Ortho GroundClear Poison Ivy Tough Brush Killer, 32 oz. Concentrate. This fast-acting herbicide kills poison ivy, poison oak, wild blackberry, and over 60 other listed tough weeds and brush. It starts working immediately, producing visible results in just 1 hour. The formula works systemically, killing weeds right down to the root. Apply to leafed-out and actively growing weeds in non-garden areas around homes, cabins, buildings, fences, and trails. Active ingredient: Triclopyr, Triethylamine Salt: 8.0%.