Comments: The primary threat to the survival of Berberis canadensis has been from the U.S. Department of Agriculture (USDA) comprehensive barberry eradication program. American barberry and most other barberries are alternate hosts for wheat rust (Puccinia graminis), a fungus that has caused major losses in certain grain crops here and in Europe (Hill 2003). Four small-grain crops (wheat, oats, barley, and rye) are all potential hosts to the organism causing black stem rust (BSR). Barberry is an alternate host for the organism causing black stem rust (BSR). Breeding varieties of small grains for resistance to BSR began in the United States around 1900 meeting with rapid success from crosses with wheat varieties from Russia and Turkey. By 1938, farmers were
planting resistant wheat varieties in the areas of the United States where BSR had been most destructive and continued to develop new resistant crop varieties. The difficulty with this approach is that while an individual crop variety may be resistant to several races of BSR, there are more than 200 existing races of BSR. The presence of BSR-susceptible barberry bushes providing the opportunity for new hybrid races of BSR to develop complicates the problem further. The use of resistant crops alone would never provide farmers with adequate protection from BSR. With the increasing demand for U.S. wheat, an alternative method of defense against a catastrophe the magnitude of the BSR epidemic of 1916 was needed.
In 1918, the U.S. Department of Agriculture (USDA) initiated a barberry eradication program in
cooperation with 13 north-central States (Colorado, Illinois, Indiana, Iowa, Michigan, Minnesota,
Montana, Nebraska, North Dakota, Ohio, South Dakota, Wisconsin, and Wyoming). In 1935, four
additional states (Missouri, Pennsylvania, Virginia, and West Virginia) joined the program, followed by Washington State in 1944. This time, the program resulted in the destruction of several hundred million susceptible barberry and mahonia bushes in over 700,000 square miles. Although barberry eradication is a cooperative project with State personnel, USDA has always played a leading role. USDA's funding for the barberry eradication program ended in 1980. Although several States continued some barberry eradication activities, the extensive eradication program also ended in 1980 (APHIS no date, Hill 2003).