And so does your ground water, your neighbor’s ground water, and the the size of your children’s future gonads. Would you pour herbicide on your head?
Proper irrigation, fertilization and maintenance will ward off most fall weeds in your lawn. Using a mulching mower and returning clippings to the lawn can add nitrogen. Don’t freak out, clippings will not contribute to thatch as long as mowing occurs on a regular basis.
Perform fall aeration between August & October, during peak shoot growth, so your lawn recovers quickly from coring. Do not renovate or aerate past late fall. (Both renovation & aeration of lawns should take place in the late spring or early summer when the turf is actively growing.) Avoid any winter damage by reducing or eliminating irrigation early enough in the fall to allow the warm-season turf plants to harden off.
Don’t forget, the final late-season nitrogen application should be applied no later than six weeks before the first expected frost date. Use corn gluten meal, molasses, seaweed, or any fish emulsion-type things to crank up a little nitrogen. That corn gluten meal will actually pack down & give a nice alternative ‘pre-emergent’ for the fall. Organic options are now not only lawn-loving, they’re actually fashionable.