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brown knapweed plant

Legal status in King County, Washington

Public and private landowners are required to control infestations of brown knapweed on their property in King County, Washington. Brown knapweed is a Class B Noxious Weed in Washington, first listed before 1988. It is designated for required control by the Washington State Noxious Weed Control Board and is on the list of Regulated Class B Noxious Weeds in King County. For more information, see Noxious Weed Lists and Laws or visit the website of the Washington State Noxious Weed Control Board.

Additional information on brown knapweed

What to do if you find this plant in King County, Washington

Please notify us if you see brown knapweed growing in King County. Our program staff can provide the property owner or appropriate public agency with site-specific advice on how best to remove it. Also, because brown knapweed is not established in King County, we have an opportunity to stop it from spreading if we act quickly. We map all known locations of regulated noxious weeds such as brown knapweed in order to help us and others locate new infestations in time to control them.

Brown knapweed photos

For detailed photos of brown knapweed, see this microscopy UK page with amazingly detailed photos of this species.

Report brown knapweed in King County, Washington

Locate brown knapweed in King County, Washington

Related information

Related agencies


Program offices are located at 201 S. Jackson St., Suite 600, Seattle, WA 98104. To contact staff, see the Noxious Weed Control Program Directory, send an email, or call 206-477-WEED (206-477-9333).