Quinclorac, Dithiopyr, Dicamba and 2,4-D all combine to kill many different kinds of weeds, at many sages of development, but what makes this product unique is that it is the only effective post emergent crabgrass killer currently available for home lawn use, and timing applications for good results is no longer necessary. Formulated on a light carrier for better leaf adhesion and effectiveness. Treats northern and southern lawns (not Centipede grass or St. Augustine grass). Rates as low as 2.4lbs./1000 sq. ft.