Land Plants - invasive

Japanese Knotweed (Fallopia japonica) on May 31, 2015

Submitter has sample
EDRR Status: Population assessed

Description of specimen

Hollow stem. Leaves are not heart-shaped so I do not think it to be Giant knotweed.

Commentary

Jerry,

Thank you for the report of Japanese knotweed. This is a species that we are definitely concerned about. I have been out on site here, and the infestation is quite extensive along much of the Molalla River. We are currently working in a targeted sub-basin of the Molalla, and your report will help us target future control activities. Thanks for your time and effort reporting these sightings.

Sam

______________________________________

Samuel Leininger
WeedWise Program Manager
Clackamas Soil & Water Conservation District
221 Molalla Ave. Suite 102
Oregon City, OR 97045
503-210-6006
sleininger@conservationdistrict.org
______________________________________

Samuel Leininger
June 5, 2015, 1:20 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

One large shrub of Japanese knotweed near the boat ramp - see first two photos. The last two photos (#3 and #4) are of a large population of knotweed just across the river on the west bank, which is to the west-southwest of this shrub marked. You can also walk along the path on the east side of the river to the south and find several more knotweeds.

Expert Reviewer

Samuel Leininger
Clackamas Soil and Water Conservation District
4-County Cooperative Weed Management Area
Columbia Gorge Cooperative Weed Management Area

© 2025 Portland State University | Contact us for questions regarding site content