C.O.R.N. Newsletter: 2022-24
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Weather Update: Ample July Precipitation for Most
Summary
The precipitation pendulum has swung back the other direction for many across the state in July. Figure 1 shows that much of western and central Ohio have picked up more than 150% of normal precipitation, with multiple rounds of showers and storms. CoCoRaHS observations for the month show rainfall totals in the 8–10-inch range for Delaware, Licking, and Franklin Counties in central Ohio. This wet pattern has been accompanied by temperatures running near average for most of Ohio, and 1-3°F above average for counties in the southwest and northeast. The seesaw nature of this year’s growing
season has left highly variable crop conditions, though much of the stress from dry weather in June has been alleviated. For the latest up-to-date conditions, seasonal outlooks, and monthly climate summaries, please visit the State Climate Office of Ohio. Forecast
A front that dropped south of the region on Monday, will edge back northward near the Ohio river on Tuesday and meander there through Thursday. Multiple disturbances will ride eastward along this front, bringing numerous rounds of showers and storms across the state. Most of the activity will be focused south of about I-70, though northern Ohio will not be rainfree. Temperatures will be kept in check, with highs in the 70s expected on Tuesday, and upper 70s to low 80s on Wednesday and Thursday. Dry, tranquil weather will return for Friday through the weekend, with low humidity and mild temperatures. The Weather Prediction Center is forecasting 1.0-3.0 inches of rain for southern counties, tapering to less than 0.5 inch across the north, primarily over the next 3 days (Figure 2).
After this week’s near normal temperatures, the Climate Prediction Center’s 6–10-day outlook for the period of July 31 – August 4, 2022 and the 16-Day Rainfall Outlook from NOAA/NWS/Ohio River Forecast Center show above average temperatures and near average precipitation are expected (Figure 3). Climate averages have reached their annual peak including a high-temperature range of 83-87°F, a low-temperature range of 62-66°F, and average weekly total precipitation of 0.75-0.90 inches. 
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Defoliation in Soybean and Corn
Starting in July and through August, a number of different insect species (such as beetles and various caterpillars) can feed on corn and soybean leaves. Foliage feeding in corn is almost never economic, though economic damage from silk clipping by beetles is possible (though rare). Consider a rescue treatment when silks are clipped to less than ½ inch and, fewer than 50% of the plants have been pollinated, and the beetles are still numerous and feeding in the field.
In soybean, while the defoliation damage from various species might look startling, it is rather rare that this reaches economic levels. Soybeans are master compensators. OSU agronomist Dr. Laura Lindsey reports that she has even weed-whacked large portions of soybean foliage and seen no difference in yield by the end of the season! For defoliating insects in soybean, we usually use an overall defoliation measure as the threshold, regardless of what species is doing the feeding. This helps account for situations where more than one species may be having its bite. Entomologists have recently calculated new thresholds for soybean defoliation based on more modern crop values and input costs. A rescue treatment is advised when defoliation levels reach 30% in pre-bloom stages, 10% during pod development and fill, and 15% at R6 (full seed). After R6, a spray will not pay. These defoliation levels apply to the plant as a whole, not just certain leaves. Damage is often worst at the top of the canopy but on closer examination most of the plant is relatively unharmed. Make your decision based on the average condition of whole plants, not a scan of the top canopy. Also, defoliation tends to be worse on field edges, so make your assessment based on the field as a whole, including interior.
A visual guide to defoliation is useful because it is very easy to over-estimate defoliation in soybean. For more information, visit our new Soybean Defoliation scouting card athttps://aginsects.osu.edu/sites/aginsects/files/imce/Soybean%20defoliation%20Final.pdf
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2022 Ohio Wheat Performance Test- Results Available Online
Results from the 2022 Ohio Wheat Performance Test are now online by clicking HERE.
The purpose of the Ohio Wheat Performance Test is to evaluate wheat varieties, blends, brands, and breeding lines for yield, grain quality, and other important performance characteristics. This information gives wheat producers comparative information for selecting the varieties best suited for their production system and market. Varieties differ in yield potential, winter hardiness, maturity, standability, disease and insect resistance, and other agronomic characteristics. Selection should be based on performance from multiple test sites and years.
