Rusts

“If we fail to contain Ug99, it could bring calamity to tens of millions of farmers and hundreds of millions of consumers. We know what to do and how to do it. All we need are the financial resources, scientific cooperation and political will to contain this threat to world food security.” – Dr. Norman Borlaug

U.S. wheat production and world food security are at risk due to devastating cereal rust diseases including Ug99 wheat stem rust.

Unlike other diseases that may reduce yield or quality, stem rust can kill the entire plant. Ug99 has now spread to South Africa. As the disease continues to spread and intensify in East Africa and the Middle East, the likelihood exponentially increases for the disease to spread to the U.S. by particles carried by the wind or attached to clothing.

Research is being done to assess U.S. wheat varieties’ vulnerability to Ug99, and to identify resistant genes for breeding into new varieties. Improved variety and germplasm development is the only way to get ahead of and minimize the effects of Ug99 when it arrives in the U.S.

In addition to the risk of Ug99, current challenges include leaf rust and stripe rust that cause serious losses in U.S. wheat production nearly every year. Rust pathogens evolve rapidly and have overcome many important genes for resistance.

New, virulent races of stripe rust have appeared since 2002, causing dramatic production losses throughout the U.S. Wheat stripe rust can cause losses of 40 percent, with some wheat fields totally destroyed by the disease. According to USDA, for the three-year period of 2009 to 2011, the U.S. lost 123.0 million bushels to stripe rust; 40.3 million bushels to leaf rust; and 2.2 million bushels to stem rust.

There have been successes in the fight against stripe rust. Researchers at the University of California-Davis, with support from USDA competitive grants, have identified and deployed a gene with resistance to stripe rust so that new varieties being introduced in that state are resistant to new races.