FORT WAYNE, Ind. — Wheat may be the No. 3 grain crop in Ohio, but it is No. 1 when it comes to disease problems, an Ohio State University plant expert said.

“Wheat certainly does have more major disease problems,” said Pierce Paul, assistant professor in OSU’s department of plant pathology at the Ohio Agricultural Research and Development Center in Wooster, Ohio. “Wheat has some of the most important major disease problems.”

This past year’s wheat crop wasn’t bad, and disease problems have been spotty and not widespread, Paul said.

“More than anything, this is probably weather related,” he said. “The conditions just weren’t favorable for disease. We’ve also done a pretty good job of getting farmers to follow basic management guidelines to prevent major disease problems.”

Diseases such as Fusarium head blight and Stagonospora leaf blotch can cause problems in a variety of ways, Paul said.

Fusarium head blight, also known as head scab, is a fungal disease. The fungus produces a toxin that could harm animals, Paul said.

Stagonospora leaf blotch is a disease of the wheat head and can cause a substantial reduction in head weights, thus affecting yields and bushels per acre, he said.

Because weather affects diseases differently, farmers and experts never know what to expect in a given season.

“The types of diseases we see varies from year to year,” Paul said. “There’s no year when every disease is a problem. You’re usually likely to have one disease that is prominent. So much depends on the weather.”

This uncertainty means farmers should have a good overall management program, he said.

“There are parallels between managing weeds, disease and pests,” he said. “Of course, the approaches to managing each do vary, but it’s all pest management.”

Proper management includes using wheat varieties best able to ward off diseases that could cut into yields, and not planting wheat in fields where disease risk is higher, Greg Shaner, a Purdue University extension plant pathologist, said in a university news release.

“We’ve generally recommended not planting wheat into corn residue,” Shaner said. “What we’ve found is that if we have a spring where the weather is really favorable for scab, it doesn’t matter if you’ve got corn residue in the field, there’s enough of the fungus around. But if conditions are only marginally favorable for scab, it may be worse where you’ve got corn residue than where you don’t.

“The fungus that causes Fusarium head blight is the same one that causes Gibberella ear rot and stalk rot in corn,” he said. “Even if you don’t have an ear rot or stalk rot problem in a corn crop, that fungus is part of the group that decays corn residue. So you can pick up most any piece of corn residue and Gibberella fungus will be there.” Farmers should also be aware that the planting date can also be a factor in preventing disease, Shaner said.

Producers who wait to plant wheat until after the Hessian fly-free date in their area can lower the odds of transmission of the barley dwarf virus, he said. The Hessian fly-free date ranges from Sept. 22 in extreme northern Indiana to Oct. 9 in southern Indiana counties. Barley yellow dwarf virus, which causes yellow dwarf disease, is transmitted by aphids, Shaner said.

“If a wheat field is planted before the fly-free date, there’s a greater likelihood that aphids will still be active. The aphids will zero in on the little wheat plants that are just emerging. If the aphids are carrying the virus they will transmit the virus as they feed.”

This farm news was published in the Oct. 4, 2006 issue of Farm World, serving Indiana, Ohio, Illinois, Kentucky, Michigan and Tennessee.