In fall 2021, wheat was planted at all five locations within 10 days of the fly-free date. Wheat entered dormancy in good to excellent condition. Cool temperatures and adequate moisture lead to a long grain fill period and high-yielding conditions. A derecho storm in mid-June resulted in higher than average lodging at the Wayne county location, as well as the loss of the disease nursery. Results from Union County were not included in this report due to extreme field variability caused by wildlife. Harvest conditions were favorable and harvest dates average. Overall, grain test weight averaged 58.1 lb/bu (same average test weight in 2021). Grain yield averaged between 87.2 and 111.5 bu/acre among the five locations.
Link to 2022 Ohio Wheat Performance Test: https://ohiocroptest.cfaes.osu.edu/wheattrials/regions.asp?year=2022#single
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Seeding Perennial Forages in Late Summer
August is the second good window of opportunity of the year for establishing perennial forage stands (spring being the first good planting time). August is also the ideal time for filling in gaps in seedings made this spring. The primary risk with late summer forage seedings is having sufficient moisture for seed germination and good plant establishment before cold weather arrives. The decision to plant or not will have to be made for each individual field, considering soil moisture status and the rainfall forecast. Rainfall and adequate soil moisture in the few weeks immediately after seeding is the primary factor affecting successful forage establishment.
No-till Seedings
No-till seeding is an excellent choice to conserve soil moisture for seed germination in late summer. Make sure that the field surface is relatively level and smooth if you plan to no-till, because you will have to live with any field roughness for multiple years of harvesting operations. No-till into wheat stubble would be an excellent option.
Sclerotinia crown and stem rot is a concern with no-till seedings of alfalfa or red clover in late summer in fields with a recent history of clover. This pathogen causes white mold on alfalfa seedlings and infects plants during the cool rainy spells in late October and November. Early August plantings dramatically improve the alfalfa's ability to resist or tolerate the infection. Late August or early September seedings are very susceptible to this disease, with mid-August plantings being intermediate.
In a no-till situation, minimize competition from existing weeds by applying glyphosate burndown before planting. Herbicide-resistant weeds, such as marestail, create a very difficult situation and there are no effective control options in no-till management, so conventional tillage for seedbed prep is probably a better choice in those situations.
Conventional Tillage Seedings
Prepare a firm seedbed to ensure good seed-to-soil contact. Be aware that too much tillage depletes soil moisture and increases the risk of soil crusting. Follow the "footprint guide" that soil should be firm enough for a footprint to sink no deeper than one-half inch. Tilled seedbeds usually do not need a pre-plant herbicide.
Patching Spring Seedings
Where gaps exist in seedings made this spring, it is possible to drill in seed now, even in alfalfa. Autotoxicity will not be a limiting factor in alfalfa seedings made this spring. Alfalfa plants that are less than a year old do not release enough autotoxic compounds into the surrounding soil to harm new seedlings of alfalfa. So, this summer is the last opportunity to try to “patch-in” alfalfa in thin areas of alfalfa stands seeded this spring. By next spring, autotoxicity will be a concern.
Grassy weeds are probably present in thin or weak areas of new spring seedings. As soon as possible, consider applying a grass herbicide to pure legume stands or a broadleaf herbicide if needed in pure grass stands. If broadleaf weeds are present in legume stands or mixed grass-legume stands, effective herbicide options are much more limited, because most broadleaf herbicides labeled for use in alfalfa or other legume forages are only effective when the weeds are quite small. Before applying a herbicide, check the label for pre-plant time intervals that may be required. Use only herbicides with little or no time interval between application and seeding forages. Take a cutting in early August and then immediately drill seed into the thin areas. Try to time drilling the seed when you see some rain in the forecast, especially if the soil is dry.
The following steps improve the chances for stand establishment success regardless of what type of seeding you are making:
- Soil fertility and pH: The recommended soil pH for alfalfa is 6.5 to 6.8. Forage grasses and clovers should have a pH of 6.0 or above. The optimal soil phosphorus level for forage legumes is 30 to 50 ppm Mehlich-3 and for grasses 20 to 30 ppm Mehlich-3. The optimal soil potassium level is 120 to 170 ppm for most of our soils.
