Breeding successes with spring wheat germplasm

University of California and U.S. Department of Agriculture scientists have been conducting a wheat breeding program at Davis since the 1920s. In the early years, germplasm resources came from the old California cultivars, with their characteristic white grain. The situation changed dramatically in 1961 when a previously unimportant disease, stripe rust (Puccinia striiformis), devastated much of the crop in the Sacramento Valley. During that year, varieties from Mexico proved resistant and replaced the original cultivars in California commercial production.