Common barberry (Berberis vulgaris) is the host for the sexual stages of the stem rust fungus that infects wheat, barley, oat, and rye. The U.S. Department of Agriculture in cooperation with state agencies eradicated common barberry from the north-central states. To accomplish this enormous effort took more than 30 years and many millions of dollars. The effort, however, was well-worth the cost. It saved hundreds of millions of bushels of wheat and other cereals that would have been lost to stem rust. Two factors account for these savings. First, eliminating the barberry bushes took away one source of rust spores to infect the cereals each spring in the north-central states. Second, and more importantly, eliminating barberry broke the sexual cycle of the stem rust fungus. This restricted the development of new stem rust races and made it easier for wheat breeders to maintain effective resistance against the existing stem rust races.
	The Cereal Disease Lab guards against accidental reintroduction of rust susceptible barberries into the grain producing regions of the north-central states. Many barberry species are immune to rust and are valuable ornamental species. They are prized for the attractive hedges that they form in home landscapes.
Therefore, it is necessary to identify which barberries can be grown and which must be quarantined from the north-central states. The USDA and state departments of agriculture cooperate to enforce the quarantine. All new barberry varieties proposed for sale must be tested at the Cereal Rust Lab and certified immune to stem rust before they can be registered for interstate shipments.
Rust resistant Berberis, Mahoberberis and Mahonia Rust susceptible Berberis, Mahoberberis and Mahonia Black stem rust biology and threat to wheat growers