Manage scab with variety selection
Fusarium head blight (aka scab) is one of the greatest threats to Illinois wheat producers. In addition to causing yield reductions and poor test weights, the fungus that causes the disease, Fusarium graminearum, can produce chemicals known as mycotoxins, such as deoxynivalenol (DON), that contaminate grain. Certain mycotoxins can be a serious problem for producers and millers because of limitations on the amounts allowable in food and livestock feed. In some severe cases, harvested grain contaminated with high levels of DON may be rejected for sale.
As described in issue 3 of the Bulletin (April 22), the most effective way to manage scab and DON is to integrate management practices. Studies at the University of Illinois have determined the following combination of practices as best for managing scab and DON: sowing wheat into fields previously cropped to soybean (rather than corn), planting the most scab-resistant varieties available, and spraying a fungicide when the crop begins to flower (if needed, based on the presence of weather favorable for scab).
Of these practices, growing the most scab-resistant varieties available may be the most important. For the past several years, the research program of Dr. Fred Kolb (small grains breeder at the University of Illinois) has screened wheat varieties for their level of scab resistance in the field. The varieties are evaluated in a mist-irrigated field nursery with uniformly high levels of scab. Results from the 2011 evaluations are available at the University of Illinois Variety Testing website under the "small grains" section. Using these results to choose the most scab-resistant varieties available for planting this fall will help provide the best foundation for scab management for the 2011-12 wheat growing season.
Support for scab research at the University of Illinois has come from the U.S. Wheat and Barley Scab Initiative.