C.O.R.N. Newsletter: 2025-22
-
Corn Vomitoxin Management Critical Considerations at Tassel
Mycotoxins, specifically deoxynivalenol (DON), commonly referred to as vomitoxin, has become a significant problem for Ohio corn growers. What was once considered an every-ten-year problem, has now become a yearly challenge in some sections of the state. DON contamination of grain is associated with Gibberella ear rot (GER), a disease caused by the fungus Fusarium graminearum. The Ohio State University Cereal Pathology Lab led by Dr. Pierce Paul has been researching and developing weather-based models to predict when weather conditions are favorable for DON contamination of corn grain. The current models predict when conditions are favorable for grain to be contaminated with at least 1 ppm DON.
The fungus that produces DON primarily infects corn ears during pollination while silks are wet (R1 growth stage). While insect feeding later in the growing season can be a route of secondary infection, this is a lower risk than during silking.
Effective management of DON requires the combination of multiple strategies. A model prediction can help you determine if a fungicide for DON management would be beneficial. Of the many fungicides available for corn disease management, two are considered to be the most consistently effective at suppressing GER and DON. These two products are Proline 480 SC and Miravis Neo. They have shown the best results when applied when silks are still wet (early- to mid-R1). The fungicide must penetrate the canopy and reach the corn silks when they are still wet to be effective. Applications made after silks are dry and brown are considerably less effective at reducing DON, with research showing that by 11 days past full silk, DON levels were the same as when no fungicide was applied. With the variation this year in plant growth stages and some fields having replanted corn in patches, perfect timing may be hard to achieve. Your goal should be to apply fungicide when the majority of the field is silking but before the earliest silks turn brown. While not as effective as applying the fungicide during wet silk, the DON reduction is greater with a V18 application than a brown silk application.
When applying fungicides, using water-sensitive paper attached to the silks can help you determine if your application is reaching the silks. Our work on using fungicides for DON management has primarily been conducted using high-clearance sprayers, either with drops or a boom over the top of the plant. Our coverage on water-sensitive paper increased when we used 20 gallons per acre compared to 15 gallons per acre. Last year, we conducted our first research trial to evaluate the use of a drone for fungicide applications in DON management. However, weather conditions did not favor disease development, and all of our plots had low DON levels. There was no significant difference between application methods or fungicide treatments. The drone application had less coverage on the water-sensitive paper on the ear leaf than the ground application.
Hybrid resistance is crucial, even with fungicide application, in achieving low DON levels at harvest. A hybrid with partial resistance will have lower DON at harvest than a susceptible hybrid when both have received a fungicide application for DON management. Extended harvest periods allow more time for DON production, particularly if harvest is delayed by wet conditions. An additional tool is to scout fields that pollinate during high-risk times for GER and plan to harvest those fields early.
Throughout corn pollination this year, we will be updating the models and sharing estimates of the chance of grain in various parts of the state being contaminated with at least 1 ppm DON. This information will be made available through the C.O.R.N newsletter. Predictions generated by these models should only be applied to corn pollinating during the model’s prediction window, which is specific for each area of the state and field within that area. As a result, each week, predictions will likely change for the corn that is pollinating based on changes in weather conditions. Similarly, during any given week, predictions will likely change from one field to another based on hybrid maturity, hybrid resistance, planting date, and weather condition, all of which affect the silking/pollination window.
It is important to remember that weather conditions are only one part of the disease triangle, and that all three sides of the triangle are needed for disease development, and in this case, for DON contamination to occur. The other two sides of the disease triangle are a susceptible corn hybrid and fungal spores being present at the time and growth stage when weather conditions favor infection, disease development, and toxin production. Consequently, the actual level of DON contamination will vary from field to field, depending on the susceptibility of the hybrid planted, tillage, and crop rotation, as well as weather conditions. Under favorable weather conditions, a highly susceptible hybrid planted no-till into corn stubble will likely be contaminated with DON well above 1 ppm compared to a tilled field of a moderately resistant hybrid planted after beans.
