A new, highly destructive strain of wheat stem rust is continuing to evolve and has the potential to devastate wheat production worldwide, say plant pathologists with The American Phytopathological Society (APS).

Stem rust of wheat was responsible for massive epidemics on wheat during the early 20th Century in North America. In the mid-1950s, wheat breeders developed wheat that had genetic resistance to the disease, making it all but disappear. Despite this success, a new, virulent strain of wheat stem rust, Ug99, evolved in Uganda and has already spread into Kenya, Ethiopia and Yemen, with the potential to spread into Pakistan, India, and China, and eventually North America.

"This new race could attack wheat varieties in many countries and could virtually overcome most of the wheat resistant varieties around the globe," said David Marshall, research leader with the USDA-ARS, Raleigh, NC.

According to Marshall, if this new strain were to reach regions at risk, it could create epidemics more severe than farmers have encountered in decades and destroy farmers' harvests in wheat-producing areas worldwide.

New information on the research being done nationally and internationally to combat this disease, including with the Global Rust Initiative, will be addressed during the "Stem Rust: A Threat to Global Wheat Production" symposium on August 1 from 8:30 to 11:30 a.m. The symposium will present the latest on new sources for global resistance to stem rust, details on how the disease is mutating, and what’s in store for North America, including information on how the disease affects wheat grown in the U.S. and Canada.

The symposium will be held during the joint meeting of The American Phytopathological Society (APS) and the Society of Nematologists (SON). The meeting will take place July 28 - August 1, 2007, at the Town and Country Resort and Convention Center, in San Diego, Calif.

Source: American Phytopathological Society.