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College of Food, Agricultural, and Environmental Sciences


Scouting for Soybean Rust Not Over Yet

September 9, 2005

WOOSTER, Ohio — Scouting for soybean rust in Ohio is not quite over yet.

Anne Dorrance, an Ohio State University Extension plant pathologist with the Ohio Agricultural Research and Development Center, said there is a slight possibility that soybean rust spores, potentially carried by rains and wind last week from the remnants of Hurricane Katrina, may find their way to Ohio soybean fields. The impact from infection, however, would be negligible.

"There is always the chance that rust spores carried north from the hurricane will land on soybean fields somewhere in Ohio," said Dorrance, the state's leading soybean rust researcher. "But it doesn't matter at this point if it happens or not. Because of the maturity of the soybean crop, soybean rust would arrive too late and be too dilute to have any impact on yields."

Soybean rust infections continue to spread throughout the south, according to the U.S. Department of Agriculture. To date, 54 counties from five states (Mississippi, Alabama, Georgia, Florida and South Carolina) have confirmed the disease in soybean fields. For the latest soybean rust updates, log on to the USDA's soybean rust information site at

Dorrance said that Extension educators will begin scouting late planted fields for the presence of the disease within the next two weeks. Some fields, planted after the Fourth of July, will also be targeted.

"Two weeks is how long it takes for us to detect the infections that occurred once spores have been potentially deposited on a plant," said Dorrance. "If rust is to show up in Ohio, we'll probably begin seeing something by the end of the month."

Growers are being encouraged to bring any suspicious-looking plant material to Farm Science Review for analysis. The event, being held Sept. 20-22 at Molly Caren Agricultural Center in London, Ohio, will provide information on the disease and demonstrate how to detect and diagnose it.

"If rust does show up in Ohio, it'll be a good educational opportunity and training tool for growers, so they can see what the disease looks like first-hand rather than relying on just a model," said Dorrance. "Plus, confirmation of the disease in the state is important to researchers because it'll give us a basis to determine how long it would take for the disease to reach Ohio from storms that would come up from the south. We'd need that timetable for management for a future season."

According to the Ohio Agricultural Statistics Service, Ohio's soybean crop has already set pods and is in the stages of maturing. Plant yellowing and the dropping of leaves are signs of that progress.

Candace Pollock
Anne Dorrance