Japanese Knotweed (Fallopia japonica) on Apr 24, 2008
Submitter has sample
Description of specimen
It is actually Japanese knotweed. We moved here 4 years ago, yard was neglected.
Commentary
Thanks for your report. Yes, Japanese knotweed is widespread in the Portland area. It was first introduced as a popular garden ornamental so it is not surprising that it is in your yard. Unfortunately this plant readily escapes into natural areas, and primarily threatens stream-sides since flood events easily spread its roots. I would recommend controlling the patch in your yard since it will probably take over your yard, threaten any structures in your yard, and possible escape to neighboring properties. See this link for control information. http://tncweeds.ucdavis.edu/moredocs/polspp01.pdf. The most important thing in controlling it is to be very carful to properly dispose of the plant material. Thoroughly dry roots and stem on a tarp. Do not attempt to compost. I would suggest hauling the material to the dump. Thanks again for your submission and good luck!
Tania Siemens
April 24, 2008, 10:46 p.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
back yard of 9769 SE 37th Ave, Milwaukie
Expert Reviewer
Tania Siemens WISE Program Coordinator (Watershed and Invasive Species Education) Oregon Sea Grant Extension Oregon State University tania.siemens@oregonstate.edu 541-914-0701
Tania Siemens
April 24, 2008, 10:46 p.m.