I have been trying to eradicate blackberry bushes from part of my yard for a decade now and they seem to be winning the war. I initially carefully dug out any bushes only to see new ones appear from what seemed like microscopic pieces of root that I missed. I weed eat them, and pull out what I can but they persist. I even covered them with black plastic for a couple years. I will not use pesticides, but am wondering if there are any other methods to try. Any help is appreciated!