If patches of crabgrass reappear after a preemergence program, what is the recommended next step?

• A. Do nothing.
• B. Apply more preemergent.
• C. Postemergence spot treatments and reseed treated areas.
• D. Remove the entire lawn.

Answer: (C)

When crabgrass has already appeared, a preemergent barrier won’t kill those existing plants. The goal is to control the active weeds with a postemergence product labeled for crabgrass and then restore the damaged turf to prevent further buildup. Postemergence spot treatments target the crabgrass that's already growing, leaving healthy lawn mostly intact, and reseeding those patches helps fill in bare areas so dense turf shade reduces future weed establishment. Simply applying more preemergent won’t eradicate the current crabgrass, and doing nothing or removing the whole lawn is unnecessary. Treat the existing patches with a postemergence herbicide per the label, then reseed the treated areas to reestablish a vigorous stand.