Here in NC we get up leaves on a regular basis just like mowing during the season. My last app on fescue comes around thanksgiving with a app of fertilizer and weed control. How effective is a herbicide on a lawn that has leaves? I would think I could get 25-50% coverage on target weeds with the rest being covered by leaves ...if I haven't already vaccumed them up that week. Is that enough for a contact herbicide to work?