Wheat Stem Rust (Puccinia graminis)

Stem rust of wheat, barley, oat and rye is caused by Puccinia graminis. It was once the most feared disease in wheat growing areas and has caused epidemics dating back to biblical times (Leonard and Szabo, 2005). Until the development of wheat varieties with appropriate resistance this pathogen remained a serious threat wherever wheat was grown and caused major epidemics in the U.S.A. (Roelfs, 1985) and Canada (McCallum et al. 2007). We have enjoyed decreased losses due to this pathogen in recent years because of the work of plant breeders in creating superior varieties containing appropriate and presumed durable resistance genes; however, this lead to complacency and the breeding for stem rust resistance was not a priority in wheat breeding.