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"No infected plants have been found, and the spores are the shape of
fungal rust spores but they have not yet been identified as Asian
soybean rust," said Suzanne Bissonnette, U of I Extension educator
in integrated pest management She says cooperators in Illinois
have been monitoring spore traps and monitoring sentinel field plots
throughout the 2005 growing season. The purpose of the monitoring
has been to assist growers in the state to make economic and
environmentally sound soybean rust management decisions and to serve
as a pre-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," Bissonnette said. "There are many hundreds of species of
rust that infect green plants. For example, we have fungal rust
species that infect corn and some that infect wheat and some that
infect hollyhocks, and the list goes on and on.
"Fungi in the rust family have numerous microscopic features that
look similar, and thus they are organized into the rust family for
purposes of identification by a mycologist or plant pathologist."
Throughout the state, plant pathologists have been sampling the
air for Asian soybean rust spores, using windsock spore traps. And
although rustlike spores were found last week using a microscopic
examination, it doesn't mean that those spores are Asian soybean
rust.
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At this time, Bissonnette says that U of I Extension
recommendations are that farmers south of Champaign County in
Illinois and 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. Suspicious samples consisting of 20 leaflets
wrapped in a paper towel should be double-bagged in zip-locked bags
and brought to your local Extension unit office for pre-evaluation
by diagnosticians to determine if further testing at the U of I
Plant Clinic is necessary.
"Our recommendation at this time is not to spray
fungicides for Asian soybean rust; no infection has been found,"
Bissonnette said.
The official UDSA soybean rust reporting website at
www.sbrusa.net has reported the
detection of "rustlike" spores in a number of states to the south of
Illinois, such as Tennessee and Kentucky, and both have yet to find
infection. Asian soybean rust plant infection has been detected this
season only in Florida, Alabama, Mississippi and Georgia.
"So don't overreact to the spore findings in Illinois,"
Bissonnette said. "But it would still be wise to redouble your
soybean scouting efforts. You will save yourself time, money and
will be a continuing good steward to the land by getting the right
information before reacting."
[University of Illinois
Extension news release]
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