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USDA Public Soybean Rust Web Site Purdue University Soybean Rust Hotline - 866-458-RUST (7878) 2007 National Soybean Rust Symposium Proceedings Preparing for Soybean Rust (pdf file) - Purdue publication, order hard copies here
In 2008, soybean rust was found in 16 states representing 392 counties in the United States. This includes 56 counties in Alabama, 66 counties in Arkansas, 82 counties in Georgia, 24 counties in Florida, five counties in Illinois, 32 parishes in Louisiana, four counties in Kentucky, one county in Maryland, 79 counties in Mississippi, one county in Missouri, five counties in North Carolina, one county in Oklahoma, 16 counties in South Carolina, five counties in Tennessee, five counties in Texas, and 10 counties in Virginia. Rust was also reported in 14 municipalities (counties) across four states in Mexico. In 2007, soybean rust pushed farther north and west than in previous seasons, however most areas in the Midwest and plains regions discovered rust late enough in the season that it did not affect production. This is the most widespread and numerous distribution of this disease since it was first discovered in the U.S. in 2004. Asian soybean rust (ASR) is a serious disease caused by the fungus Phakopsora pachyrhizi. Soybean rust is spread by windblown spores and has caused significant crop losses in many soybean-growing regions of the world (pdf file). On November 10, 2004 USDA's Animal and Plant Health Inspection Service (APHIS) announced the first confirmation of Asian soybean rust in the continental United States (Louisiana), followed by finds in 8 additional southern states. In 2005, soybean rust was confirmed on soybeans in 29 counties in Georgia, 23 counties in South Carolina, 21 counties in Alabama, 18 counties in North Carolina,12 counties in Florida, 2 counties in Mississippi, and one county in Louisiana. Phakopsora pachyrhizi is an obligate parasite, meaning that it must have live, green tissue to survive. The host range of the soybean rust fungus is quite broad. In addition to soybeans, the ASR fungus is able to infect over 30 legumes including edible bean crops and kudzu. In November 2005, P. pachyrhizi was confirmed on Florida Beggarweed (Desmodium tortuosum) in Georgia. These additional hosts can serve as overwintering reservoirs for the pathogen and allow for build-up of inoculum, in those environs free from freezing temperatures. The pathogen is well adapted for long-distance dispersal, because spores can be readily carried long distances by the wind to new, rust-free regions. Early symptoms appear as chlorosis and brown flecking on the lower leaves in the canopy. Developing lesions can be confused with symptoms caused by other foliar diseases, such as bacterial pustule, bacterial blight, downy mildew and Septoria brown spot. The key diagnostic features of soybean rust are the cone-shaped pustules that form mostly on the undersides of the leaves and the dusty, light-tannish colored spores that erupt from the pustules. When untreated, soybean rust, causes yield losses due to premature defoliation, fewer seeds per pod and decreased number of filled pods per plant. For state-specific information on diagnosing the presence of soybean rust contact your state's land-grant university diagnostic clinic (pdf file).
Soybean Rust - PowerPoint Presentations
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Site last updated:
13 January, 2009