|As you clear a section, go back and paint fresh-cut stumps with concentrated brush remover, using a plastic cup with a paintbrush. Wear chemical-proof gloves and keep the concentrate away from desirable plants. Working in sections, continue to clear canes, going back to paint the stumps. For best results, paint each stump within ½ hour of cutting. As necessary, repeat this treatment at once or twice a year; large, entrenched blackberry patches will regrow, although much reduced in vigor. With determination, however, the patch will eventually be eradicated.