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Noxious weeds

King County, Washington

To offer a suggestion or report an error on the King County Noxious Weeds website, please contact Sasha Shaw, education specialist.

Best Management Practices

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

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Noxious Weed Control Regulatory Guidelines (853 Kb Adobe Acrobat format)
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 (256 Kb Adobe Acrobat format)
Provides an overview of bittersweet nightshade (European bittersweet, Solanum dulcamara) including impacts, background, toxicity, identification, biology and spread, and methods for controlling bittersweet nightshade in a variety of sites, including riparian habitat.

Blackberry Control (228 Kb Adobe Acrobat format)
Provides an overview of invasive blackberries including how to identify them, their biology and impacts on the environment, methods of control for a variety of sites, history in our region and recommendations for further learning. Blackberry species covered include Evergreen blackberry (Rubus laciniatus) and Himalayan blackberry (Rubus discolor, syn. Rubus armeniacus).

Brazilian Elodea Control (283 Kb Adobe Acrobat format)
Provides control and impact information for the non-native invasive aquatic weed Brazilian elodea or Egeria densa, including weed control practices for different types of aquatic areas.

Bull Thistle Control (234 Kb Adobe Acrobat format)
Offers an overview of the common biennial bull thistle (Cirsium vulgare) including how to identify bull thistle, its background and impacts on the environment and agriculture, and how to manage bull thistle in a variety of sites including suggestions for pasture management to minimize the damage of bull thistle to pasture quality.

Common Reed (Phragmites) Control (310 Kb Adobe Acrobat format)
Provides control and impact information for the non-native invasive wetland weed called either common reed or phragmites (Phragmites australis), including control recommendations for different types of sites.

Common Tansy Control (199 Kb Adobe Acrobat format)
Provides an overview of common tansy (Tanacetum vulgare) including impacts and history, identification, biology and spread, local distribution and control methods in a variety of sites including large grassy areas, riparian habitat and roadsides as well as recommendations for further information.

Dalmatian Toadflax Control (269 Kb Adobe Acrobat format)
Provides identification, control, background and impact information for the European invasive plant called Dalmatian toadflax (Linaria dalmatica ssp. dalmatica), including control recommendations for different types of sites.

Diffuse Knapweed Control (204 Kb Adobe Acrobat format)
Offers an overview of the invasive biennial diffuse knapweed (Centaurea diffusa) including how to identify diffuse knapweed, its background and impacts on the environment and agriculture, and how to manage diffuse knapweed in a variety of sites including suggestions for pasture management to minimize the damage of knapweed to pasture quality.

English Ivy Weed Bulletin (743 Kb Adobe Acrobat format)
Provides an overview of English ivy (Hedera helix) and Irish or Atlantic ivy (Hedera hibernica) including which cultivars are considered invasive, the damage that weedy ivys can cause, and how they reproduce and disperse, along with methods of control, disposal advice, and recommendations for additional reference material.

Fragrant Water Lily Control (198 Kb Adobe Acrobat format)
Provides an overview of the floating aquatic noxious weed fragrant water lily (Nymphaea odorata) including impacts and history, identification, reproduction and spread, local distribution, and control methods including prevention, manual, mechanical, biological and chemical methods, permits required for these control methods, and a summary of best management practices including references for further information.

Garden Loosestrife Control  (355 KB Adobe Acrobat format)
Provides an overview of garden loosestrife (Lysimachia vulgaris) including impacts and history, identification, reproduction and spread, local distribution, and control methods including prevention, manual, mechanical, biological and chemical methods, permits required for these control methods, and a summary of best management practices including references for further information.

Garlic Mustard Control
(294 Kb Adobe Acrobat format)
Offers an overview of and specific in-depth information about the noxious weed garlic mustard (Alliaria petiolata) including impacts and history, identification, look alikes, biology and spread, distribution in King County, weed ecology, legal requirements, methods of control, and references for further information.

Gorse Control (374 KB Adobe Acrobat format)
Offers specific, in-depth info about gorse (Ulex europaeus) including description, habitat, how hogweed reproduces and spreads, methods of control, known local distribution, legal requirements, health hazards, weed ecology and ecological hazards, and recommendations for additional learning.

Giant Hogweed Control (285 KB Adobe Acrobat format)
Offers specific, in-depth info about giant hogweed (Heracleum mantegazzianum) including description, habitat, how hogweed reproduces and spreads, methods of control, known local distribution, legal requirements, health hazards, weed ecology and ecological hazards, and recommendations for additional learning.

Hawkweed Control (263 KB Adobe Acrobat format)
Provides specific, in-depth info about several hawkweed species (Hieracium sp.) offering descriptions, habitat, reproduction and dispersal, legal requirements, prevention and control methods, known local distribution, hawkweed impacts and history, and recommended references. Hawkweed species covered include orange hawkweed, yellow hawkweed, and other non-native invasive hawkweed species.

Herb Robert Control (320 KB Adobe Acrobat format)
Provides specific, in-depth info about herb Robert or Robert's geranium (Geranium robertianum) including description, habitat, how this invasive weed reproduces and spreads, methods of control and prevention, legal requirements, history of its spread, known local distribution, and recommendations for additional references.