DON model predictions are based on data from publicly available weather stations located at OSU-CFAES research farms and airports around the state. The two weather factors used to make predictions are temperature and relative humidity as number of hours within certain ranges or above certain thresholds. These factors can vary significantly over a few miles or with changes in elevation
The risk of DON contamination of grain, predicted using weather data from the ten CFAES weather stations, is low across the state for cornfields reaching the R1 growth stage. In other words, based on the prediction models, there is a very low chance of DON contamination of grain in fields in the vicinity of the weather stations that are now pollination being greater than 1 ppm. The current models were not developed to predict whether DON will be 2, 5, 8, or 10 ppm; they only predict whether DON will be ≥ 1 ppm, but not how much greater. Last year, the highly susceptible hybrids in the hybrid screening trial were over 1 ppm at all locations, as predicted by the model, while the hybrids with partial resistance under the unfavorable disease development conditions post-silk had DON levels of 0.1 ppm.
Use predictions as one piece of information to help guide your DON management decisions. You should also consider the susceptibility of your hybrid and production practices when making management decisions. The results of the 2023 and 2024 DON hybrid resistance screening trial can be found at http://go.osu.edu/vomitoxin . This site also contains results from other Corn DON research projects done at OSU. Again, when weather conditions are favorable as suggested/predicted by the models, fields of highly susceptible hybrid planted no-till after corn will likely yield grain with DON above 1 ppm compared to a tilled field of a moderately resistant hybrid planted after beans.
-
Have you registered for the August 20th Ditch the Runoff Field Day?
We are five weeks away from Ohio State University Extension’s Water Quality Team field day: Ditch the Runoff! This is their third annual conservation-focused field day. This year's event will showcase a newly completed two-stage ditch in Williams County, Ohio. Guest speakers will include Greg LaBarge (Ohio State Extension), Dr. Jim Uphaus (Rhodes State College), Manny Lay (Williams Soil and Water Conservation District), Justin McBride (Ohio Department of Agriculture) and Kevin Miller (Williams County Farmer) where they discuss benefits of conservation practices at the edge-of-field and in the pocketbook.
The field day will begin at 9:00 AM on Wednesday, August 20th, 2025, at 10117 CR 21, West Unity. The field day will wrap up at 12:00 PM with lunch to follow.
There is no charge to attend, thanks to sponsorship from Williams County Soil & Water Conservation District. Registration is required as space for this event is limited. Register at go.osu.edu/DTR2025. Email cochran.474@osu.edu or torlina.1@osu.edu with any questions.
-
How to Use the Crop Risk Tool
Unfortunately, there is no crystal ball that can reveal what impact disease will have on your farm. However, you can take advantage of the new web-based Crop Risk Tool hosted by the Crop Protection Network to assess disease risk.
The Crop Risk Tool forecasts the risk of multiple foliar diseases like tar spot and gray leaf spot in corn and white mold in soybean using validated disease models and site-specific weather data. Risk forecasts are updated daily based on recent weather conditions and a 7-day forecast is included to aid future decision-making
It will also soon include the vomitoxin risk forecast model being developed by the Ohio State University Cereal Pathology Lab thanks to support from the Ohio Corn Marketing Program.
Follow the steps below to use the Crop Risk Tool or view a step-by-step video at https://www.youtube.com/watch?v=xJ707vRQkjE.
Step 1: How to Access the Tool
To access, click on the green button “Access The Forecasting Tool” on the landing page https://cropprotectionnetwork.org/crop-disease-forecasting
Step 2: How to Set Up Location
Either zoom in and find the location you are interested in and drop a pin, or you can upload a prepopulated .csv file with GPS coordinates (latitude, longitude as decimal degrees in separate columns). Then click on the “Fetch Weather Data” button to retrieve GPS-specific weather conditions.
Step 3: Finding Probabilities of Risk
Select the appropriate crop and the included disease forecast models will be displayed on the righthand pane of the tool.
Step 4: Interpreting the Data
The Crop Risk Tool should only be used during periods when crops are susceptible to the disease. For example, only between growth stages V10 and R3 for corn foliar diseases. Also keep in mind that the pathogen must be present in the field along with a susceptible variety or hybrid for disease to occur.
In the example below, the forecast was restricted to the past week (July 3 – 10, 2025) and the 7-day forecast at the Northwest Agricultural Research Station in Wood County. Assuming the crops are at or past the V10 growth stage, the risk of tar spot is low, but extremely high for gray leaf spot. In this case, if corn is tasseling and/or silking and a susceptible hybrid was planted, a fungicide application should be considered to manage gray leaf spot.
