In the 1950s, a fatal strain of wheat stem rust invaded North America, ruining 40 percent of the spring wheat crop. Scientists then developed high-yield rust-resistant varieties that helped launch the Green Revolution. But 50 years later, virulent new strains of the pathogen emerged unexpectedly in Uganda, putting most of the world's wheat at risk.

Two other rusts pose threats to wheat -- leaf and stripe, or yellow rust. Stem rust, of which Ug99 is a variant, is the most feared because it can quickly lead to the loss of an entire harvest.

Since 2008, when the DRRW project was first funded with $26.8 million from the foundation, researchers have distributed new resistant wheat varieties for testing and evaluation in 40 countries; strengthened nurseries in Kenya and Ethiopia for screening wheat for vulnerability to rusts, and distributed nearly five tons of Ug99-resistant seed for planting in the at-risk nations of Ethiopia, Kenya, Egypt, Pakistan, Afghanistan, Bangladesh and Nepal.

Initially called to arms by Nobel Prize winner Norman Borlaug, the DRRW works closely with the Borlaug Global Rust Initiative on a global strategy to avert agricultural disaster for wheat.

Linda McCandless is associate director of communications, International Programs, College of Agriculture and Life Sciences.