C.O.R.N. Newsletter: 2025-20
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Soil Crusting and Herbicide Carryover
Recent weather extremes have created favorable conditions for soil crusting and herbicide carryover, two separate phenomena that can cause poor early stand development in agronomic crops. The agronomic crops team has received several questions about how soil crusting and herbicide carryover might be impacting early crop performance, so this article is intended to review these issues in the context of recent conditions in Ohio.
Soil Crusting
Soil crusting is a hard, compacted layer of surface soil that forms under wet, warm conditions like what we’ve seen in many parts of Ohio these last few weeks. Soil crusts form when heavy rainfall detaches soil particles that are cemented together when the soil dries. Soil crusting inhibits seedling emergence, especially for broadleaf crops like soybean, reduces water infiltration, and increases runoff and erosion. Fine-textured soils (high silt and clay content) with low organic matter and frequent tillage have the highest risk of crusting.
Dr. Laura Lindsey and Dr. Osler Ortez address the agronomic implications of soil crusting and replanting decisions in this CORN Newsletter article from 2022.
Herbicide Carryover
Herbicide carryover refers to crop injury that occurs when an herbicide applied to a previous crop remains in the soil at a high enough concentration to damage the current crop. Each herbicide active ingredient has a different period that it will remain active in the soil, ranging from not at all to several months or years under the right conditions. The duration of carryover is determined by a combination of the active ingredient’s chemical structure and environmental conditions that affect how quickly the herbicide is degraded by chemical or microbial processes. Each herbicide label will indicate plant-back intervals for sensitive crops that represent how long it typically takes for various application rates of that herbicide to break down to safe concentrations under “normal” environmental conditions. Note that there are several factors that can extend these intervals, including the rate applied, soil characteristics (high pH, finer texture, low organic matter), and weather. Generally, degradation is sped up under warm, wet conditions and slows when it is either cold or dry. Last summer’s drought during the warmest months of the year and cool temperatures this spring likely slowed microbial degradation of herbicides, so the risk of herbicide carryover is probably higher now than in recent years. Herbicides with longer carryover periods to be aware of include atrazine (Aatrex), metribuzin (Sencor), clopyralid (Stinger), chlorimuron (Classic), fomesafen (Reflex), mesotrione (Callisto), imazethapyr (Pursuit), clomazone (Command), and pre-mixes containing these active ingredients. Consult each herbicide label to determine plant-back intervals for these products, including any additional precautions based on soil and weather conditions, and refer to last year’s spray logs to determine whether enough time has passed to safely plant a sensitive crop. If you are concerned about carryover in a particular field, you can conduct a bioassay with the soil and crop you are concerned about using the methods outlined in this article by Dr. Eric Jones (South Dakota State University Extension).
How Soil Crusting and Herbicide Carryover Might Interact
There are a few ways that soil crusting might interact with herbicides to increase carryover risk or otherwise interfere with herbicide efficacy:
- Pushing through a soil crust is stressful for seedlings and also delays emergence, potentially causing increased herbicide uptake that may exceed a crop’s tolerance. The combined stress of both pushing through a soil crust and herbicide carryover may also add up to increased seedling injury and reduced stand count, even if herbicides have had time to break down and residual concentrations are relatively low.
- Soil erosion that occurs alongside crusting can carry herbicides attached to soil particles and cause them to accumulate at higher concentrations in low spots in a field, increasing the risk of carryover damage. This damage would be patchy and may be indistinguishable from issues caused by waterlogging alone.
- Soil crusting may cause residual herbicides applied this year to remain on top of the soil surface, where they have limited contact with germinating weed seeds and are prone to being washed off during the next rainfall.
It may be hard to determine what exactly causes seedling injury and poor stands, as there are several other factors, including diseases, cold/wet soils, and planting issues that might also interact with and add to problems caused by crusting or carryover. If you do decide that replanting is necessary, light tillage before replanting would break up a soil crust and disperse any remaining herbicide carryover if weather allows, and it makes sense for your cropping system.
As a last note, we’ve also received a few questions about what the best residual herbicides are for the current wet conditions. Dr. Amit Jhala provides a great overview of this topic in this article from UN-L Extension.
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Lep Monitoring Network – Corn Earworm and Western Bean Cutworm # 10
This is our 10th week of monitoring moth pests in Ohio, and we are in our fourth week of monitoring Corn Earworm (CEW) and Western Bean Cutworm (WBC). Monitoring is reported for June 23 through 29, and during this time, we had a heat wave in most of Ohio. Despite the break in rain and increased temperatures, low moth numbers for CEW and WBC were reported. Please read below for more details.
