Control usually combines use of herbicides, prescribed fire, and mowing. Insects for biological control have been released at several hundred sites in the state by the U.S. and Minnesota departments of agriculture. Spotted knapweed probably arrived here in alfalfa or hay seed from Europe and Asia. It reproduces solely by seed. Dry prairies, oak and pine barrens, and sandy ridges are likely natural habitats.
Chemical control can be fairly effective but cost prohibitive.
European and cultivated strains were originally introduced as forage. This widely planted grass has also been used to establish cover on streambanks and wetland projects. Because native plant populations are excluded after this species invades, consider planting alternative native grasses and grasslike plants in conservation projects. Spoilers on the Horizon While battling the plant invaders already here, Minnesotans must also keep an eye out for the many troublesome plants poised to enter from other states and countries. It forms large mats on lake surfaces and hinders boating.