Any spraying we do early, especially on new customers really cuts down on spraying in the later rounds. The first week we are out (around the 1st of April) there are not weeds to spray, however the other 5 weeks of our round one have weeds growing. Not all weeds are annuals. Yes pre-m does something for weeds (cuts down on annuals) but does nothing for perrenials. If you don't spray creeper starting round one its hard to get under control later. We use oil based weed control when cool and water based when warm. If we waited till round 2 to do weed control, we would have to wait till fall to use T-zone. T-zone works on violets and its too warm to use it round 2 (volitization). We are the only company in the area that controls violets and like that.