The virulent fungus Puccinia striiformis causes stripe rust on many wheat cultivars in China. Technology has been developed that can pinpoint the source of outbreaks and forecast regional epidemics of stripe rust with the accuracy of close to 100%. Studies have elucidated the genetic basis for pathogen virulence as well as disease resistance. A strategy to identify outbreak sources and quickly control spread of pathogen has been implemented across the country, resulted in a significant reduction in grain losses, saving US$1.5 billion.