- Check herbicide history of field. A summary table of herbicide rotation intervals for alfalfa and clovers is available at http://go.osu.edu/herbrotationintervals. Forage grasses are not included in that table, so check the labels of any herbicides applied to the field in the last 2 years for any restrictions that might exist for forage grass seedings.
- Seed selection: Be sure to use high quality seed of adapted varieties and use fresh inoculum of the proper Rhizobium bacteria for legume seeds. “Common” seed (variety not stated) is usually lower yielding and not as persistent, and from our trials the savings in seed cost is lost within the first year or two through lower forage yields.
- Planting date: Planting of alfalfa and other legumes should be completed between late July and mid-August in Northern Ohio and between early and late August in Southern Ohio. Most cool-season perennial grasses can be planted a little later. Check the Ohio Agronomy Guide for specific guidelines (see http://go.osu.edu/forage-seeding-dates).
- Planter calibration: If coated seed is used, be aware that coatings can account for up to one-third of the weight of the seed. This affects the number of seeds planted in planters set to plant seed on a weight basis. Seed coatings can also dramatically alter how the seed flows through the drill, so calibrate the drill or planter with the seed to be planted and don’t depend on planter calibration charts There is an excellent video on calibrating drills available at https://forages.osu.edu/video.
- Seed placement: The recommended seeding depth for forages is one-quarter to one-half inch deep. It is better to err on the side of planting shallow rather than too deep.
Do not harvest a new perennial forage stand this fall. The ONLY exception to this rule is perennial and Italian ryegrass plantings. Mow or harvest those grasses to a stubble height of two and a half to three-inches in late November to improve winter survival. Do NOT cut any other forage species in the fall, especially legumes.
Scout your new forage seeding this fall on a regular basis. Post-emergence herbicide options exist for alfalfa to control late summer and fall emerging winter annual broadleaf weeds. A mid- to late fall application of Butyrac (2,4-DB), bromoxynil, Pursuit or Raptor are the primary herbicide options for winter annual broadleaf weeds. Fall application is much more effective than a spring application for control of these weeds especially if wild radish/wild turnip are in the weed mix. Pursuit and Raptor can control winter annual grasses in the fall in pure legume stands but cannot be used in a mixed alfalfa/grass planting. Consult the 2022 Weed Contro Guide for Ohio, Indiana, and Illinois (https://extensionpubs.osu.edu/crops/field-crops/) and always read the specific product label for guidelines on timing and rates before applying any product.
- Soil fertility and pH: The recommended soil pH for alfalfa is 6.5 to 6.8. Forage grasses and clovers should have a pH of 6.0 or above. The optimal soil phosphorus level for forage legumes is 30 to 50 ppm Mehlich-3 and for grasses 20 to 30 ppm Mehlich-3. The optimal soil potassium level is 120 to 170 ppm for most of our soils.
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Other Corn Ear Abnormalities – when and why do they develop?
Despite many corn acres having reached tasseling, other corn acres are still in rapidly growing stages, mid to late vegetative. Any adverse conditions can still affect the crop through or prior to harvest. Arrested ears’ occurrence was discussed two weeks ago. Other ear abnormalities of concern up to this point in the season can include tassel ears, fasciated ears, pinched ears, blunt ears, silk-balled ears, incomplete kernel set, banana ears, zipper ears, and tipped back ears.
Based on existing knowledge, table 1 and the following figures present a summary of these abnormalities, including the possible causal factors and their expected timing of development. Plant stages used here are based on the leaf collar method.
Table 1. Summary of various abnormal ear symptoms, their causal factors, and development timing. Adapted from Ortez et al., 2022a.
