We live on 5 acres just outside Eugene city limits on the SW. We had several mounds of blackberries ground to dust with a tractor pulling an implement and then used chemicals 3 times on the new sprouts when we first moved in, but now 4 years later, the mounds are bigger than ever. What is the preferred method of eradicating them? Thanks!
Lane County Oregon invasive species
Generally on old growth blackberries, it is a question of perseverance. You started well with the tractor, but all new growth must be mown before it reaches 12". One of the best controls is pasturing goats on them. They will solve the problem usually in a couple of years or less.