Roundup Poison Ivy Plus Tough Brush Killer2 is the easy way to control plants around your yard. Its exclusive formula works to kill poison ivy, poison oak, poison sumac, wild blackberry, kudzu, and all types of tough weeds to the root. In addition, it is rainproof in as fast as 30 minutes, produces visible results in hours, and allows you to plant 1 to 30 days after application.