Tackle grassy weeds in your yard with Roundup for Lawns Crabgrass Destroyer2. This weed control product kills crabgrass and grassy weeds including barnyard grass, foxtail, goosegrass, johnsongrass, panicum, millet, shattercane, and others as listed. In addition, this grassy weed killer may be applied before seeding, including the day of seeding (do not apply for 28 days after seeding of listed turfgrasses). Use this product on Kentucky bluegrass, fine fescue, perennial ryegrass, and tall fescue. To apply, remove the sprayer and pull the cord all the way out. Insert plug into the knob opening on cap. Flip up the spout or turn the knob to ON and adjust the nozzle to the desired spray setting. Weeds will turn white 4 to 7 days after application and whither before dying. For best results, apply to actively growing weeds during early growth stages. Do not apply to bahiagrass, bermudagrass, buffalograss, carpetgrass, clover (desirable), creeping bentgrass, dichondra, St. Augustinegrass (including Floratam), seashore paspalum, or zoysiagrass. Do not irrigate or apply if rain expected within 24 hours of applying. Do not reapply this product within 3 weeks of first application.