I have already used a premergent, but still have young crab grass coming up through my lawn. If I am persistent, will just pulling out the new leaves weaken and eventually kill the new crabgrass, or do I absolutely have to dig up the roots through my lawn?
Crabgrass is an annual plant so, if the seeds of this year’s crop are sprouting in your lawn, they would be tiny with only a tiny blade or two growing this early in the season. If you have a larger clumping grass growing and spreading this early, it isn’t crabgrass. Crabgrass preventer prevents the seeds of crabgrass from sprouting but it won’t do anything to stop perennials plants including undesirable perennial grasses. Digging out the roots is the best option other than killing the area and reseeding it.