The Crop Risk Tool is powered by the National Predictive Modeling Initiative of the USDA-ARS and was developed in collaboration with the University of Wisconsin-Madison Department of Entomology. Funding for individual crop disease forecasting tools was provided by the National Corn Growers Association, the North Central Soybean Research Program, and the United Soybean Board.
-
Reminder: Grain Handling Systems Open House!
Register today to secure your spot at the Molly Caren Ag Center Grain Facility for an open house to learn more about grain handling systems and safety. Technology and design will be on display July 24, 2025 from 11-2pm. OSU Extension and industry representatives will be on hand to discuss Millwright design and efficiencies, grain automation, harvest equipment, grain scale and software, and safety.
Two scheduled presentations offer a chance for CCA and pesticide continuing ed and recertification credits.
1-1:30 Vomitoxin Management (Comm. 2A and Private 1, CCA IPM)
1:30-2 Grain Bin Fumigation (Comm. 10C and Private 6, CCA IPM)
The event is FREE but an RSVP is required for lunch. Those who want credits will be charged $5 per session payable day of.
To see more details and RSVP by July 18 go to go.osu.edu/GrainOpenHouse.
The Molly Caren Ag Center grain facility is located 1 mile north of the Farm Science Review at 990 St. Rt. 38 NE, London, OH 43140.
-
The North American Manure Expo coming on July 30th and 31st in Wauseon, Ohio
The North American Manure Expo is coming to Wauseon Ohio on July 30th and 31st at the Fulton County Fairgrounds. This event will showcase research, innovation, and solutions found within manure management. The event brings manure haulers, applicators, brokers, nutrient management specialists, researchers, producers, manufacturers, custom operators and extension personnel together for two days of learning, networking and evaluation of new technology, research, equipment and opportunities. Over the two days we have tours, an industry trade show, live solid and liquid manure demonstrations and educational sessions.
The first morning of the Expo is dedicated to tours that showcase innovative manure solutions. Attendees can purchase tickets on-line or there may be room for walkups to one of the four tours:
Tour #1: Andre Farms & Stuckey Farms – visit one of Ohio’s largest Class II EPA composting facilities followed by a beef and grain operation that will showcase how they have gotten more out of compost through a variety of projects.
Tour #2: Bridgewater Dairy – see how this farm is leading the way in manure management and renewable energy. Tour guests will see their new methane digester, manure irrigation system and manure pipeline, followed by hearing about their long-term approach to sustainability.
Tour #3: Precision manure irrigation – See the Rain360 irrigation system in action. Farmers and experts will cover the system’s real-world performance, economic benefits and environmental advantages.
Tour #4: Seiler Farms – This tour will showcase innovative water management practices including a two-stage ditch, a proven method for improving drainage, reducing nutrient runoff and enhancing water quality. See how they protect water resources while maintaining crop production.
Day one also includes manure pond agitation demonstrations with boats and sticks at a nearby dairy farm, manure separation demos, rapid manure transfer from tankers to frac tanks demonstrations, confined space safety training and the always popular pressurized hose release safety demonstration.
Day two of the Expo kicks off with 16 educational sessions in the morning. These are followed by both solid and liquid manure tanker and drag hose application demonstrations and a manure spill containment and stream water restoration demonstration.
Exhibitors will have booths in the trade show both days featuring new and manure innovative technology so you can visit and learn from these equipment makers. Puck will once again have their always-well-attended pump school.
Attendees can register online or just show up. For the full schedule, information on the educational sessions, registration information and to purchase tour tickets, visit ManureExpo.com.
-
NE Ohio Hay Day Hosted by OSU Extension and Norden MFG
Join OSU Extension and Norden MFG on August 2, 2025, for the NE Ohio Hay Day. Held at Norden MFG, 4210 Kinsman Rd NW, North Bloomfield Ohio 44450. The program will start at 10:00 AM and will conclude at 1:00 PM. This program is free thanks to generous support from Norden MFG, the Trumbull County Holstein Club, and the Hertzer Family Trust.
