A spore trap in Champaign County, Illinois has turned up four rust-like spores, but plant pathologists are quick to say that it does not mean that Asian soybean rust has arrived in Illinois.
"No infected plants have been found. The spores are the shape of fungal rust spores but they have not yet been identified as Asian soybean rust," says Suzanne Bissonnette, University of Illinois Extension educator.
Cooperators have been monitoring spore traps and sentinel field plots in Illinois throughout the growing season. This is to assist growers in the state to make economic and environmentally sound soybean rust management decisions and to serve as an early warning to increase infield soybean scouting from a weekly schedule to a three-day schedule in vulnerable areas.
"The word 'rust' refers to a huge family of fungi that infect plants. There are many hundreds of species that infect green plants. For example we have fungal rust species that infect corn and some that infect wheat and some that infect hollyhocks. The list goes on and on," says Bissonnette. "Fungi in the rust family have numerous microscopic features that look similar."
Plant pathologists have been sampling the air for Asian soybean rust spores throughout the state using windsock spore traps. While rust-like spores were found last week, it doesn't mean that those spores are Asian soybean rust.
At this time, Bissonnette says Illinois Extension personnel are recommending that farmers south of Champaign County in Illinois, as well as those within a 200 mile radius, begin diligent scouting for Asian soybean rust on a three-day schedule.
"Check the lower half of 20 plants in five locations in a contiguous field," Bissonnette recommends. Here are steps to take if suspicious samples are found:
* Collect 20 leaflets
* Wrap them in a paper towel
* Double bag them in zip locked bags
* Take them into your local Extension Unit office for pre-evaluation by diagnosticians to determine if further testing at the University of Illinois' Plant Clinic is necessary.
"Our recommendation at this time is not to spray fungicides for Asian soybean rust, no infection has been found," says Bissonnette.
UDSA's official soybean rust reporting Web site is www.sbrusa.net. There you will find reports of 'rust-like' spores "detected" in several states such as Tennessee and Kentucky, and both have yet to find infection. So far this season, Asian soybean rust plant infection has only been detected in Florida, Alabama, Mississippi and Georgia.