[files.cfc.umt.edu] Non-native, Spread in US: It was first introduced to the United States in 1873 when flaxseed that had been brought to and planted in South Dakota was found to be contaminated by Russian thistle seeds. From there the weed quickly spread and established itself. In 1894 Lyster Dewey emphatically noted the quick spread of the weed, particularly in comparison to Canada thistle, a weed that had not spread as quickly though it had been present in North America for one hundred years. By 1892, Russian thistle made its first appearance in Colorado; merely two years later, a third of the state reported the presence of the weed. Historic management varied depending on the stage in which the thistle was to be treated. Several authors suggested pulling the weed when young prior to seeding and others recommended burning the plant?a method that is now discouraged due to Russian thistle?s ability to easily establish itself and out compete other plants in disturbed areas. (link added by Mary Ann Machi)