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King County, Washington noxious weed identification and control

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Non-regulated Class B and C noxious weeds, 2013 list
(Class B and C noxious weeds that are not designated for control in King County, control recommended but not required in King County)

Common name Scientific name State class
blackberry, evergreen Rubus laciniatus  C
blackberry, Himalayan Rubus armeniacus  C
butterfly bush Buddleia davidii  B
common barberry (external link) Berberis vulgaris  C
common catsear (external link) Hypochaeris radicata   C
common fennel (except bulbing variety azoricum) (external link)  Foeniculum vulgare  B
common groundsel (external link)  Senecio vulgaris  C
common St. Johnswort (see note 1 below) Hypericum perforatum  C
common tansy Tanacetum vulgare  C
common teasel Dipsacus fullonum  C
curly-leaf pondweed (external link) Potamogeton crispus  C
Eurasian watermilfoil Myriophyllum spicatum  B
field bindweed Convolvulus arvensis  C
fragrant water lily Nymphaea odorata  C
hairy whitetop (external link) Cardaria pubescens  C
herb Robert Geranium robertianum  B
hoary cress (external link) Cardaria draba  C
ivy, Atlantic Hedera hibernica  C
ivy, English Hedera helix 'Baltica', Hedera helix 'Pittsburgh', Hedera helix 'Star'  C

knotweed, Bohemian (see note 2 below)

 Polygonum bohemicum  B
knotweed, giant (see note 2 below) Polygonum sachalinense  B
knotweed, Himalayan (see note 2 below) Polygonum polystachyum  B
knotweed, Japanese (see note 2 below) Polygonum cuspidatum  B
old man's beard Clematis vitalba  C
oxeye daisy Leucanthemum vulgare  C
perennial sowthistle Sonchus arvensis ssp. arvensis  C
poison-hemlock Conium maculatum  B
reed canarygrass Phalaris arundinacea  C
Scotch broom (see note 3 below)  Cytisus scoparius  B
spurge laurel Daphne laureola  B
thistle, bull Cirsium vulgare  C
thistle, Canada Cirsium arvense  C
tree-of-heaven (external link) Ailanthus altissima  C
wild carrot Daucus carota  C
yellow archangel Lamiastrum galeobdolon  C
yellow flag iris Iris pseudacorus  C
yellow toadflax Linaria vulgaris  C
1. Permit from KC Weed Board required to grow common St. Johnswort as a crop in King County.
2. Control of Bohemian, Japanese, giant and Himalayan knotweed is required on the Green River and its tributaries upstream of the Auburn City Limits and on the Cedar River and its tributaries upstream of the Renton City Limits (tributaries included are those defined as Type S, F or N aquatic areas in KCC 21A.24.355). Control of these invasive knotweed species is required up to the ordinary high water mark (or up to the top of the bank if the ordinary high water mark cannot be identified) and in the adjacent buffer area as specified in KCC 21A.24.358. This requirement to control knotweed is contingent upon the noxious weed program or program partners providing knotweed control services in the selected area for affected private landowners who request assistance. 
3. Control of Scotch broom is required on King County's section of SR-2 and on I-90 between mile marker 34 and the King/Kittitas county line.

King County Noxious Weed List

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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.