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College of Food, Agricultural, and Environmental Sciences


Ohio Wheat Could Be at Risk for Head Scab, if Rain Coincides with Flowering

May 20, 2009

WOOSTER, Ohio -- Ohio wheat could be facing a risk of head scab if any rain, coupled with warm temperatures, coincides with crop flowering.

"Flowering is the growth stage where wheat is most susceptible to head scab infection," said Pierce Paul, an Ohio State University plant pathologist with the Ohio Agricultural Research and Development Center. "We expect wheat to be flowering mid to late this week or early next week, and if it rains during that time, we might have a high risk of head scab development."

Head scab or Fusarium head blight is a very significant disease, not only because it causes yield loss, but also because contaminants associated with the disease called mycotoxins that pose a health threat to humans and animals. The effects of the disease can impact growers, millers, bakers and consumers. Growers who plant wheat into corn residue are more at risk for head scab infection because the fungus can survive in the corn residue and then easily spread to wheat if weather situations are right.

Growers can follow the latest on head scab risk by logging on to the Fusarium Head Blight Prediction Center ( -- an early warning system run jointly by Ohio State University, Penn State University, Purdue University, North Dakota State University, South Dakota State University and the U.S. Wheat and Barley Scab Initiative. The system uses the flowering dates of wheat and weather data to predict the risk of head scab in wheat fields throughout the growing season for 23 states.

Paul said that Ohio growers have been expressing concern because of the rainy conditions they have experienced over the past few weeks.

"Don't get overly excited, just be vigilant. Keep your eyes on weather conditions as we approach flowering and keep track of your growth stage, and look at scab forecasting system for whether there will be a risk of scab or not," said Paul, who also holds an Ohio State University Extension appointment. "If it gets dry over the next week and a half, the risk will be very low."

If high risk is imminent, growers can suppress head scab by applying fungicides at the time of flowering. Proline, Prosaro and Caramba fungicides are the most effective fungicides against head scab, said Paul. However, they will not provide 100 percent control.

"Efficacy against head scab varies and tends to be between 50 percent to 55 percent on average," said Paul. "Fungicide efficacy against vomitoxin is also very variable, ranging from 40 percent to 45 percent for the top three fungicides."

According to the Ohio Agricultural Statistics Service, 70 percent of Ohio's wheat crop is in good to excellent condition.

"The wheat crop is looking great, which is another reason why we hope head scab risk remains at a minimum," said Paul. "If we don't have disease problems and the weather is cool during grain fill, we might have a bumper crop."

Ohio wheat growers produce some of the highest quality soft red winter wheat sought after by millers and bakers in the nation. Ohio's wheat production brings in over $250 million to the state's agricultural industry, according to the Ohio Department of Agriculture.

Candace Pollock
Pierce Paul