Cowlitz County Noxious Weed Control Board

03/16/2026

Sunflower broomrape, Orobanche cumana, is now a Class A Noxious W**d in Washington. We only know of one infestation site, but it could be elsewhere! Help us keep an eye out, in the summer look out for a fuzzy, ghostly asparagus looking plant near sunflowers, tomatoes, to***co, and sage!

For more information, see our new information page on it!
https://www.nwcb.wa.gov/w**ds/sunflower-broomrape

08/15/2025

Tip of the Week: Noxious W**d Topic – Knotw**d

Don’t let the sound of its name fool you, Knotw**d is indeed a noxious w**d. You’ll notice jointed stalks like bamboo, alternating heart-shaped leaves, and in late summer, white flower clusters reaching upward. The three species of knotw**d differ in size: Japanese Knotw**d grows roughly 6 feet tall, Giant Knotw**d grows approximately 12 feet tall, and Bohemian Knotw**d (a hybrid of the first two) can be anywhere in between, at which point other features are considered.

Despite their ornamental beauty, knotw**d species destroy aquatic ecosystems, increase erosion, degrade wildlife habitat, and displace native species. Once established, knotw**ds are very difficult to control. Fragments of the plant can re-root downstream or if cut and left in the soil.

While these species prefer streamside habitat, they can also establish in drier sites, including landscape areas. Knotw**d’s aggressive growth habit can damage foundations and roads. If you find knotw**d on your property, please consult the WSU Extension plant and insect clinic or your local noxious w**d control program for advice.

**ds

https://www.nwcb.wa.gov/w**ds/japanese-knotw**d

08/12/2025

🚫 Effective this Saturday, the state plant quarantine list will have new plants 🌿 which will no longer be allowed to be sold in the state. Check out our latest blog for the full list! https://agr.wa.gov/about-wsda/blog-posts?article=44368

07/31/2024

PSA: Tansy populations are high this year. Please contribute to the control of this species in our community. Thank you to those that have been after this for years! Tips for success here:

DO remove the plant. Cut low to the ground and bag all flower heads. Hand pulling is effective if the entire root is removed. Mowing will reduce seed production, but it may cause this typical two-year plant to convert to a perennial.
DO remove only the flower heads from plants that have cinnabar moths present, leave the rest for their feed. They are the black and yellow striped caterpillars often found on Tansy plants
DO place tightly closed bags of tansy in your regular household garbage can
DO consider wearing gloves, some individuals have a skin reaction to this plant
DO help others if you can, ask others for help if you can’t – this really is a community issue

DON’T spray flowering plants with herbicides, IT'S TOO LATE!! Please do consider spraying rosettes in the fall, or rosettes and bolting plants in the spring before bud development
DON’T leave removed flowerheads on the ground or in compost to decompose, seeds will still develop! Each plant offers up to 150,000 headaches that can appear over the next 16 years.
DON’T leave dried plant parts on the ground near livestock. Once dried, it remains toxic but loses the warning smell and bitter taste making livestock far more likely to eat it.

Statewide information can be found here:
https://www.nwcb.wa.gov/w**ds/tansy-ragwort

06/26/2023

01/06/2023

Join our team as a Noxious W**d Field Inspector! This position is full-time with benefits. Apply by January 15th on the County website.

General Position Summary:The Field Inspector is responsible for identifying noxious w**ds, collecting data, communicating with landowners, prescribing control methods, handling and applying herbicides, documenting treatments, attending educational events, participating in workshops and training cour...

08/05/2022

Tansy is toxic to livestock.