Making quality hay during the summer of 2025 has been a challenge and the use of hay preservatives may be of value with tight weather windows. OSU Forage Specialist Dr. Emma Matchem will join us to discuss the benefits and concerns with using a preservative in your forage. Horses can be the pickiest customers of hay, and Amanda Barnum, OSU Extension Educator Ashtabula County, will discuss the nutritional requirements of horses to help tailor your forage harvest to meet their needs. Lee Beers, OSU Extension Educator Trumbull County, will discuss nutrient management strategies to promote higher quality forage and increase your yield per acre. There is an increased risk of having hay spoilage with weather conditions this summer. Les Ober, OSU Extension Educator Geauga County, will discuss strategies to prevent spoilage in the field and in the barn. Rounding out the morning session will be How to Test Hay for Nutrient Value.
One of the front runners in hay making technology is Norden Manufacturing and we are fortunate to be able to hold this program at their home location. In the afternoon the staff from Norden will demonstrate their latest hay making equipment. Field operation will be weather dependent.
The program includes lunch sponsored by the Trumbull County Holstein Club. Pre-registration is required by July 30th to reserve your lunch. You can register online at http://go.osu.edu/neohiohayday or call OSU Extension Trumbull County at 330-638-6783.
-
Battle for the Belt: Season 3, Episode 16 – Tar Spot in Corn
Season 3, Episode 16 of Battle for the Belt is now available: https://www.youtube.com/watch?v=QIx3GTm5L44
In Episode 16, Dr. Stephanie Karhoff, Ohio State University Extension Agronomic Systems Field Specialist, discusses tar spot symptoms and scouting techniques.
Tar spot is a relatively new disease in Ohio, first appearing in 2018. Pathologists and agronomists are still researching tar spot to understand which environments favor this disease. This year, OSU Extension on farm research network, eFields, is conducting a scouting survey called the “Tar Spot Surveillance Survey” to further explore optimal environments for tar spot infection to improve management of this disease in Ohio. County Extension Educators across the state are scouting three corn fields in their county weekly, starting at the V7 growth stage to report tar spot infection. Field management information is collected to identify if there are any management practices that correlate with tar spot occurrence. Towards the end of the season, disease incidence (number of plants with disease) and severity (percent of leaf covered by disease) will be evaluated in the fields that have tar spot. Look for results and more information on this study in the 2025 eFields report!If you are out in your corn fields in the next couple of weeks scouting for tar spot, look for small, raised bumps that look like flecks of tar on the leaf. The black spots are stromata that are embedded into the leaf surface. This means that tar spot stromata cannot be scratched off. Insect frass is often mistaken for tar spot but is easily scratched or wiped off (Figure 1). While scouting, if you think you have come across tar spot, wet your finger and try to rub off the black spot, and if it comes off, then it is not tar spot.
Though tar spot is prevalent throughout Ohio, if you detect tar spot in your field, please contact your local county educator to assist Ohio State Extension in tracking when and where tar spot is occurring and the impact of this important disease.
Crop Progress Updates from the Field
Corn at the Western Agricultural Research Station reached R1 (silking) in the first planting date (4/18). As of now, this is the only location that entered the reproductive stage of corn. Because we have four different hybrids, disease resistance varies. The 100-day hybrid tends to show disease symptomology first.
Low levels of gray leaf spot were seen on the ear leaf of the 100-day hybrid, but the more resistant hybrids showed no disease (Figure 2). In disease management, the ear leaf is the most important to protect, so when scouting, it is imperative to note what leaf the disease is on. The first planting date of soybean reached R3 (beginning pod) and the only present disease in soybean has been 
Septoria brown spot, which is not normally a yield limiting disease in Ohio. Much of Western and Northwest Ohio are in need of the rain as corn was showing signs of stress with rolling leaves. The rest of the stages for this location are presented in Table 1.Corn at the Northwest and Wooster locations are in vegetative stages. Soybean are in the R3 and R2 stage at Northwest and Wooster, respectively (Figure 3). These two locations are without disease, in the earliest planted soybeans. The dry weather is not conducive for frogeye leafspot, which is our main foliar disease concern.
