Head scab on wheat.
Head scab on wheat.

Wheat growers across Ohio whose plants are at or near the flowering growth stage are at a moderate to high risk for Fusarium head blight development, said a wheat expert from the College of Food, Agricultural, and Environmental Sciences at The Ohio State University.

The concern is highest for growers in northwest Ohio for development of Fusarium head blight in wheat, also called head scab, said Pierce Paul, an Ohio State University Extension wheat specialist.

The wet, humid conditions experienced recently across the region are cause for concern for scab development on wheat at or near the flowering stage this week, said Paul, who is also a plant pathologist with the Ohio Agricultural Research and Development Center. 

OSU Extension and OARDC are the outreach and research arms, respectively, of the college. 

“Over the last three days (June 6, 7, and 8), the risk for scab development has changed from moderate to high,” he said. “This is a sustained moderate-high risk.

“While most of our fields are now in early grain fill, there are still a few fields in the northwestern portion of the state that are flowering this week. Fields flowering this week are still at risk for scab and vomitoxin because the region has experienced increased warm and humid conditions.”

This information is gleaned using a regional online assessment tool to determine head scab development risk. The Fusarium Risk Assessment Tool — available at the Fusarium Head Blight Prediction Center website, wheatscab.psu.edu — helps growers assess the risk for scab and to determine whether a fungicide application at flowering is warranted for scab control, Paul said.

Head scab is of concern for growers during flowering, which is when wheat heads are most susceptible to the scab fungus and infection is favored by warm, wet or humid conditions, Paul said.

Growers with wheat at or near flowering stage can minimize the risk of scab development by applying fungicides to their crops. While the ideal time to apply these fungicides is at flowering, applications made up to 5 days after flowering may also provide good levels of scab and vomitoxin control, he said.

“Wheat growers can consider putting on Prosaro at 6.5 ounces or Caramba at 14 ounces, and use a surfactant,” Paul said. “Our research has shown that you can get good scab control if fields are treated up to 5 days after flowering and that both fungicides are rainfast within an hour after application, if a surfactant is used.”

Scab is the most economically important wheat disease in Ohio because it affects the crop in multiple ways, Paul said. Scab can cause vomitoxin contamination of the grain, making it unfit for marketing and for human or animal consumption.