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.