Corn Earworm
Similar to last week, there were low numbers of CEWs in the majority of reporting counties. Morgan and Van Wert were the only counties to collect moths. Morgan County collected the most moths on average (6.7 moths). Overall, the statewide averages of CEW have remained low since the beginning of June.
More information on CEW can be found here:
https://agcrops.osu.edu/newsletter/corn-newsletter/2019-27/corn-earworm-field-corn-watch-molds
Corn Earworm Moth Map
Week #4
June 23rd to June 29th, 2025
Western Bean Cutworm
We are still in the early stages of monitoring for WBC, and we do not expect a peak until early to mid-July. This week 10 counties monitored WBC, and the majority of counties reported 0 moths. Three counties trapped WBC (Van Wert, Morgan, and Wayne.) The numbers decreased from last week, but the number of moths should increase by mid-July.
For more information on how to scout WBC please visit: Western Bean Cutworm | Ohioline
Western Bean Cutworm Moth Map
Week #4
June 23rd to June 29th, 2025
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Statewide Slug Monitoring Project – Update # 7
Our seventh slug update covers monitoring from June 23rd to June 29th. During this time, we had 10 counties monitoring a total of 66 shingle traps. After this hot, sunny week, our slug counts have decreased. The highest average slug count in a county was 2.2 (down from 8 last week), which was an outlier from the statewide average of 0.71 slugs per trap. We will continue to update slug numbers as the season continues, so stay tuned for slug updates over the next few weeks! Slug shingle monitoring in Ohio is funded by the United Soybean Board.
Slugs in Ohio
Week 7
June 23rd – June 29th, 2025
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Battle for the Belt: Season 3, Episode 14: Corn Disease
In Episode 14, we talked with Dr. Pierce Paul, Professor and Chair of the Department of Plant Pathology and State Extension Specialist for Cereal Crop Pathology. We discussed common diseases in corn, ear rots, vomitoxin, and crop disease forecasting tools.
Season 3, Episode 14 of Battle for the Belt is now available: https://www.youtube.com/watch?v=OF9Zqn32qe8
As a recap, in Battle of the Belt and the new Replanting trials, we are evaluating five planting date windows: Ultra early (late March to early April), Early (mid to late April), Normal (early to mid-May), Late (late May-first week of June), and very late (mid to late June). Additionally, we are evaluating contrasting seeding rates and relative maturities in corn.
What are the potential impacts of planting date and seeding rate on corn disease development?
Altering planting date and seeding rate can greatly influence the conditions that favor corn diseases. For example, higher seeding rates create denser canopies, leading to increased humidity within the crop. This will create an ideal environment for many foliar diseases to thrive. Similarly, later planting dates may align the crop’s most susceptible growth stages with mid-to-late summer conditions that are favorable for pathogens like gray leaf spot and tar spot.
“It’s not just about maximizing yield,” Dr. Paul notes. “You also have to consider what environmental conditions your planting decisions may create – and whether they may promote more disease.”
When discussing plant diseases, we often hear the terms severity and incidence. Can you briefly describe what these terms mean?
When scouting fields, it is very important to distinguish between incidence and severity. Incidence tells us how many plants are affected by a disease. For example, if 10 out of 50 plants show disease symptoms, this would be described as 20% disease incidence. Severity tells you how much each plant is affected. As an example, if assessing the ear leaf, and half of the leaf is covered in lesions, we would consider this to be 50% severity (Figure 1). Severity is often a better predictor of yield loss, while incidence tells us how widespread the disease is across a field.
What are the most common diseases we see affecting corn here in Ohio?
The top corn diseases to watch out for in Ohio include:
- Gray Leaf Spot – consistently prevalent across the state.
- Northern Corn Leaf Blight – weather dependent.
- Tar Spot – growing concern, especially in Northwest Ohio.
- Rusts – common and southern rust, more likely in southern regions.
- Ear Rots – including Gibberella and Fusarium ear rots, which can lead to grain contamination with mycotoxins.
Several ear rots will lead to the production of mycotoxins. What are some of those mycotoxins, and discuss why they could potentially lead to further issues post-harvest?
