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.