Roundup for Lawns Crabgrass Destroyer2, Ready-To-Use, 64 oz. This weed control product kills crabgrass and grassy weeds including barnyard grass, foxtail, goosegrass, johnsongrass, panicum, millet, shatter cane, 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. Weeds will turn white 4-7 days after application and whither before dying. For best results, apply to actively growing weeds during early growth stages. Do not apply to bahia grass, bermudagrass, buffalo grass, carpet grass, clover (desirable), creeping bent grass, dichondra, St. Augustine grass (including Floratam), seashore paspalum, or zoysia grass. Do not irrigate or apply if rain expected within 24 hours of applying. Do not reapply this product within 3 weeks of first application.