Table 1. 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
(July 7 - July 13)
2-inch soil temperature 
(July 7 - July 13)Air Temperature
(July 7 - July 13)
Planting dates
GDDs
(Cumulative)
Corn  
Growth 
StageSoybean Growth 
StageWestern,
Clark County
1.37
Min: 77°F
Max: 87°F
Mean: 80°F
Min: 68°F
Max: 92°F
Mean: 78°F
April 18
May 12
May 27
June 13
June 24
1559
1300
1124
840
556
R1
V13
V10
V6
V4
R3
R2
R1
V4
V1
Wooster,
Wayne County
1.39
Min: 74°F
Max: 81°F
Mean: 77°F
Min: 59°F
Max: 89°F
Mean: 75°F
March 27
April 18
May 12
June 2
June 23
1385
1325
1130
956
546
V14
V13
V10
V7
V3
R2
R2
V7
V4
VC
Northwest,
Wood County0.24
Min: 69°F
Max: 89°F
Mean: 78°F
Min: 60°F
Max: 91°F
Mean: 77°F
March 27
Apr. 16/17
May 12
May 29
June 24
1541
1492
1274
1096
576
V14
V13
V10
V7
V3
R3
R3
R2
V5
VC
Follow the Battle for the Belt campaign all season long to stay informed and up to date.
Catch every episode on the Ohio State Agronomy YouTube channel. Ohio State Agronomy -
Lep Monitoring Network – Western Bean Cutworm numbers are on the rise #12
This is our 12th week of monitoring moth pests in Ohio. Between July 7th and July 13th, we continued to monitor Corn Earworm (CEW) and Western Bean Cutworm (WBC). Over the past week, the state of Ohio experienced mild rainfall and average temperatures (75.9 °F), which may have led to an increase in WBC activity. The statewide averages for CEW remained low. Please read below for more details.
Western Bean Cutworm
This week 21 counties monitored WBC (Figure 2) with a total of 56 traps. Nineteen counties trapped WBC this week, which is an increase from the previous week. Moth counts were greater than what we have seen so far this season, and the average moths per county was 5.40. Counties with the highest averages included Sandusky (25.0), Lucas (16.0), Defiance (13.8), Fulton (13.7), Henry (10.3), and Wayne (7.5) (Figure 2). The numbers for WBC are expected to remain high, so counties with an average greater than 7.0 moths should consider inspecting their fields.
How to scout for WBC egg masses
A field of corn that is in the process of forming tassels is an ideal place to start looking for WBC eggs. Examine 20 plants in 5 different locations (100 plants total). Typically, eggs can be found on the underside of upright leaves near the tassel or on the upper side of leaves near the leaf collar. Newly laid eggs are usually a whitish color, and the older eggs can be dark purple (Figure 1). Treatment options should be considered if 5% of plants have egg masses. For optimal results, treatment should be applied when the majority of the eggs found are purple.To view a more detailed video on scouting – click here: https://youtu.be/qGjpwtfkObM?si=CFPzX1rlqt6jzyJw
For more information on how to scout WBC please visit: Western Bean Cutworm | Ohioline
Western Bean Cutworm Moth Map
Week #6
July 7th to July 13th, 2025
Corn Earworm
This week we monitored 35 traps in 16 counties across Ohio. Similar to last week, there were low numbers of CEW (Figure 4) across the state with an average of 0.44 moths per county (Figure 4). Morgan County had the highest moth average, which was 2. Overall, the statewide averages of CEW have remained low since the beginning of June.
More information on CEW can be found here: Corn Earworm in Field Corn; Watch for Molds | Agronomic Crops Network
Corn Earworm Moth Map
Week #6
July 7th to July 13th, 2025
-
Statewide Slug Monitoring Project – Update #9
Our ninth (and final) slug update for the season and it covers monitoring from July 7th to July 13th. During this time, there were 6 counties that monitored a total of 36 shingle traps. Slug counts were similar to last week, and the average slug count per county was 0.8. The highest average slug count was 4.6 slugs in Seneca County, which has had higher slug averages in the past weeks. Slug shingle monitoring ranged over 9 weeks (3 weeks before plant and 6 weeks after plant). The majority of the monitoring counties have completed the monitoring period, so we will no longer be giving weekly slug updates. Slug shingle monitoring in Ohio is funded by the United Soybean Board.
Slugs in Ohio Week #9
July 7th – July 13th, 2025
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.