WEST LAFAYETTE, Ind. — No soybean rust pustules have been found in the Midwest, including Ohio, Illinois, Indiana, Kentucky and Missouri, according to university experts.
The recent tropical storms in southern parts of the United States have concerned many growers, but soybean rust experts Kiersten Wise, Purdue University Extension; Anne Dorrance, Ohio State University Extension; and Don Hershman, University of Kentucky Extension don’t recommend applying fungicide for soybean rust at this time.
They have however, intensified soybean rust field monitoring efforts by increasing the number of soybean leaves collected in sentinel plots.
Wise said they also are increasing scouting efforts in areas that have even the slightest chance that favorable conditions may have resulted in soybean rust infections.
“Even if we were to find soybean rust this week, it would not be at the level that requires immediate treatment,” Wise said. “In comparison to Brazil, our initial soybean rust spores are extremely low, which gives us extra time to apply fungicides, if they are needed at all.”
In the clear
Experts agree that Kentucky soybeans planted in May and Ohio and Indiana soybeans planted in April, which have reached full pod/beginning seed, are in the clear. They continue to monitor fields for soybean rust because late-planted fields are still at risk.
The most recent soybean rust information and management updates are available at the USDA’s National Soybean Rust Web site www.sbrusa.net.
If soybean rust infection is suspected in any field, samples should be forwarded immediately to the state Extension specialist for diagnosis.
Official confirmation of soybean rust can only be made at the state level and crop insurance claims cannot be processed without the accurate diagnosis.
Soybean rust has never been confirmed in Ohio and must meet Animal Plant Health Inspection Service requirements for a new invasive pathogen. If soybean rust is confirmed in a location, extension educators and certified crop advisors will be notified and updates will be sent out.
From previous years’ research, experts have observed that the spores of soybean rust fungus are killed by sunlight and dessication. This means that most of the spores that reach the traps are more than likely dead, but researchers have no way to measure the viability of spores.
They can only measure if there is a spore. To track soybean rust levels, soybean leaves are collected weekly from sentinel plots located around the state and sent to laboratories, where they are closely examined for soybean rust.
In addition to the sentinel plots, spore traps are used to monitor spores of the soybean rust fungus, Phakopsora pachyrhizae, throughout the United States.
Rain traps are also being monitored, which is a joint collaboration of the United Soybean Board and the USDA’s Agriculture Research Service.
This year, the traps tested positive during June, July and August for spores, which holds true to pattern the previous three years.
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