Blackberry bushes grow by sending off shoots from the main plant through the soil. These offshoots or nodes will eventually grow into new blackberry bushes. To remove the bush, the Oregon State University Extension Service recommends using an herbicide that contains triclopyr or cutting back the plant and digging up the root and nodes of the bush. If you are vigilant with your preferred removal method, you will be able to destroy and remove the blackberry bush.
Mix the fertiliser according to the instructions. Fertilisers with triclopyr will be clearly marked for bush control.
Spray the fertiliser onto the plant. It is necessary to wait until the time is right to apply the fertiliser. Spraying the fertiliser on the plant while it is dormant will not destroy the plant. The fertiliser must be absorbed by the plant and spread throughout the roots. Time the fertiliser application between the last of the fruit but before the leaves begin to drop.
Allow the bush to turn brown and wilt. Dig the dead blackberry bush out of the ground using the garden shovel. Make sure you remove all of the roots and shoots.
Dispose of the dead bush and nodes. Do not place the bush into an organic compost pile. The residue from the herbicide may remain with the plant. Call your local yard waste collection facility.
Cut the bush branches with a hand saw or chain saw. Leave only the stump exposed.
Dig out as much of the stump, roots and nodes as you can with the shovel.
Use the tiller to till the area. Turn over all of the soil in this area. Rake the loose pieces of bush up from the ground.
Watch the area closely. Use the garden tiller anytime you see new shoots appearing from the ground. This may take several attempts to remove the entire bush.
Grow blackberry bushes in containers to control growth and for easy disposal.