Some ear rot diseases produce mycotoxins, which can be harmful to livestock and reduce grain marketability. Key toxins in Ohio include:
- Deoxynivalenol (DON) or “vomitoxin” – causes feed refusal and performance issues in swine.
- Zearalenone – mimics estrogen and disrupts animal reproduction.
- Fumonisins – a concern for horse health.
- Aflatoxins – produced under drought-like conditions, can be a threat to human and animal health.
These contaminants pose challenges both on-farm and during grain marketing. Awareness and management are key.
When should farmers consider applying fungicides, and how do they determine the optimal timing?
Fungicide timing depends on disease pressure, hybrid susceptibility, and weather conditions. In high-risk situations – wet years, delayed planting, or disease history in the field there are a few recommended management strategies:
- Targeting application at the R1 stage (silking) for most foliar diseases.
- Selecting products based on the primary diseases of concern.
- Considering whether your hybrid is susceptible or resistant.
Fields near woods or rivers also tend to have higher disease pressure and may benefit more from fungicide applications.
What are disease forecasting models, and how can they be utilized to our benefit?
Disease forecasting models use weather data to estimate the risk of certain diseases developing. There are models available on the Crop Protection Network for gray leaf spot and tar spot, with additional tools in development for vomitoxin risk assessment.
Models can help you decide whether a fungicide application is worth the investment. These tools look at weather conditions leading up to key growth stages and calculate the risk of disease development or grain contamination with mycotoxins (forthcoming).
Resources Available for Further Reference
- Crop Protection Network (CPN) – Fungicide Efficacy for Control of Corn Foliar Diseases: https://cropprotectionnetwork.s3.amazonaws.com/corn-foliar-efficacy-2025.pdf
- Ohio State University Extension Corn Disease Fact Sheets – Printable guides to help identify and manage common foliar and ear diseases: https://ohioline.osu.edu/topic/ag-crops-and-livestock
- Corn Disease Forecasting Models – Real-time disease risk assessments. Available through the crop protection network. https://cropprotectionnetwork.org/crop-disease-forecasting
- Contact an OSU Extension Specialist – Reach out to your local Extension educator, field specialist, or crop pathology expert for field-specific recommendations: https://extension.osu.edu/directory/?f%5B0%5D=sm_field_ext_program_area%3Aagnr
Field & Crop Progress Updates
Planting is complete! Last week, the soil dried out and was adequate for planting across many locations in Ohio, including our three research stations. This resulted in all three locations planting the fifth and final planting date for the study (Table 1).
Table 1. Planting date, soil, and air temperature conditions for the fifth day of planting at the Northwest Station, the Western Station, and the Wooster Campus. The soil and air temperature data were retrieved from https://weather.cfaes.osu.edu/; reported as average temperatures. Location
2-Inch Soil Temp
Air Temp
Date
Northwest Agric. Research Station, Wood County
80°F
85°F
6/24
Western Agric. Research Station, Clark County
82°F
85°F
6/24
Wooster Campus, Wayne County
78°F
82°F
6/23
Across all planting dates, both corn and soybeans are progressing well with the extended period of heat the state has seen recently. Planting date one soybean at each location has entered the reproductive stages and is now presenting flowers (Figure 2). Corn from planting date one is currently at the V9 to V10 growth stage, entering a period of rapid growth and biomass accumulation.At the Northwest location, soybean planting dates one and two are at the R2 and R1 stages, while planting dates three and four remain in the V4 and V2 vegetative stages. Corn growth stages from planting dates one through four at this site are V9, V8, V6, and V4, respectively.
The Western and Wooster locations are seeing similar growth stages for both crops; specific stages by planting date are summarized in Table 2.
Table 2. Precipitation, soil temperature, average air temperature, and cumulative GDDs at the Western Agricultural Research Station, the Northwest Agricultural Research Station, and Wooster Campus. Weather data retrieved from: https://weather.cfaes.osu.edu/. Location
Precipitation, Inches
(June 23 - June 29)
2-inch soil temperature
(June 23 - June 29)Air Temperature
(June 23 - June 29)
Planting dates
GDDs
(Cumulative)
Corn
Growth
StageSoybean Growth
StageWestern,
Clark County
1.5
Min: 79°F
Max: 82°F
Mean: 81°F
Min: 76°F
Max: 85°F
Mean: 80°F
April 18
May 12
May 27
June 13
1176
917
740
456
V10
V8
V6
V2
R2
V5
V2
VC
Wooster,
Wayne County
0.39
Min: 78°F
Max: 79°F
Mean: 78°F
Min: 76°F
Max: 82°F
Mean: 78°F
March 27
April 18
May 12
June 2
1035
975
780
606
V9
V9
V7
V4
R1
V7
V4
V2
Northwest,
Wood County0.04
Min: 79°F
Max: 81°F
Mean: 80°F
Min: 79°F
Max: 85°F
Mean: 83°F
March 27
Apr. 16/17
May 12
May 29
1124
1076
857
680
V9
V8
V6
V4
R2
R1
V4
V2
Keep following the ‘Battle for the Belt’ this growing season to learn more and get further updates! You can find the full video playlist of Battle for the Belt on the Ohio State Agronomy YouTube channel.
