Asian Soybean Rust has been officially confirmed in Illinois, following a positive test on soybean leaves from Pope County, located deep in southern Illinois.

The University of Illinois Plant Clinic diagnosed rust on leaf samples collected in a University of Illinois test plot adjacent to a sentinel plot on Oct. 11 and sent them to a USDA lab in Beltsville, Md., for confirmation testing. Scouts will now survey other fields to determine the severity and extent of the infestation.

The detection didn't come as a tremendous surprise to officials, as rust was detected one week prior in seven Kentucky counties, located just across the border from Pope County. The wind-borne spores that cause the disease are believed to have blown into the region from the southern United States about two weeks ago.

"This discovery, this late in the growing season, will have no impact on the 2006 soybean crop," says Illinois Director of Agriculture Chuck Hartke. "If the fungus had arrived here earlier, when beans were developing and setting pods, it potentially could have caused significant production losses. Fortunately, the crop has matured, harvest is nearing completion and no damage will occur."

Asian soybean rust now has infected 113 counties in ten states this year. The Illinois and Kentucky cases are the northern-most detections.

"Our best defense against soybean rust is a hard frost," says Jim Larkin, IDOA Soybean Rust Program manager. "The disease simply cannot survive this far north without a green, living host."

Good news?

The good news, in technical terms, is that Illinois researchers can now begin lab testing of soybean rust. That sort of testing was not allowed prior to rust's detection in Illinois.

Plant pathologist Suzanne Bissonnette, who serves as the soybean rust coordinator for U of I Extension, notes that information on the extent of the outbreak will help rust research on soybean rust. It should also help them refine 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 says. "Luckily the outbreak this time came late in the season and will have no significant impact on the crop."