Ohio's Wheat Facing Low Head Scab Risk

May 26, 2006

WOOSTER, Ohio – Ohio's wheat is so far facing a low risk of head scab, a serious disease that can impact yields and potentially produce contaminants that are harmful to humans and animals.

Pierce Paul, an Ohio State University plant pathologist with the Ohio Agricultural Research and Development Center, said that wheat throughout the state is either flowering or will begin flowering, a stage of development where the crop is most susceptible to head scab infections. However, temperatures have not been favorable for the development of the disease.

"Fungal spore counts are up because of recent rains, but temperatures have remained cool in the evenings. Warmer nighttime conditions are needed for head scab to be any kind of threat to the wheat crop," said Paul, who also holds a partial Ohio State University Extension appointment. "However, growers should still be on their guard for the head scab threat to increase. Conditions are calling for wam temperatures by next week."

Head scab or Fusarium head blight is a very significant disease, not only from yield loss, but also from 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 find the latest on head scab risk by logging on to the Fusarium Head Blight Prediction Center (http://www.wheatscab.psu.edu) -- an early warning system run jointly by OSU Extension, 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 overall, the wheat crop is in good condition. According to the Ohio Agricultural Statistics Service, Ohio's winter wheat is over 70 percent in good to excellent condition with over 40 percent headed.

"Despite a few patches of yellowing due to a variety of factors from viral infections to nitrogen deficiency, the wheat crop is still in good shape," said Paul. "Powdery mildew is still spreading, but growers can easily control that through fungicides."

Powdery mildew spreads during conditions of high humidity and is characterized by powdery white old growth on leaf surfaces. Growers are recommended to treat susceptible varieties for powdery mildew when the disease reaches the leaf right below the flag leaf and when 2 percent of the leaf is diseased (two to three lesions found). Fungicides such as Tilt and PropiMax should be applied before flowering to control the disease.

Author(s): 
Candace Pollock
Source(s): 
Pierce Paul