March 16, 2007

On March 13 an Iowa news release announced the first finding of soybean rust in Iowa on some soybean residue in a grain bin. The soybeans were harvested in Mahaska County in southeast Iowa from a low-yielding field. In the 2006 season, Iowa State University had sentinel plots which were two counties east of this location, but rust was not detected in them or any production field during the season. In 2006 we did not see soybean rust active until early October, when many fields had already been harvested.

The confirmation of soybean rust in Iowa crop litter in a grain bin does not pose any added risk that Nebraska will have significant soybean rust developments in 2007. Growers should not be alarmed or assume any added risk for the upcoming season. We have, however, observed more rust each year and further developments will depend on how weather patterns develop. Soybean rust requires green tissue to survive and will not overwinter in Iowa. Each year it will to spread northward from its overwintering locations in the southern U.S.

To keep up with further developments of soybean rust and track its movement, please check the USDA National Soybean Rust Web site at sbrusa.net. There is also a link to this site at the University of Nebraska Web site, Targeting Soybean Rust, at soybeanrust.unl.edu.

Loren J. Giesler
Extension Plant Pathologist