i've read this somewhere, that mulching leaves into the lawn, will act as a natural herbicide. didn't give it much thought. but check this out, like 2 yrs ago i started using doubles, which meant i started mulching alot of the stuff back into the lawn. there are certain lawns that would always require 2 blanket apps of herbicide, as well as spot spraying throughout the season for crabgrass and broadleafs. not that there were major weeds, but on some we aim for totally weed free. i noticed something this past season, the lawns that needed this constant attention for weeds, needed only one blanket app this season, and no spot spraying, and they were virtually weed free! could there be a connection?