Answer: No chemicals will control it while it is actively growing. However, crabgrass seeds need light to germinate, so any problem that results in open areas in the turf (disease, insects, mower scalping, poor fertility, etc.) will enhance crabgrass infestations. Maintaining short turf also favors crabgrass - higher mower heights (in the 2 ? - to 3-inch range) can help shade the soil surface and provide competition for crabgrass. The best competition for crabgrass is a thick, healthy lawn. So if you want a nice green grass (not crabgrass) lawn, concentrate on the grass. Keep it well-fertilized according to the results of a soil test, seed any bare spots, and set your mower blade higher. Early next spring apply a pre-emergent herbicide and by this time next year you should have a crabgrass-free lawn.
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