Land Plants - invasive

Knotweed (unknown species) (Fallopia sp.) on Aug 21, 2009

Submitter does not have a specimen
EDRR Status: Local expert notified

Description of specimen

Japanese Knotweed clump, trailing canes through reed canarygrass to waters edge.


Hello Don,

Thanks for reporting this infestation of knotweed. Knotweed is a significant problem invader in riparian communities within Clackamas County. The Clackamas Soil and Water Conservation District is working with regional partners to map and catalog known infestations of knotweed to help prioritize future control efforts.

Unfortunately, the resources needed to control this invader are limited in relation to the overall need. As such we currently offer technical information to local landowners to help them develop a management strategy that is effective to their particular site conditions and needs. If you would like additional assistance please feel free to contact the Conservation District.

Also please feel free to contact the check these online resources to better manage the knotweed on your property.

When working with knotweed it is important to avoid spreading root and stem fragments into streams and rivers. These fragments will float downstream to grow and develop into new knotweed plants.

If you are planning using chemical control methods avoid drift into streams and adjacent native vegetation. Also be sure to read and follow the label. The label is the law. So be sure you follow all label directions, recommendations, and restrictions.

Again thank you for reporting this invader. Feel free to contact me if you have additional questions.



Samuel Leininger
WeedWise Program Manager
Clackamas Soil & Water Conservation District
221 Molalla Ave. Suite 102
Oregon City, OR 97045
503-655-3144 x118

Samuel Leininger
Sept. 1, 2009, 4:26 p.m.