September 08, 2008

LINCOLN, Neb. — Nebraska wheat growers can help protect next year's crop from wheat scab by taking precautions this fall, a University of Nebraska-Lincoln plant pathologist said.

Wet weather before and during wheat flowering this spring left Nebraska wheat growers having to deal with wheat scab, or fusarium head blight, said Stephen Wegulo, UNL Extension plant pathologist.

This is the second year in a row wheat growers have dealt with wheat scab, Wegulo said.

"And again, both south central and eastern Nebraska are the most affected," he said.

Scab causes low yield, poor quality grain, lower prices at the elevator due to the toxin scab produces – deoxynivalenol (DON, or vomitoxin) – in affected grain, and low germination and seedling blights if the grain is used as seed.

To deal with wheat scab, follow these strategies:

– Plant certified, fungicide-treated wheat seed this fall. If scab-affected grain must be used as seed, thoroughly clean it to remove scabby grain and treat it with a fungicide. Treating with a fungicide will increase germination and prevent or reduce seedling blights caused by the scab fungus, but it will not stop scab from developing on wheat heads the following spring.

– Don't plant wheat after corn or wheat. The scab fungus survives mainly on corn and wheat residue, but it also can survive on other grasses. While planting wheat after corn or wheat may not necessarily result in scab, if the disease were to occur due to favorable environmental conditions the damage likely would be greater than if wheat were planted after a broadleaf crop such as soybeans. In addition, when environmental conditions are favorable, some level of the disease will occur regardless of rotation sequence. This occurs because scab fungus spores become airborne and can be blown from field to field.

– Avoid planting cultivars highly susceptible to scab and DON. Although no wheat cultivars have even moderate resistance to scab, some have minimal resistance or tolerance to the disease. When selecting cultivars, consider their susceptibility to both scab and vomitoxin. Studies have shown some cultivars that are highly susceptible to scab can accumulate low levels of vomitoxin and some that appear to have some resistance to the disease can accumulate high levels of the toxin.

– Plant several cultivars that differ in flower dates to increase the probability that some cultivars will escape infections. This will reduce the likelihood of overall loss from scab since spores of the scab fungus infect wheat heads mostly during flowering, Wegulo said.

More information about the disease and how to manage it are available in UNL Extension Circular, EC 1896, Fusarium Head Blight of Wheat, available from a local UNL Extension office or the Web.

More information, including tables on scab intensity and a partial list of fungicide seed treatments, also is available in Crop Watch, UNL Extension's crop production newsletter.

9/8/08-SK

Stephen Wegulo - Ph.D.
Plant Pathology
Assistant Professor
402) 472-8735

Sandi Alswager Karstens
IANR News and Photography
(402) 472-3030

Department: Plant Pathology