CHAMPAIGN, Ill. — Through sampling taken by the University of Illinois (UOI), Asian soybean rust has been confirmed in southern Illinois.

The UOI said rust was discovered in Pope County near the border of Kentucky with the sample from a field at the UOI’s Dixon Springs Center. The discovery has prompted sampling in adjacent counties and detection was made in seven counties.

The rust is believed to have come from wind-borne spores blown into the region from the southern United States about two weeks ago.

The discovery is not a cause for immediate concern, said Suzanne Bissonnette, a plant pathologist and soybean rust coordinator for the UOI.

“The arrival of rust so late in the year will have no impact on the 2006 soybean crop,” she said.

“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.”

Illinois Department of Agriculture (IDOA) Director Chuck Hartke agreed.

“If the fungus had arrived here earlier, when beans were developing and setting pods, it potentially could have caused significant production losses,” he said.

“Fortunately, the crop has matured, harvest is nearing completion and no damage will occur.”

Asian soybean rust has infected 113 counties in 10 states this year. The Illinois and Kentucky cases are the northern-most detections. “Our best defense against soybean rust is a hard frost,” said Jim Larkin, the Soybean Rust Program manager for the IDOA. “The disease simply cannot survive this far north without a green, living host.”

Asian soybean rust (Phakopsora pachyrhizi) causes small, pustular lesions on the foliage and pods of more than 95 plant species, including soybeans. It also infects kudzu, an exotic nuisance weed present in southern Illinois.

While the health of the kudzu plant is not severely impacted by the disease, it serves as a reservoir for the soybean rust pathogen.

The disease was first recorded in Japan in 1903 and identified for the first time in the Western Hemisphere in Hawaii in 1994. It was confirmed in the continental United States in 2004, the same year Illinois adopted a comprehensive plan to identify and control the disease.

The plan, a coordinated effort between the UOI, the Illinois Soybean Assoc. (ISA), Southern Illinois University, National Soybean Research Center, USDA Animal and Plant Health Inspection Service and IDOA, emphasizes early detection and timely fungicide applications.

“The soybean checkoff has taken a lead in Asian soybean rust research and appreciates the working relationship that has developed between these agencies,” Bryan Hieser, Chair of the ISA Supply Committee, said. “Through the efforts of the coordination committee, all the pieces came together and we were able to disseminate the positive find in a timely manner.”

The UOI Plant Clinic diagnosed rust on the leaf samples on Oct. 11 and sent them to a lab in Beltsville, M.D. for confirmatory testing. Results came back positive on Oct. 13. Scouts are surveying other fields to determine the extent of the infestation.

Asian soybean rust is of particular concern to Illinois farmers because of the damage it can cause. Soybeans are a lucrative, $3 billion cash crop in the state, and yield losses in countries where the fungus has gone undetected and untreated have been as high as 80 percent.

“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.”

Bissonnette said details on the extent of the outbreak will facilitate research on soybean rust and aid in the refinement of predictive models for future outbreaks.

“Luckily the outbreak this time came late in the season and will have no significant impact on the crop,” she said.

Management guidelines and additional information on soybean rust are available at www.sbrusa.net and http://soyrust.cropsci.uiuc.edu/index.cfm

This farm news was published in the Oct. 18, 2006 issue of Farm World, serving Indiana, Ohio, Illinois, Kentucky, Michigan and Tennessee.