Season Long Weed Control for Lawns is an exclusive 2-in-1 formula. Post Emergent: Kills existing broadleaf weeds. Pre-Emergent prevents new broadleaf weeds for up to 6 months. One application lasts the entire season. Apply anytime Spring, Summer or Fall. Rainproof in 1 hour. Active ingredients: Isoxaben; 2,4-D; Mecoprop-p; Dicamba. Does not provide pre-emergent and post-emergent control of crabgrass.