Land Plants - invasive

Japanese Knotweed (Fallopia japonica) on Aug 26, 2024

Submitter does not have a specimen
EDRR Status: Population assessed

Description of specimen

See above - classic clumps, on private land.

Commentary

Thanks, Mike, for the report! Our office (West Multnomah Soil & Water Conservation District) will be treating the patches below Cornelius Pass road, as part of our ongoing knotweed control program along McCarthy Creek. Expect treatment to occur sometime in the next month. I will notify Scappoose Bay Watershed Council regarding the patch you found along Scappoose Creek. Thanks again for taking the time to make these reports!

Michelle Delepine
Aug. 28, 2024, 2:56 a.m.

Remedy

Oregon State University's Solve Pest Problems page has some great information about how to get rid of knotweeds Solve Pest Problems

This is a tricky weed to manage. Consider reaching out to your local Soil & Water Conservation District for technical advice.

Location

Japenese Knotweed appears to be getting a start in two new locations - it is limited in these areas and might still be prevented from taking over:
1. in the creek below Cornelius Pass road, about 1/2 mile up from highway 30. Appears to be 3 or 4 clumps down by the stream.
2. Along Scappoose Creek on north side of Scappoose Vernonia Highway, about 4 miles up from Highway 30.

I'm available to provide a better description if needed.

Expert Reviewer

Michelle Delepine
West Multnomah Soil & Water Conservation District
4-County Cooperative Weed Management Area
Willamette Aquatic Invasives Network
Oregon Invasive Species Council

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