is quinclorac a post emergent
Active Ingredient. Quinclorac 75 DF Herbicide (Crabgrass Killer) Quinclorac 75 DF Herbicide is comparable to Drive XLR8 and is the best crabgrass killer available. Quinclorac is a post emergent crabgrass control product meaning you can spray it on actively growing crabgrass to stop growth and eventually kill it.