Knotweed Control (649 Kb Adobe Acrobat format)
Provides an overview of the group of invasive riparian noxious weeds known as invasive knotweed. Species covered are Bohemian knotweed (Polygonum bohemicum), Japanese knotweed (Polygonum cuspidatum), Giant Knotweed (Polygonum sachalinense), and Himalayan Knotweed (Polygonum polystachyum) including impacts and history, identification, reproduction and spread, local distribution, and control methods including prevention, manual, mechanical, biological and chemical methods, permits required for these control methods, and a summary of best management practices including references for further information.

Meadow Knapweed Control (259 Kb Adobe Acrobat format)
Offers an overview of the invasive perennial hybrid weed meadow knapweed (Centaurea jacea x nigra, also known as Centaurea × moncktonii and Centaurea debeauxii subsp. thuillieri) including how to identify meadow knapweed and distinguish it from its parent species black knapweed and brown knapweed and other knapweed species, its background and impacts on the environment and agriculture, and how to manage meadow knapweed in a variety of sites including suggestions for pasture management to minimize the damage of knapweed to pasture quality.

Milfoil Control (407 Kb, Adobe Acrobat format)
Provides identification, history, impacts and control methods for two non-native invasive milfoils, Eurasian watermilfoil (Myriophyllum spicatum) and variable-leaf milfoil (Myriophyllum heterophyllum) including detailed best practices for different types of aquatic sites.

Milk Thistle Control (386 KB Adobe Acrobat format)
Offers specific, in-depth info about milk thistle (Silybum marianum ) including description, habitat, how milk thistle reproduces and spreads, methods of control, known local distribution, legal requirements, health hazards, weed ecology and ecological hazards, and recommendations for additional learning.

Old Man's Beard (Clematis) Control (334 KB Adobe Acrobat format)
Provides an overview of Old Man's Beard (Clematis vitalba) including the damage that this weedy, non-native Clematis can cause, and how it reproduces and disperses, along with methods of control, disposal advice, and recommendations for additional reference material.

Policeman's Helmet Control (163 KB Adobe Acrobat format)
Provides specific, in-depth info about policeman's helmet (Impatiens glandulifera) including description, habitat, how these invasives reproduce and spread, methods of control and prevention, legal requirements, history of its spread, known local distribution, and recommendations for additional references.

Purple Loosestrife Control (304 KB Adobe Acrobat format)
Provides an overview of purple loosestrife (Lythrum salicaria) including which cultivars are considered invasive, the damage that weedy ivys can cause, and how they reproduce and disperse, along with methods of control, disposal advice, and recommendations for additional reference material.

Reed Canarygrass Control (407 KB Adobe Acrobat format)
Provides specific, in-depth info about reed canarygrass (Phalaris arundinacea) including description, habitat, how this plant reproduces and spreads, methods of control and prevention, legal requirements, history of its spread, known local distribution, and recommendations for additional references.

Scotch Broom Control (383 KB Adobe Acrobat format)
Provides an overview and specific, in-depth info about Scotch broom (Scot's broom) (Cytisus scoparius) including descriptions, habitat, how this invasive plant reproduces and spreads, methods of control, known local distribution, legal requirements, weed ecology and ecological hazards, and recommendations for additional learning.

Spanish Broom Control (420 KB Adobe Acrobat format)
Offers specific, in-depth info about Spanish broom (Spartium junceum) including descriptions, habitat, how this invasive plant reproduces and spreads, methods of control, known local distribution, legal requirements, weed ecology and ecological hazards, and recommendations for additional learning.

Spotted Knapweed Control  (187 KB Adobe Acrobat format)
Offers specific, in-depth information about the perennial invasive weed spotted knapweed (Centaurea stoebe ssp. micranthos, also known as Centaurea maculosa or Centaurea biebersteinii) including description, habitat, how it reproduces and spreads, methods of control and prevention, known local distribution, knapweed damage and invasion history, and recommended reference materials for further information.

Sulfur Cinquefoil Control (224 KB Adobe Acrobat format)
Provides in-depth, specific info about sulfur cinquefoil (Potentilla recta) including description, habitat, how they reproduce and spread, control and prevention methods, legal requirements, known local distribution, impacts and history of invasion, and recommendations for additional reading.

Tansy Ragwort Control (186 KB Adobe Acrobat format)
Provides specific, in-depth info about tansy ragwort (Senecio jacobaea) including description, habitat, how they reproduce and spread, methods of control and prevention, legal requirements, damage caused by tansy ragwort and history of its spread, known local distribution, and recommendations for additional references.

Yellow Flag Iris Control (318 Kb Adobe Acrobat format)
Offers an overview of yellow flag iris (Iris pseudacorus) including identification, impacts to riparian and wetland habitat, history, reproduction and spread, habitat, local distribution, and control recommendations including manual, mechanical, and chemical methods for small and large sites in wetlands, streams, roadside and native habitats. Also includes references for further study.

Related Information

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).