BROAD-SPECTRUM WEED CONTROL: Tenacity herbicide is a liquid lawn weed control solution labeled to control 46 broadleaf weed and grass species, including crabgrass, goosegrass, clover, dandelion ...

One reviewer noted that Preen isn't a crabgrass killer but a preventer. The implication is that this product, even as a sometimes post-emergent treatment, isn't meant to deal with a lawn full of ...

While this post-emergent is safe for some grasses ... concentrations of the herbicide to treat crabgrass compared to broadleaf weeds, and total control may require a few applications.