Syngenta says you can protect your cool-season turf, including newly-seeded turf, from 46 tenacious weeds like crabgrass, ground ivy, clover and nimblewill with its Tenacity herbicide. Tenacity removes weeds from established turf and can be used at seeding to prevent weeds from germinating in newly seeded or overseeded turf so your seeding investment is protected from the start. You can use Tenacity when overseeding in the fall, converting bare areas to turf, or removing grassy weeds from the lawn. Once applied, Tenacity translocates throughout the weed and terminates growth within two to three weeks. Soon after application, weeds stop competing with the desirable turf as photosynthesis is disrupted.