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To offer a suggestion or report an error on the King County Noxious Weeds Web site, please contact Sasha Shaw, education specialist.
King County, Washington Noxious Weed Identification and Control

Himalayan knotweed
Polygonum polystachyum

New Invasive knotweed control videos video

himalayan knotweed plant with flowersA Class B weed in Washington State, this aggressive competitor in the Buckwheat Family was introduced from Asia as an ornamental. Control of this plant in King County is not required but strongly recommended.

For more information about Himalayan knotweed, please see the written findings of the WA State Noxious Weed Control Board.

Read an informational handout on Himalayan knotweed (156 KB Acrobat file, 22 seconds on 56K modem) or for comprehensive biology and control information, download the Invasive Knotweed Best Management Practices (281 KB Acrobat file).

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Program offices are located at 201 S. Jackson St., Suite 600, Seattle, WA 98104. To contact a staff member at the King County Noxious Weed Control Program, please call 206-296-0290 or by reach them by email.