Description:
Description and Variation: A bushy, branched perennial, Russian knapweed grows one to three feet tall and forms clones or colonies from its vigorous, spreading root system. The erect, hairy stems branch from above the middle or not at all. While young plants may have whitish and woolly stems, older plants will turn dark brown to black. The basal leaves are deeply notched and gray-green in color, while the upper leaves are smaller and linear with broken edges. The stem leaves are intermediate in size with toothed edges. The pink to purple flowers grow in solitary heads at the tips of leafy branches. The bracts under the flower heads are greenish to straw colored, with a broad, papery tip. Russian knapweed flowers from June to September, producing ivory-white seeds with a feather-like plume.

• Mechanical: Productivity is likely to be maximized in a minimum amount of time if Russian knapweed populations can be treated with a suitable herbicide, farmed, and seeded to a competitive forage. Depending on the moisture regime, nitrogen fertilizer applied in conjunction with an herbicide significantly improves the competitiveness of residual grasses.
• Biological: The nematode Subanguina picridis forms galls on Russian knapweed that reduce plant vigor. However, its effectiveness in Washington is not yet known.
• Herbicide: Russian knapweed is difficult to control with herbicides. Depending on the season and the developmental stage of the plant, chlorsulfuron, sodium chlorate, 2,4-D, and picloram are adequate. Read and follow current herbicide labels and recommendations for control. Refer to the State Noxious Weed Control Board site

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