QuickSilver is tough on broadleaf weeds, it is gentle on a variety of grasses including Bermudagrass and St. Augustinegrass, even in newly seeded, sodded or sprigged areas. Carfentrazone-ethyl, the active ingredient in QuickSilver herbicide, is one of the most environmentally sensitive herbicides available. It does not impact birds or earthworms and is unlikely to harm honeybees, predators or parasites.