Several preemergence herbicides will control crabgrass in established lawns. These include benefin, bensulide, and pendimethalin. Often these herbicides are combined with a turf-type fertilizer. This allows the gardener to apply a preemergence herbicide and fertilizer with one application. This herbicide effectively controls crabgrass without affecting the germination of the turfgrass seeds.
Gardeners can also control crabgrass by applying corn gluten meal.
A corn milling byproduct, corn gluten meal inhibits the root growth of crabgrass seedlings. Unable to develop roots, the crabgrass seedlings die. In addition to crabgrass, corn gluten meal offers pre-emergent control of dandelion, plantain, lambsquarter and other weeds. Products containing corn gluten meal are available at garden centers and mailorder companies. The keys to successful control of crabgrass in lawns are correct timing of the preemergence herbicide application and proper application of the material.