WEST LAFAYETTE, Ind. – Asian soybean rust has been found in Indiana for the first time, but poses no threat to Indiana soybean producers this year. Because more than 90 percent of Indiana soybeans already have been harvested or have at least reached maturity, there isn’t much green, leafy plant tissue remaining for rust to infect, said Greg Shaner, Purdue University Extension plant pathologist.
“The soybean rust fungus only survives on living host plants, so here in the temperate region where we have winter and killing frost, it will be eradicated,” Shaner said.
“So the soybean rust fungus will only survive in North America in the far south – Florida, perhaps along the Gulf Coast and maybe northeastern Mexico. It just depends on how far south the frost extends.”
Still safe. In order for soybean rust to return to the Midwest, the spores would need to build up again in regions where no killing frost existed and winds would have to carry the spores northward. Thus, spores are no more likely to return next year than they were before the find.
The latest instances of soybean rust were confirmed Oct. 18 by the USDA from fields of double-crop soybeans in Knox and Posey counties. This find most likely originated from the same introduction of spores that infected several counties in western Kentucky and southeastern, Illinois.
What this means for Indiana soybean producers is that if soybean rust returns to the Midwest in future growing seasons, the process for identification will move much more quickly.
Once a state first finds soybean rust, plant samples are sent to a lab in Beltsville, Md., for confirmation. Once this one-time process is completed, a state can diagnose future finds on its own and can immediately get word to growers.
Learning. From this latest confirmation, researchers were able to learn more about how soybean rust spreads.
“Perhaps the most important thing we have learned from the appearance of soybean rust in Kentucky, Illinois and Indiana is that southerly winds can carry spores long distances,” Shaner said.
“Winds carried these spores more than 500 miles before they landed and these were still viable after the long journey.”
STAY INFORMED. SIGN UP!
Up-to-date agriculture news in your inbox!