The announcement by the Illinois Department of Agriculture that the presence of Asian soybean rust has been detected for the first time in Illinois is no cause for major concern, according to experts from University of Illinois Extension.

"The arrival of rust so late in the year will have no impact on the 2006 soybean crop," said plant pathologist Suzanne Bissonnette, who serves as the soybean rust coordinator for University of Illinois (U of I) Extension. "The soybean harvest is already well underway across much of the state. Those areas that have experienced a hard frost will not be affected at all. No management actions should be undertaken by growers or commercial applicators at this time."

The discovery was made in extreme southern Illinois in Pope County near the border with Kentucky. The infected sample came from a mature soybean field at the U of I's Dixon Springs Center. Adjacent counties are currently being sampled to determine the extent of the outbreak.

U of I Plant Clinic Director Nancy Pataky and U.S. Department of Agriculture plant pathologist Glen Hartman diagnosed rust on the samples on October 11. They sent them on the USDA laboratory in Beltsville, Md., for positive confirmation and species verification as indicated by the national protocols for handling the first discovery of the disease in the state.

"The discovery of soybean rust in the southern part of Illinois was not completely unexpected," Bissonnette said. "Officials from the state of Kentucky had recently reported the presence of the disease in eight counties directly adjacent to that section of Illinois.

She notes that information on the extent of the outbreak will greatly facilitate research on soybean rust and aid in the refinement of predictive models for future outbreaks.

"If infection occurs during the vegetative and early reproductive growth stages for soybeans, this disease can cause significant defoliation of the plant and subsequent loss in yield or even death of the plant," Bissonnette said. "Luckily the outbreak this time came late in the season and will have no significant impact on the crop."

Guidelines for management and additional information on soybean rust are available on the national soybean rust website at http://www.sbrusa.net/ and the U of I Crop Sciences Departments website at http://soyrust.cropsci.uiuc.edu/index.cfm.

By Rob Wynstra