Control and prevent poison ivy, poison oak, and more with Poison Oak & Ivy Killer Ready to Use Spray. This fast acting formula starts working to kill down to the root overnight. Effects begin to show after a few days as weeds gradually die. Product is rain proof within 6 hours of application and will not wash away. When used as directed, this product won't harm wanted lawn grasses. This product arrives conveniently ready to use with no mixing or pouring required. To use simply aim the trigger sprayer bottle where weeds are actively growing and spray. For best results and for full use instructions, please see product label.