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Posted 23 October 2007. PMN Crop News.

Soybean Rust Confirmed in Indiana, But Poses No Threat

Purdue University.

West Lafayette, Indiana (October 17, 2007)--A Purdue University scientist on Wednesday (Oct. 17) confirmed that a leaf collected from Owen County on Monday (Oct. 15) had soybean rust, the first confirmed find in Indiana this year.


This is the second year in a row that soybean rust has been confirmed in Indiana, but its late arrival means little for Hoosier farmers.

"It's too late in the season for soybean rust to have any impact on yields," said Greg Shaner, Purdue Extension plant pathologist. "We have been really fortunate that it hasn't arrived until late in the season."

The site where soybean rust was found was a late-planted field in the R6 stage of development, and leaves were starting to lose their green color, Shaner said.

"Once there is a killing frost, any soybean rust in Indiana will be eliminated," he said.

Even though it's too late for the rust to do any damage, this discovery is still important, Shaner said.

"This finding documents that soybean rust arrived and most likely the infection occurred in late September or early October," he said. "It's important because there is a group of people who are modeling the long-distance aerial dispersal of spores by wind and modeling the deposition of the spores as they are scrubbed out of the sky by rain."

The weather models are used to predict where the spores are going. Confirmation of soybean rust helps researchers assess the accuracy of their models and refine them.

Even though rust hasn't been a problem yet in the Hoosier state, Shaner said it still has the potential to become one in the future.

"This is the third year we've had the potential for rust, and it's the third year we've gotten by with no problem," he said. "However, I think it's premature to conclude that rust is not going to be a threat.

"The biggest uncertainty in this whole thing is that for the past three years the southeastern United States has been under a severe drought, and rust does not do well in dry weather. When the weather pattern in the southeast returns to a more normal rainfall and higher humidity it could be a very different picture, and we are not going to know until the drought breaks."

Greg Shaner