King County's Best Management Practices (BMP's) help landowners control weeds using a variety of options that consider characteristics of the site and keep negative side effects to a minimum. The Noxious Weed Control Program follows county guidelines of Integrated Pest Management (IPM). The goal is to maximize effective control and to minimize environmental, economic and social damage.

The BMP documents listed below for individual noxious weed species (or group of species) cover impacts, history, identification, reproduction and spread, local distribution, and control methods including prevention, manual, mechanical, biological and chemical methods, a summary of recommended best management practices for different sites, disposal guidelines and references for further information. You will need Acrobat Viewer to read these documents.

Noxious Weed Control Regulatory Guidelines
Provides guidelines on federal, state and county regulations that relate to noxious and invasive weed control in King County including the State Noxious Weed Law (RCW 17.10), regulations relating to clearing and grading and critical areas and regulations that protect clean water as they relate to control of noxious weeds.

Bittersweet Nightshade Control
Bittersweet nightshade (Solanum dulcamara)

Blackberry Control
Evergreen blackberry (Rubus laciniatus) and Himalayan blackberry (Rubus discolor, syn. Rubus armeniacus).

Brazilian Elodea Control
Brazilian elodea (Egeria densa)

Bull Thistle Control
Bull thistle (Cirsium vulgare)

Common Reed (Phragmites) Control
Common reed (Phragmites australis)

Common Tansy Control
Common tansy (Tanacetum vulgare)

Dalmatian Toadflax Control
Dalmatian toadflax (Linaria dalmatica ssp. dalmatica)

Diffuse Knapweed Control
Diffuse knapweed (Centaurea diffusa)

English Holly Control
English holly (Ilex aquifolium)

English Ivy Control
English ivy (Hedera helix) and Irish or Atlantic ivy (Hedera hibernica)

Fragrant Water Lily Control
Fragrant water lily (Nymphaea odorata)

Garden Loosestrife Control
Garden loosestrife (Lysimachia vulgaris)

Garlic Mustard Control
Garlic mustard (Alliaria petiolata)

Giant Hogweed Control
Giant hogweed (Heracleum mantegazzianum)

Gorse Control
Gorse (Ulex europaeus)

Hawkweed Control
Hawkweed species (Hieracium sp.) including orange hawkweed, yellow hawkweed, and other non-native invasive hawkweed species

Herb Robert Control
Herb Robert (Geranium robertianum)

Knotweed Control
Bohemian knotweed (Polygonum bohemicum), Japanese knotweed (Polygonum cuspidatum), Giant Knotweed (Polygonum sachalinense), and Himalayan Knotweed (Polygonum polystachyum)

Meadow Knapweed Control
Meadow knapweed (Centaurea × moncktonii)

Milfoil Control
Eurasian watermilfoil (Myriophyllum spicatum) and variable-leaf milfoil (Myriophyllum heterophyllum)

Milk Thistle Control
Milk thistle (Silybum marianum)

Old Man's Beard (Clematis) Control
Old man's beard (Clematis vitalba)

Parrotfeather Control
Parrotfeather (Myriophyllum aquaticum)

Policeman's Helmet Control
Policeman's helmet (Impatiens glandulifera)

Purple Loosestrife Control
Purple loosestrife (Lythrum salicaria)

Reed Canarygrass Control
Reed canarygrass (Phalaris arundinacea)

Scotch Broom Control
Scotch broom (Scot's broom) (Cytisus scoparius)

Spanish Broom Control
Spanish broom (Spartium junceum)

Spotted Knapweed Control
Spotted knapweed (Centaurea stoebe)

Sulfur Cinquefoil Control
Sulfur cinquefoil (Potentilla recta)

Tansy Ragwort Control
Tansy ragwort (Senecio jacobaea)

Wild Chervil Control
Wild chervil (Anthriscus sylvestris)

Yellow Archangel Control
Yellow archangel (Lamiastrum galeobdolon)

Yellow Flag Iris Control
Yellow flag iris (Iris pseudacorus)

 

Related information

• Agriculture in King County
• NW natural yard and garden
• Animals, plants and habitat

Related agencies

• Water and Land Resources Division
• Permitting and Environmental Review

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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).