Land Plants - invasive

Japanese Knotweed (Fallopia japonica) on May 8, 2008

Submitter has sample

Description of specimen

Large stand of plants that appear to be similar to bamboo. Stalk of plant is reddish green with knee joints at various lenghts. Leaves are green and triangular shaped. Tallest plants are about 8 feet high. Plants have not bloomed yet.

Commentary

Dear Lisa,

Thanks for reporting knotweed. Yes, this is a very aggressive invader that is taking a foot hold in Oregon. Unfortunately it is quite abundant in the Portland area. I would recommend controlling your patch before it spreads further. You can consult the following link for control guidlines. http://tncweeds.ucdavis.edu/moredocs/polspp01.pdf

You may also want to find out who owns the adjacent property to inform them of the problem and perhaps offer to help them control it.

Good luck!

Tania
The Nature Conservancy EDRR Program Coordinator

Tania Siemens
May 9, 2008, 6:03 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

The Japanese Knotweed is growing up into our yard from a large overgrown field behind our house. The shoot in our yard has grown 3 feet tall in 2 weeks. Over the fence, there is a stand of 10-20 shoots of knotweed, all about 8 feet tall with stalks as wide as a quarter. I am not sure who owns the land because it resides between many different homes. We can cut out the plant in our yard but it is only going to grow rampant in the field behind our house.

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

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