mass of leaves clustered</p><p>together.</p><p>Location: Crazy top occurs anywhere in Ohio.</p><p>Time of attack: Saturated soil conditions or ponded water from</p><p>excessive rainfall during early stages of plant growth favor infection.</p><p>Plants become infected as seedlings and the fungus grows systemically</p><p>in the plant causing abnormal development of plant tissues. Symptoms</p><p>are most recognizable from mid-whorl stage of development to</p><p>maturity.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Improve soil drainage</p><p>55</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>55</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>MAIZE DWARF MOSAIC</p><p>Description: Maize dwarf mosaic is a virus disease recognized as</p><p>a mottling or mosaic of light and dark green areas in young leaves</p><p>within the whorl. Later plants may develop leaves that are yellowed or</p><p>reddened and plants may be stunted, but these later symptoms are not</p><p>characteristic for diagnosis.</p><p>Location: Maize dwarf mosaic occurs in river bottom fields where</p><p>johnsongrass occurs in southern Ohio.</p><p>Time of attack: The virus overwinters in johnsongrass. Aphids</p><p>feeding on johnsongrass transmit the maize dwarf mosaic virus to</p><p>young plants. Symptoms may develop on young plants, but diseased</p><p>plants are easier to diagnose in the mid- to late whorl stages of</p><p>development than later in the season.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Destroy johnsongrass</p><p>56</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>56</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>MAIZE CHLOROTIC DWARF</p><p>Description: The characteristic symptom of maize chlorotic dwarf is</p><p>the presence of very fine chlorotic stripes adjacent to the secondary</p><p>veins on leaves in the whorl stages of growth. Older plants become</p><p>severely stunted with yellowing and reddening of the leaves.</p><p>Location: Maize chlorotic dwarf occurs in river bottom fields where</p><p>johnsongrass is a problem in southern Ohio.</p><p>Time of attack: The virus overwinters in Johnson- grass. Leafhoppers</p><p>feeding on johnsongrass transmit the maize dwarf virus to corn plants.</p><p>Symptoms may develop on young plants, but diseased plants are</p><p>easier to diagnose in the mid- to late whorl stages of development than</p><p>later in the season.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Destroy johnsongrass</p><p>57</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>57</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>GRAY LEAF SPOT</p><p>Description: Lesions resemble elongated rectangles on leaf surfaces.</p><p>Lesions have straight or parallel sides. Susceptible type lesions may be</p><p>from 1/2 to 4 inches long and tan to gray in color with no borders. Some</p><p>less susceptible hybrids have yellow halos surrounding small lesions</p><p>(chlorotic lesion type).</p><p>Location: The disease can be found throughout the state at some</p><p>level, but is most prevalent in east central, southern and western</p><p>Ohio.</p><p>Severe epidemics occur in continuous corn, reduced tillage fields in</p><p>river bottoms or in locations with restricted air drainage. Lodging may</p><p>result from excessive leaf blighting.</p><p>Time of attack: The disease is favored by heavy dew, fog or light</p><p>rain. Periods of drying between these periods also is important. Lesions</p><p>generally first appear near tasseling and disease spread occurs until</p><p>maturity.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Till residues</p><p>• Crop rotation</p><p>• Fungicide application on susceptible hybrids in chronic disease areas</p><p>58</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>58</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>NORTHERN CORN LEAF SPOT</p><p>Description: Symptoms of northern corn leaf spot vary among races of</p><p>the fungus that cause the disease. Race 3, which is the most prominent in</p><p>Ohio, produces lesions that are narrow, linear, and grayish-tan to brown</p><p>in color with dark brown borders. The lesions are usually aligned with the</p><p>veins of the leaf and occur in groups.</p><p>Location: NCLS is most prevalent in the northern third of Ohio, but can</p><p>occur throughout the state in years with cooler weather. The disease</p><p>is most prevalent on inbreds in seed production fields and some of</p><p>the more susceptible hybrids. The disease is generally associated with</p><p>continuous corn especially in reduced tillage.</p><p>Time of attack: Lesions are detected after tasseling to crop maturity.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Crop rotation</p><p>• Till residues</p><p>59</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>59</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>COMMON RUST</p><p>Description: Large, cinnamon-brown, oval to oblong pustules</p><p>scattered over surface of leaves.</p><p>Location: Can occur anywhere in the state, but generally more</p><p>common in northern Ohio.</p><p>Time of attack: Rust can be seen as early as late June in years with</p><p>abnormally cool growing conditions. Disease continues to spread until</p><p>plant maturity during periods of cool weather with light rain.</p><p>Management:</p><p>• Resistant hybrids</p><p>60</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>60</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>SOUTHERN RUST</p><p>Description: Small (relative to common rust), reddish-orange, circular</p><p>to oval pustules densely scattered predominantly on the upper surface</p><p>of the leaf. Pustules may also develop on husks, ear shanks, stalks, and</p><p>leaf shealths.</p><p>Location: Can occur anywhere in the state, but generally most</p><p>common and severe in southern Ohio, where conditions are warmer.</p><p>Time of attack: Southern rust may develop as early as June in years</p><p>and locations with warm, humid growing conditions, but in most years it</p><p>usually occurs after tasseling.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Foliar fungicides</p><p>61</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>61</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>COMMON RUST VS SOUTHERN RUST</p><p>Common Rust Southern Rust</p><p>Pustule</p><p>appearance</p><p>Large, oval to elongated,</p><p>scattered over the leaf</p><p>Small, circular, evenly</p><p>distributed over the leaf</p><p>Pustule color</p><p>Brownish to cinnamon-</p><p>brown</p><p>Reddish-orange</p><p>Pustule</p><p>location</p><p>Both upper and lower</p><p>surfaces of leaves.