Symptom
Possible causal factors
Development timing
Figure
1. Tassel ears: ears at the top of tiller plants in place of tassels
Lower populations, end or border rows, growing point damage, genetics
Initiation and differentiation of tiller’s apical meristem into floral structure
1
2. Fasciated ears: increased and non-organized kernel rows
Specific mutants (i.e., genetics), cold temperatures
Ear initiation and development, V4–V7
2
3. Pinched ears: abrupt change to fewer kernel rows in the ear
Cell division inhibitors, for example, sulfonylurea herbicides
Ear size determination period, V6–V12
3
4. Blunt ears: noticeably shorter and stunted ears
Plant stressors (e.g., chemicals or environment), genetics, management
Ear size determination period, V6–V12
4
5. Silk-balled ears: silks fail to elongate toward the ear tip properly
Cold temperatures, drought, genetics
Silk elongation, V12–R1
5
6. Incomplete kernel set: poor or scattered kernel set in the ear
Silks damage, drought, high temperatures, pollination issues, phosphorus shortages, herbicide injury, cloudy days
Pollination, VT or R1; and early reproductive stages, R1–R3
6
7. Banana ears: the curvature of the cob toward a damaged side of the ear
Severe weather, chemical applications, heat or drought, stink bug injury
Pollination, VT or R1; and early reproductive stages, R1–R3
7
8. Zipper ears: ears with missing kernel rows
Higher seeding rates, drought stress, genetics, defoliation, deficient pollination
Pollination, VT or R1; and early reproductive stages, R1–R3
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9. Tipped-back ears: missing kernels at the tip of the ear
Pollen and silk availability, kernel abortion, cloudy days, heat, drought, genetics, higher seeding rates
Pollination, VT or R1; and early reproductive stages, R1–R3
9
1. Tassel ears
Figure 1. (a) Complete replacement of tassel and (b–c) partial replacement of tassel on tillers in an end row. Images: (a) Osler Ortez, (b–c) Robert Nielsen.
2. Fasciated ears
Figure 2. Fasciated popcorn ear with seven ear branches. (a) Side and (b) top views. Images: Osler Ortez.
3. Pinched ears
Figure 3. Corn ears at different developmental stages. (a) Mature pinched ear due to sulfonylurea herbicide applied between V7 and V10 stages, (b) developing ear at the V9 stage, and (c) developing ear at V12 stage. Images adapted from Strachan (2010). Images: (a–b) Antonio Perdomo, (c) Stephen Strachan.4. Blunt ears
Figure 4. Blunt ears, beer-can ears, or stunted ears. (a) The similarity in kernel row number of a blunt ear compared with a normal ear, but with arrested ovule and kernel development. (b) Different degrees of arrested development in blunt ears. Images: (a) Robert Nielsen, (b) Peter Thomison.
5. Silk-balled ears
Figure 5. (a–b) Silk-balled ears or scrambled silks, silks growing in different directions trapped within the husk and (c) ears with various severity levels of damage. Images: Robert Nielsen.
6. Incomplete kernel set
Figure 6. (a) Ears displaying incomplete kernel set; and (b–c) silk-clipped ears, damage caused by insect clipping before or during pollination. Images: (a) Peter Thomison, (b) Robert Nielsen, (c) Osler Ortez.7. Banana ears
Figure 7. Banana ears exhibit curvature along the cob shape with different degrees of damage (A, B, C). Husk leaves were removed (if needed) for better symptom visibility. Images: Osler Ortez.
8. Zipper ears
Figure 8. (a) Zipper ears increase at higher seeding rates; from left to right (three ears per treatment): 62,000, 86,000, and 111,000 seeds per hectare. (b) Ear with several kernel rows missing due to pollination or abortion issues, husk leaves were removed for better symptom visibility. Images: (a) Peter Thomison, (b) Osler Ortez.
9. Tipped-back ears
Figure 9. Tipped-back ears with unfilled kernels towards the tip. (a) Ear with about 50% tipped back, (b) about 25% tipped-back, (c) about10% tipped-back, and (d) about 5% tipped back. Husk leaves were removed for tip-back visibility. Images: (a, b, and d) Osler Ortez, (c) Justin McMechan.To learn more about these and other abnormal ears, a literature review is summarized here: https://doi.org/10.1002/agj2.20986. For more resources, previous work in Ohio has a comprehensive summary available, Troubleshooting Abnormal Corn Ears: https://u.osu.edu/mastercorn/.
When it comes to abnormal ears, questions still need answers. However, with the knowledge available, abnormal ears can be seen as the result of an “expression triangle” where susceptible hybrids, conducive environmental conditions, and unfavorable management practices can result in abnormal ears. The crop’s exposure to unfavorable conditions can negatively affect ear formation and produce abnormal ears. Abnormal ears reduce yield and can reduce grain quality too.