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Hampered Hay Days & Hope for a Good One
“Hello, Mother Nature? Are you there? Am I coming in clear? I’d like to request a few hay days, please.”
Does this sound familiar? If you have been putting in calls to Mother Nature and prayers to the heavens for better hay-making weather, you certainly are not alone. My, what a ride it has been from June 2024 to June 2025. From extreme drought to excessive rain, we’ve been on a pendulum swing of weather conditions that seem to be working against the process of making high-quality hay.
While we can’t control the weather, there are many things we can influence when it comes time to put up hay. Many of these factors have to do with good maintenance of the land, our machinery, and our time. Some of these include:
- Staying on track with soil fertility through soil tests, tracking hay removal, and making fertilizer and/or lime applications.
- Introducing forages with improved genetic traits.
- Keeping tabs on damaging weeds and working to control them.
- Performing routine inspections and maintenance on machinery before putting it to work.
- Ordering spare parts that would be critical to have on hand if a machine goes down.
- Preparing a space to store hay under cover or under wrap until feeding time.
- Lining up hay buyers who can pick up hay from the field to avoid needing hay storage.
- Booking on-call helps in advance to assist when the conditions allow for field work.
- Prepare for flexible scheduling during hay season and have a backup plan to work around rigid commitments.
- Being a good neighbor by investing in kindness upfront, so that when the time comes that you need help, you have someone close to call in case you get into a sticky situation.
If you are struggling with any of the factors on this list, want to get better at them, or have your own tips to add, OSU Extension has an opportunity for you:
Join us on Friday, July 18, 2025, for Southeastern Ohio Hay Day! (Check out the official registration flyer here)
OSU Extension and a team of exhibitors and sponsors will be offering a day full of inspiration and socialization for anyone in the pasture management and haymaking businesses. Southeastern Ohio Hay Day will highlight the latest in hay-making equipment with displays and hay-making demonstrations from several manufacturers and associated dealers across the region.
Generous sponsorship of this event has been contributed thus far by the following entities:
- The Ohio State University Extension Noble, Athens, Belmont, Gallia, Guernsey, Monroe, Morgan, Muskingum, Perry, & Washington Counties
- The Ohio State University Eastern Agricultural Research Station
- D & J Sales and Service of Cadiz, OH
- Baker & Sons Equipment Company of Lewisville, OH
- Ag Pro of Zanesville, OH
- Lashley Tractor Sales of Quaker City, OH
- Foltz Ag Enterprises of Lancaster, OH
- Ohio Forage and Grasslands Council
- Ohio Sheep Improvement Association
- Noble County Soil and Water Conservation District
Registration will open and the tradeshow will begin at 9:00 a.m. at 16870 Bond Ridge Road, Caldwell, OH 43724. There will be ample opportunities for attendees to visit with dealer representatives and their peers during the event. Multiple educational talks will be conducted throughout the day by OSU Extension professionals. The event will conclude by 4 p.m. Southeastern Ohio Hay Day is free to attend and open to all. Light morning refreshments, lunch, and beverages will be provided.
To RSVP, visit https://go.osu.edu/haydayrsvp and complete the online registration survey. You can also call 740-732-5681 or email gelley.2@osu.edu to RSVP. RSVPs are appreciated by July 15, especially if dietary or accessibility accommodations are needed, but walk-in attendance will also be welcomed.
To view the most current event schedule, exhibitor list, or to print a flyer, please visit https://go.osu.edu/seohhayday for updates.
Exhibitor space is still available at Southeastern Ohio Hay Day. Contact Christine Gelley at gelley.2@osu.edu if you are interested in attending in this capacity, and a sponsor packet will be provided to you.
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.