A dense, vigorous lawn is your best defense.
Weeds are opportunists.
They will find bare spots or places where your grass is weak, and they will exploit them to their advantage. No matter what weeds you have, the first line of defense is preventive practices. Try these options to get at the root of the problem first, before resorting to herbicides. Preventive practices Mow high. Do not mow grass shorter than recommended for the species you grow.