Washington State Noxious Weed Control Board

08/28/2026

Purple loosestrife, Lythrum salicaria, is a Class B Noxious W**d in Washington State. That means it is required for control in many places, but not everywhere! As the negative review says, it is particularly harmful in our wetland habitats!

If our Washington wetlands could write reviews, you can bet they’d give zero stars to purple loosestrife.

This noxious w**d outcompetes native plants for resources, alters wetland structure and function, clogs waterways and irrigation systems, affects agricultural production, and reduces the pasture quality for livestock grazing.

It’s a total buzzkill!

This plant is on Washington’s Noxious W**d Seed and Plant Quarantine list, meaning it’s prohibited to transport, buy, sell, offer for sale, or distribute leafy spurge plants, plant parts, or seeds.

You can help prevent the spread by removing any plants from gardens and not planting them to begin with.

Learn more: https://invasivespecies.wa.gov/priorityspecies/purple-loosestrife/

Photo courtesy of Steve Dewey/Utah State University

08/19/2026

In addition to our beautiful native Oregon ash, ash trees are also popular plantings in gardens and along roadsides throughout Washington. The emerald ash borer will put all of these amazing trees at risk!

https://agr.wa.gov/about-wsda/news-and-media-relations/news-releases?article=47256

📢 : Emerald ash borer has been detected in Washington State near Vancouver. This highly invasive and destructive pest kills up to 99% of ash trees. So far, this pest has not been eradicated in any area where it has been discovered.

Washington has prepared for the arrival of this pest by creating resources for government organizations and individuals. Check out our press release to learn more about this pest and get resources on what you can do now to prepare. https://agr.wa.gov/about-wsda/news-and-media-relations/news-releases?article=47256

08/12/2026

Waterthyme, Hydrilla verticillata, is an aquatic Class A Noxious W**d in Washington State. Brought in as an aquarium plant, it makes a dense mat, which shades out all other aquatic life and impeding recreation.

It is a perfect example of why to never dump your aquarium into the wild!

08/03/2026

Garlic mustard, Alliaria petiolata, is a Class A Noxious W**d in Washington, which heavily impacts forest understories.

It can be identified by its kidney/heart shaped leaves with wavy to toothed edges, quarter inch white flowers, and its garlic scent!

07/28/2026

Clary sage, Salvia sclarea, is a Class A noxious w**d in Washington State, which invades rangeland, reducing habitat for native species and livestock. It looks similar, and is closely related to, meadow clary and Mediterranean sage, which are also Class A w**ds here!

https://www.nwcb.wa.gov/w**ds/clary-sage

07/17/2026

Vochin knapw**d, Centaurea nigrescens, is a Class A Noxious W**d in Washington State. It looks similar to mountain bluet, Centaurea montana (which is on our monitor list to determine invasive impacts.) Vochin knapw**d is known to cause heavy impacts to pasture and natural landscapes.

07/07/2026

Floating primrose-willow, Ludwigia peploides, is an aquatic Class A Noxious W**d in Washington State. They can form dense mats, choking out any desired aquatic life in any aquatic or riparian environment, especially along the banks. It is very important to not dump your aquarium water in the environment.

06/23/2026

Mediterranean Sage, Salvia aethiopis, is a Class A noxious w**d in Washington State. It invades dry rangeland and pasture across Eastern Washington, greatly reducing native habitat and livestock forage. It spreads its seeds across a landscape as a tumblew**d.

06/08/2026

Eggleaf spurge, Euphorbia oblongata, is a Class A Noxious W**d in Washington State. It easily escapes gardens, and can spread through hay and livestock fields, greatly reducing yield and forage. The sap is toxic to humans and livestock.

05/29/2026

Goatsrue, Galega officinalis, is a Class A Noxious W**d in Washington. It grows as a large shrub in the pea family, and it invades wetland areas, quickly pushing out native species. It is also toxic to sheep and goats.