The task of getting rid of wild blackberries is one that requires persistence on the part of the landowner. While there are several methods you can try to eradicate the wild blackberries, the best possible method is to use a chemical solution intended for brush control. Until the brush control chemical can be sprayed in the fall, digging and mowing the wild blackberries will help keep them under control.
Use a lawn mower or a string trimmer to cut down the wild blackberry canes as they begin to emerge in the spring. Cut down all traces of the blackberry stems.
Use a shovel to dig up as many of the crowns and roots of the blackberry plants as possible. Dispose of these roots in the garbage or another place where they cannot take root again.
Continue to mow and dig up roots during the summer months. Blackberries can grow from small bits of root left in the ground, so digging up the roots will be an ongoing process during the summer.
Spray the area with brush control herbicide in the late fall before the first frost. Depending on how heavy the wild blackberry growth is, you may need to apply the herbicide several times during the fall to kill the plants.