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Gardening Answers Knowledgebase

Search Results for: Weed control--Pacific Northwest | Search the catalog for: Weed control--Pacific Northwest

Plant Answer Line Question

Keywords: Goats, Blackberries, Weed control--Pacific Northwest

I am wondering about an environmentally sensitive way to get rid of blackberries. I understand that mowing them consistently for 4 years works, but unfortunately this is not an option because of the terrain. If an herbicide is our only option, can you recommend one that has minimal impact? The area is quite large - a mile long and 20 feet wide.


Invasive.org has produced a document entitled Controlling Himalayan Blackberry in the Pacific Northwest. It includes manual removal, shading, grazing, biological controls, and last-resort herbicide information. (We cannot recommend any specific herbicides, as we are not licensed pesticide handlers.)

The Northwest Coalition for Alternatives to Pesticides has information on nonchemical blackberry control.

For additional information, phone the Master Gardener's DialExtension (King County) at 206-296-3425 (or 800-325-6165, ext.6-3425) and listen to tape #1274 about removing blackberries. However, the solutions given in this tape may apply to smaller areas, rather than the larger stand you mentioned.

An interesting idea that some people are trying locally is the use of goats. This article in the Seattle Post-Intelligencer mentions Healing Hooves of Spokane. There is at least one company on Vashon Island which offers this service as well. Another P-I article mentions Rent-a-Ruminant.
This document from Sound Native Plants contains contact information for several such services.

Date 2017-04-15
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Plant Answer Line Question

Keywords: Rubus discolor, Roadside plants, Weed control--Pacific Northwest

I live next to a Washington Department of Transportation I-5 easement land where the department has let blackberries run rampant. As a result, I have thousands of blackberry seedlings in two areas of my property at this time of year. Is there any effective way to kill them at this stage?


In King County, Himalayan blackberry is a Class C noxious weed, meaning that control is not required by law, but is recommended in natural areas and restoration sites.

University of California, Davis Integrated Pest Management describes various methods of controlling blackberry.

In Ann Lovejoy's Seattle P-I article dated, Thursday, June 7, 2001, she describes vinegar-based herbicide as a means of controlling weedy blackberries and horsetail.

You may also want to contact WSDOT's roadside vegetation maintenance department to report the problem with unwanted blackberries migrating onto your property.

Another option, increasingly being used for large areas with invasive weeds, is to rent goats, who will eat the weeds down to the ground. The Seattle Post-Intelligencer published an article on this subject in 2007. "Rent-a-Ruminant" on Vashon Island is one example of a goat rental service.

Date 2018-04-11
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Plant Answer Line Question

Keywords: caterpillars, Senecio jacobaea, Biological control, Noxious weeds--Washington, Weed control--Pacific Northwest

I was just walking through a wild area in Seattle with lots of weeds, and came across some strange caterpillars. They are mostly hairless (to the naked eye, anyway), and are striped black over orange with black legs. Can you tell me what they are?


I believe you may have seen the Cinnabar moth caterpillar, Tyria jacobaeae, which was introduced to the United States to control a noxious weed, tansy ragwort (Senecio jacobaea). Here are pictures to compare, and more information:
Flickr image

Both Washington State's noxious weed control board and King County Noxious Weeds have information on weed control with Cinnabar caterpillars. (See page 5 of the document). Tansy ragwort is a Class B noxious weed, and control is required in King County.

Date 2017-04-14
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Plant Answer Line Question

Keywords: Lamium galeobdolon, Weed control--Pacific Northwest, Pesticides

Is it safe to use a product like RoundUp to get rid of invasive plants such as Yellow archangel in my yard? What do you suggest?


Do you have a large area covered with Lamium galeobdolon (Yellow archangel, formerly known as Lamiastrum)? I successfully eradicated this plant from my garden by hand-pulling persistently over a few months. This method is certainly safer than using herbicide, but if you have a vast area to tend, it may be harder to achieve. King County Noxious Weed Control has factsheets on this plant which mention various methods of control, including chemical. Because we are librarians and not licensed pesticide handlers, by law we can't actually recommend use of a particular pesticide. Note that the information linked here does say that RoundUp (glyphosate) isn't as effective as some other products. You may also want to take into account the costs of using pesticides in a home garden (where they may affect other non-target plants as well as wildlife, pets, and human inhabitants) against the perceived benefits (perhaps faster and easier than manual control).

The following information about eradicating Lamium galeobdolon is from the Washington State Noxious Weed Control Board:
"Response to Mechanical Methods: Viny plants are easily pulled out by hand during the fall through early spring; however, great care must be taken to remove all parts of plant, as rooted fragments will regenerate (Graham, 2003). It should be noted that L. galeobdolon is highly susceptible to trampling (Packham, 1983)."

If your question is about the safety of glyphosate (RoundUp active ingredient), you may want to read the Northwest Center for Alternatives to Pesticides page about it.

Date 2017-04-14
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May 31 2018 13:14:08