Oops... The guy that does the fert for this lawn (not me!) usually leaves a little sign in the lawn, but I guess he didn't today. He had sprayed with tank and hose the whole lawn, preemergent/fert/broadleaf mix. Customer called me and said they found his sheet of paper giving all the details, in the door at noon and took it in. I showed up about 1:00 after they had left again. He said he saw me mowing down the road but didn't think about it hard enough to realize that I may have mowed theirs today too. Certianly not good. Spray application was still totally on the grass, and I'm mowing pretty low for the first cut! I'd bet I removed 75% of it if I had to guess. Lawn is very thick, most of it had to be stuck in the tops on the turf. This is WHY I like to be able to do all the fert/weed control on all the lawns I mow, this kinda crap dosn't happen that way!