</p><p>Generally, only found on</p><p>leaves</p><p>Predominantly on the</p><p>upper leaf surface. Also</p><p>found on stems and</p><p>husks</p><p>Optimum</p><p>conditions</p><p>Cool (60-77 F) and</p><p>humid conditions</p><p>Warm (77+ F) and humid</p><p>conditions</p><p>Region</p><p>Subtropical and</p><p>temperate regions</p><p>– more common in</p><p>northern Ohio</p><p>Tropical and subtropical</p><p>regions. Most prevalent</p><p>in the south, but may</p><p>occur in the north if</p><p>temperatures increase</p><p>Common Rust Southern Rust</p><p>62</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>62</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>TAR SPOT</p><p>Description: Small, roundish to semi-circular or irregularly shaped,</p><p>black raised spots on both the upper and lower surfaces of the leaf.</p><p>Spots may also develop on leaf sheaths and husks. In some cases, the</p><p>black spot may be surrounded by a necrotic halo which gives the lesion</p><p>an appearance referred to as "fisheye."</p><p>Location: Tar spot was first reported in western Ohio in 2018, but has</p><p>the potential to spread and develop anywhere in the state.</p><p>Time of attack: Moderate temperatures, high relative humidity and</p><p>free moisture favor the development of tar spot. In western Ohio,</p><p>symptoms were first observed after R4 (dough), but the fungus may be</p><p>capable of infecting the corn plant much earlier in the season.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Crop rotation</p><p>• Till residues</p><p>Photo: Eric Richer</p><p>63</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>63</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>COMMON SMUT</p><p>Description: Grayish to white enlarged galls develop on ears, leaf</p><p>surfaces and sometimes tassels. As galls mature, masses of black</p><p>powdery spores are released after rupturing the galls’ outer covering.</p><p>Location: Common smut occurs throughout Ohio on field corn, sweet</p><p>corn and popcorn.</p><p>Time of attack: Common smut spores overwinter in the soil and</p><p>are spread by wind and splashing rain to plant surfaces. Insect, hail or</p><p>mechanical injury increases the incidence of this disease. Smut can be</p><p>detected from tasseling through harvest on ears and on leaves and</p><p>other plant parts nearly anytime.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Control insect pests</p><p>Photo: Felipe Dalla Lana</p><p>64</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>64</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>GIBBERELLA EAR ROT</p><p>Description: Gibberella ear rot is identified by a pink to reddish mold</p><p>that usually begins at the tip of the ear.</p><p>Location: Gibberella ear rot can occur anywhere in Ohio.</p><p>Time of attack: Average daily temperatures below 72 degrees</p><p>Fahrenheit and frequent rain during the first two weeks after silking</p><p>favors Gibberella ear rot. Gibberella rot is associated with several</p><p>mycotoxins, including vomitoxin, that are toxic to livestock.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Crop rotation</p><p>• Balanced fertility</p><p>• Till residues</p><p>• Control insect pests</p><p>Photo: Felipe Dalla Lana</p><p>65</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>65</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>DIPLODIA EAR ROT</p><p>Description: Ears with thick, gray mold that develops from the base</p><p>toward the tip is characteristic of Diplodia ear rot. The kernels appear</p><p>stuck together with the thick layer of mold and the husks adhere to the</p><p>ear.</p><p>Location: Diplodia ear rot is more common in the southern half of</p><p>Ohio and appears to be associated with continuous corn and reduced</p><p>tillage.</p><p>Time of attack: Warm, dry weather prior to silking followed by wet</p><p>conditions following silking favors Diplodia ear rot.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Crop rotation</p><p>• Till residues</p><p>Photo: Justin Petrosino</p><p>66</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>66</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>FUSARIUM EAR OR KERNEL ROT</p><p>Description: Fusarium kernel rot has grayish discoloration of the caps</p><p>of individual kernels or groups of kernels scattered over the ear.</p><p>Location: Fusarium ear rot occurs throughout Ohio.</p><p>Time of attack: Wet, warm weather following silking and damage</p><p>to kernels by insects, hail or other mechanical means favor disease</p><p>development. This kernel rot is associated with a group of mycotoxins</p><p>called Fumonisins that are toxic to livestock.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Crop rotation</p><p>• Till residues</p><p>67</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>67</p><p>C</p><p>orn M</p><p>anagem</p><p>ent</p><p>TRICHODERMA EAR ROT</p><p>Description: Develops as dark green fungal growth on the surface</p><p>and between the kernels of the ear. Severely affected ear may</p><p>germinate (sprout) prematurely.</p><p>Location: Trichoderma ear rot occurs throughout Ohio.</p><p>Time of attack: The development of this disease is favored by warm,</p><p>wet conditions, and is commonly associated with damage caused by</p><p>birds, insects, hail or other mechanical means. Mycotoxins are generally</p><p>not a major concern with Trichoderma ear rot, but some species of the</p><p>fungus that cause the disease do produce toxins.</p><p>Management:</p><p>• Resistant hybrids</p><p>• Till residues</p><p>• Crop rotation</p><p>Photo: Felipe Dalla Lana</p><p>68</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>68</p><p>C</p><p>or</p><p>n</p><p>M</p><p>an</p><p>ag</p><p>em</p><p>en</p><p>t</p><p>SIDE-BY-SIDE COMPARISON OF</p><p>CORN EAR ROTS</p><p>Ear Rot Symptoms</p><p>Favorable</p><p>conditions</p><p>Mycotoxins</p><p>Diplodia</p><p>White fungal growth</p><p>on and between</p><p>kernels and over</p><p>the entire ear. Ears</p><p>become lightweight.</p><p>Warm, dry</p><p>before silking</p><p>followed by</p><p>warm, wet after</p><p>silking.</p>