Asian Soybean Rust is a serious disease of soybeans caused by the fungus Phakopsora pachyrhizi. Until recently this disease did not occur in soybean in the western hemisphere but it spread to South America in 2001 and was found for the first time in North America in November 2004. It was found in the southern US in 2005, but has not been found in TN since Nov. 2004.
Asian soybean rust was first observed in Japan in 1902. Until recently the pathogen was distributed throughout Asia and Australia. It was reported from Hawaii in 1994. In the late 1990's Asian Soybean Rust was found in Africa and, in 2001, was reported in South
America. As of 2004, Asian Soybean Rust in the Americas is known from Argentina, Bolivia, Brazil, Paraguay, and Uruguay. In November 2004, Asian Soybean Rust was found for the first time in Louisiana and, soon thereafter, in other southeastern U.S. states.
Many earlier reports of Asian Soybean Rust in the Americas are erroneous. The reports of this disease prior to 1992 actually refer to Phakopsora meibomiae, a similar-looking rust that also occurs on soybeans and numerous other legumes.