Four 'rust-like' spores found in Illinois

A trap found four "rust-like" spores in Illinois, the nation's biggest soyabean producing state, but the sample is too small to confirm if it is the highly contagious soyabean rust disease, the US Agriculture Department's rust-monitoring Web site said on Tuesday.
The spores were found in Champaign County, in east-central Illinois, on July 29. The county is home to the University of Illinois in Champaign-Urbana, 40 miles north-east of Decatur, a soyabean-processing centre.
"It is not possible to confirm whether these spores are actually soyabean rust spores, but scouting in Champaign County has increased," Linda Kull, an expert with the university's National Soybean Research Laboratory, said in a report posted on the USDA site.
"These are spores that look similar to many kinds of rusts from various hosts, however spores in traps cannot be positively identified with visual, molecular, or culturing techniques," Kull said.
Rust erupts in reddish-brown lesions on soya plants, causing them to drop their leaves and slashing production by as much as 80 percent. Even treated fields can lose up to 20 percent of their yield.
Illinois ranked as the nation's top producer of soyabeans in 2004, with a harvest of 499.95 million bushels out of a nation-wide total of 3.14 billion bushels.
So far this year, the highly contagious soyabean rust has been found in four states - Florida, Georgia, Alabama and Mississippi. Crop scouts and plant disease experts have been checking soyabean fields from Florida to North Dakota to monitor the spread of the disease.
A tiny amount of spores were also picked up by traps in Kentucky and Tennessee this summer, but intensive scouting in both states has yet to confirm soyabean rust.
Kull also said it was premature for any Illinois farmers to spray for soyabean rust.
"According to the USDA soyabean rust forecasting model, spore deposition forecasts show the potential for low levels of soyabean rust spore accumulation in Illinois this week," she said.
"USDA scientists indicated that soyabeans approaching pod and seed fill are at low or no risk of damage by soyabean rust in Illinois. When seeds are nearly mature and begin to dry, the risk of yield loss due to soyabean rust is very low," she added.