Description:
Short-fringed knapweed, also called Vochin knapweed, is a Class A weed in Washington, but has not been classified as a noxious weed in Oregon and Idaho.The flower heads are single at the tips of the branches, more or less flat across the tip of the branches, with the outer flower heads opening first. Flower heads are about 1⁄2 to 3⁄4 inch tall. The outer ring of flowers are sometimes larger than the central flowers in the head. The lower portion of the head, made up of rows of bracts, is oblong, compared to the urn shape of diffuse and spotted knapweed heads. Bracts have small dark triangular tips, with 6 to 8 small fringes on each side which do not taper along the side of the long slender green base of the bract. Flowers are rose-purple and some of this color may tinge the center of the bracts. Seeds are achenes about 1/8 inch long, light brown or ivory with lengthwise lines. If present, the plume consists of a few short stiff hairs opposite the oblique scar where the seed was attached.

Control: Small infestations can be eliminated by repeatedly digging all knapweed plants until seed reserves in the soil are exhausted. How long the seeds remain viable in the soil is not known. Although the woody crown of short-fringed knapweed is too stout for hand pulling, it may be successfully removed using hand tools such as shovels or pulaskis. Dig out as much of the root as possible and plan to return to remove plants that regrow from missed fragments. For larger populations on tillable land, control short-fringed knapweed with repeated cultivation, then reseed to desired pasture species. If short-fringed knapweed responds like other perennial knapweeds, mowing will not control it nor prevent seed production.

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