References
Ortez, O. A., McMechan, A. J., Hoegemeyer, T., Ciampitti, I. A., Nielsen, R., Thomison, P. R., & Elmore, R. W. 2022a. Abnormal ear development in corn: A review. Agronomy Journal, 114, 1168– 1183. https://doi.org/10.1002/agj2.20986
Ortez, O. A., McMechan, A. J., Hoegemeyer, T., Ciampitti, I. A., Nielsen, R. L., Thomison, P., Abendroth, L. J., & Elmore, R. W. 2022b. Conditions potentially affecting corn ear formation, yield, and abnormal ears: A review. Crop, Forage & Turfgrass Management, 8, e20173. https://doi.org/10.1002/cft2.20173
Ortez, O. A., McMechan, A. J., Hoegemeyer, T., Rees, J., Jackson-Ziems, T., & Elmore, R. W. 2022c. Abnormal ear development in corn: A field survey. Agrosystems, Geosciences & Environment, 5:e20242. https://doi.org/10.1002/agg2.20242
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Lep Monitoring Update WBC Numbers Increase, Scouting Expands
Western Bean Cutworm
Western bean cutworm (WBC) averages have increased in many counties across Ohio from July 18 - 24. For the week ending July 24, the statewide average was greater than 9 moths, an increase from the 8 moth average last week. We recommend that any counties that reported an average of 7 or more moths within a week should begin scouting for egg masses. Over the past week 14 counties reported an average of 7 or more moths including: Ashtabula, Coshocton, Defiance, Erie, Fulton, Geauga, Hancock, Huron, Lucas, Paulding, Portage, Sandusky, Trumbull, and Williams (Figure 1).Western Bean Cutworm Moth Map
July 18 – 24, 2022
Scouting guidelines
1) Counties reporting an average of 7 or more moths within a week should scout for WBC egg masses (Figure 2).2) Randomly choose 20 consecutive plants in 5 locations within a field (a total of 100 plants per field).
2) Inspect the uppermost 3–4 leaves of the corn plant. It is helpful to look at the leaves with the sun behind them. Oftentimes the shadow of the egg mass will show through the leaf without having to examine the leaf closely.
3) Record the number of plants with egg masses or larvae to calculate the percentage of plants with WBC present.
For more scouting information, view our WBC scouting video https://aginsects.osu.edu/news/western-bean-cutworm-video
Treatment Recommendations
Field corn should be treated with a foliar treatment if more than 5% of inspected plants have eggs or larvae. Sweet corn should be treated if more than 4% of inspected plants have eggs or larvae (processing market), or 1% of plants (fresh-market). Timing an insecticide application is critical and must happen before the caterpillar enters the ear, but after the eggs hatch. If the eggs have hatched, applications should be made after 95% of the field has tassels. If the eggs have not hatched, monitor the egg masses for the color change. When the egg masses are first laid they are a whiteish color. As the egg masses mature, they turn a purplish color. Hatch will occur within 24–48 hours once eggs turn purple.
Corn Earworm
The number of Corn Earworm (CEW) numbers remain low but did slightly increase this past week. Brown county numbers increased from last week and overtook Van Wert County as the highest out of all monitoring counties with an average of 7 moths (Figure 3).Corn Earworm Moth Map
July 18 – 24, 2022
Fall Armyworm
Of the 5 counties that are monitoring Fall Armyworm (FAW), 4 counties have reported catching FAW the week of July 18 – 24, an increase from only 2 last week. Clark reported the most FAW with 4, an overall decrease from their 6 last week (Figure 4).Fall Armyworm moth map
July 18 – 24, 2022
European Corn Borer
This week’s numbers for European Corn Borer (ECB) have remained steady with no counties reporting of finding any ECB for the second week in a row (Figure 5).European Corn Borer Moth Map
July 18 - 24, 2022
Crop Observation and Recommendation Network
C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.
Contributors
Disclaimer
The information presented here, along with any trade names used, is supplied with the understanding that no discrimination is intended and no endorsement is made by Ohio State University Extension is implied. Although every attempt is made to produce information that is complete, timely, and accurate, the pesticide user bears responsibility of consulting the pesticide label and adhering to those directions.
CFAES provides research and related educational programs to clientele on a nondiscriminatory basis. For an accessible format of this publication, visit cfaes.osu.edu/accessibility.