Description:
Meadow knapweed is a perennial growing from a woody root crown, with 20 to 40 inch tall upright stems. Its basal leaves can be up to six inches long and 1.25 inches wide, tapering at both ends. The stem leaves are lance-shaped, stalkless, and sometimes shallowly lobed, while the uppermost leaves are smaller and not lobed. The rose-purple to occasionally white flowers occur in solitary, oval, or almost globe-shaped flower heads at the ends of branches. The light to dark brown involucral bracts are roundish, with a torn, thin, papery margin, or a comb-like, fringed margin. More apparent on outer bracts, the fringes are about equal in width to the central body of the bract. Meadow knapweed flowers from July to September, producing ivory-white to light brown seeds that may or may not have a barely noticeable plume. However, because it is a hybrid, meadow knapweed traits are highly variable.

• Mechanical: Meadow knapweed may be cultivated out. A fallow program prior to pasture reseeding should eliminate it.
• Biological: The seed head gall fly, Urophora quadrifasciata, has had fair success on meadow knapweed.
• Herbicide: The commonly used selective herbicides are effective - see recommendations in the Pacific Northwest Weed Control Handbook. Refer to the State Noxious Weed Control Board site

For More Information:
Detailed information about Meadow Knapweed is available at the Washington State Noxious Weed Control Board Web Site.