Due to the tropical storms that recently moved into the southern U.S. states and the rain that fell recently across much of Minnesota, concern has increased about soybean rust in Minnesota and states to our south. As of July 25, there were no observations of soybean rust in Minnesota or in any states near Minnesota. To our knowledge, spore traps also have not captured soybean rust spores in Minnesota or in nearby states. Although a few possible soybean rust spores have been reported in July from as far north as Kentucky and Tennessee, soybean rust has not been found on soybean or other plants in those states, in spite of extensive scouting and testing. In 2005, soybean rust is still restricted to the deep south and has only been confirmed in a few relatively small locations in southern Alabama, Florida, Georgia, and Mississippi. Soybeans, kudzu, and other susceptible plants have been and continue to be scouted intensively in those and other southern states.

According to soybean rust forecasting models from the USDA and Iowa State University, the risk is low for soybean rust spore deposition in Minnesota and all states to the immediate south of Minnesota including Iowa and Illinois. This is due in part to weather patterns and the presumed low number of spores being produced in the south on the relatively small areas known to be infected. As of July 25, it is not recommended to spray fungicides for soybean rust management in Minnesota and the same is true for states bordering Minnesota to the south, east, and west. Fungicide applications to control soybean rust will probably not be generally recommended until soybean rust is confirmed in a state or possibly in states nearby. It is likely that even if a small number of soybean rust spores were blown recently into Minnesota, it will likely take at least two cycles of infection and spore production (each probably 10 to 14 days) plus frequent wet weather conditions before significant disease severity could occur. Thus, significant soybean rust is unlikely to develop in Minnesota anytime soon, and scouting reports from soybean fields and soybean rust sentinel plots should provide sufficient lead time to effectively spray fungicides if they should be needed this season.

Two key recommendations at this time are to scout fields for soybean rust and other foliar diseases and check the Soybean Rust USA Web site for the latest reports and recommendations from Minnesota and other states regarding soybean rust. When scouting, look first at the underside of leaves on the lower half of the soybean plants. Look at five plants in 20 different locations in a field. Since soybean rust lesions are small and difficult to diagnose because of similarities to several other leaf pathogens, use a 16X to 20X hand lens. Additional information related to soybean rust in Minnesota can be found in the Soybean Rust section of the Minnesota Soybean Production web site at: http://www.soybeans.umn.edu.

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