URBANA, Ill. — Soybean rust has been detected for the first time in Illinois during the 2007 growing season from a field in the southern part of the state, according to experts from University of Illinois extension.

“The arrival of rust so late in the year will have no impact on the 2007 soybean crop,” said extension plant pathologist Carl Bradley. “The soybean harvest is already well underway across much of the state. No management actions should be undertaken by growers or commercial applicators at this time, as the soybeans are at a growth stage in which they will not incur yield losses.

“Soybean plants are really most susceptible to yield losses from soybean rust when then are in the R1 (beginning bloom) to R5 (beginning seed) developmental stages. It appears that nearly all of the soybean fields in Illinois – including late-planted, double-crop fields – are behind these susceptible stages; therefore, no losses from soybean rust will be incurred in the state of Illinois in 2007,” Bradley said.

The discovery was made in extreme southern Illinois in Massac County, near the border with Kentucky.

The infected sample was collected by Ron Hines, a trained soybean rust scout with Growmark.

The presence of rust in the sample was confirmed both visually and through DNA testing by plant pathologist Glen Hartman from USDA. “The discovery of soybean rust in the southern part of Illinois again this late in the season was not unexpected,” Bradley said. “Plant pathologists from the state of Kentucky had recently reported the presence of the disease in a county directly adjacent to that section of Illinois.”

Bradley sampled fields in adjacent counties to determine the extent and distribution of the outbreak.

“Soybean leaves from several other counties in southern Illinois were sampled last week after the confirmation in Massac County. To date, no other fields have been confirmed to have soybean rust in Illinois. The incidence and severity of soybean rust in the Massac County field were extremely low,” Bradley said.

“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,” he said.

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

Bradley said while scouting is always important, this incidence should have no effect on next year’s crop.

“The soybean rust pathogen is an obligate parasite, which means that it must have a living host to survive. No susceptible host plants, soybean or kudzu, will survive the winter in Illinois, therefore this year’s find in Illinois will not affect what happens next year,” he said.

Guidelines for management and additional information on soybean rust are available on the national USDA soybean rust website at www.sbrusa.net and the Illinois Soybean Rust Information Center at www.soybean rust.org