Japanese knot weed

Asked June 26, 2014, 10:31 PM EDT

While reading about invasive plants, I finally identified a mysterious plant in my yard: Japanese Knotweed. In Hood River, the poster said to report any sightings to the county. I live in Salem. Do I try to eradicate this plant myself? It is also growing on the other side of the fence in the neighbor's yard. (I showed photos last year of it to a good plant nursery and they didn't recognize it.)

Marion County Oregon

1 Response


If you require assistance with identification of plants in the future, we can help you in the OSU Extension Marion County office. Japanese knotweed is considered a "B" list noxious weed by the Oregon Department of Agriculture, the agency in charge of regulating and managing weed problems statewide. The link below takes you to the page on the ODA website for knotweed control.

In Marion County, if you would like assistance with managing this problem, the contact person are in the following link. There is a lot of weed management information available through the ODA website:

The management information I have is from the PNW Weed Management Handbook, which lists Japanese Knotweed as a problem weed. The link below takes you to that page. Note that for homeowners, I believe of the listed products, the ones available are glyphosate and Crossbow.

If you would like further assistance please feel free to email me directly.