Himalayan blackberry has become one of the Pacific Northwest’s most invasive weeds, spreading rapidly from Northern California to British Columbia. A single plant can grow into a six-square-yard thicket in less than two years, crowding out native vegetation and desirable landscape plants.
“Blackberries keep popping up because of their tremendous and effective dispersal potential,” said Brooke Edmunds, horticulturist with the Oregon State University Extension Service. “Blackberry canes can produce hundreds of berries, each full of seeds. Birds and animals feed on the berries and spread the seeds over long distances. Even banana slugs help by eating the berries and dispersing the seeds.”
With persistence and good timing, even large blackberry patches can be brought under control. Physical removal is the most effective long-term strategy, Edmunds said…