June 11, 2003 | By: Laura Skillman

Kentucky’s winter wheat harvest rapidly is approaching and this year’s wet, cool conditions have made for an environment conducive to plant growth but also to some disease development.

“This year’s wheat crop looks good,” said Lloyd Murdock, a University of Kentucky agronomist and member of the Wheat Science Group.

Murdock said wheat didn’t get off to the best start this past fall when many fields were planted late. But the crop grew well and the cool temperatures were good for kernel development.

“I think we will see some good yields,” he said.

Only one issue is affecting the quality of this year’s crop.

Fusarium head blight has made an appearance in many wheat fields across the commonwealth. However, the fungal disease, commonly called head scab, is not at severe levels in all fields, said Don Hershman, UK Extension plant pathologist.

“I suspect every field in the state has some Fusarium head blight but there is a wide range in how much disease is present,” he said. “Some fields have head blight incidence as high as 75 percent, while others are below 15 percent.”

The disease causes the kernels to shrivel lowering yield and weight.

Some varieties are showing greater damage than others. That is due, in part, to the environmental conditions at the time the crop was flowering, much of which is genetically based. Head scab is generally a problem when wet, especially warm, wet conditions occur during the flowering stage. This factor can help explain the difference in levels seen between fields, Hershman said.

Some fields escaped serious infection, while others flowered during disease-favorable conditions and got hammered by the disease, he said.

There are new varieties showing head scab resistance but it is too early to tell if these varieties also will yield better than susceptible varieties, Murdock said.

What effect the head scab will have on marketing wheat will depend on the amount of DON, also called vomitoxin, in the wheat crop. DON is a fungal toxin produced by the fungus as it is infecting and developing in the wheat heads. Excess DON can seriously impact a farmer’s ability to sell his crop in some markets. Many grain purchasers will not buy grain with a level above 4 parts per million and some have even more stringent requirements.

“There is no doubt in my mind that some farms will experience significant DON problems this year, but I do not believe it will be a uniform problem,” Hershman said.

Even healthy appearing kernels may be contaminated with DON, he said. The only way to know for sure is to have them tested.  By having their wheat tested, farmers will know their marketing options.

On a positive note, Hershman said some diseases that often cause yield losses such as leaf rust, powdery mildew, leaf and glume blotch and viral diseases, were at rather low levels this year and have not done much damage.


Lloyd Murdock, Don Hershman 270-365-7541