Prodiamine 4SC Select™ is a pre-emergent herbicide that provides residual control of many grass and broadleaf weeds by preventing growth and development of newly germinated weeds. Weed control is most effective when Prodiamine 4SC Select™ is activated by at least 0.5 inch of rainfall or irrigation or shallow incorporation (1-2 inches) before weed seeds germinate and within 14 days following application.