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.