To be classified as a South Dakota state noxious weed, the weed must be a perennial, spread by underground parts as well as seed. They are difficult to control with normal management operations, capable of decreasing crop and livestock production. A noxious weed decreases land value, and generally impedes the welfare of the people of the state. All of South Dakota's noxious weeds have been imported and most have been introduced as a crop seed contaminant.
Noxious weeds threaten wildlife by displacing native forage and nesting habitat.
They reduce forage and row crop productivity. The aggressive growth of noxious weeds can dramatically reduce establishment and growth of new tree plantings and threaten native endangered plant species. These native plants may be future sources of genetic material or medicines. The increase in soil erosion from noxious weed infestations not only reduces the productivity of the land but increases sedimentation in lakes and streams reducing the quality of fish habitat. Outdoor recreation can be seriously hampered by noxious weeds.