I've always done them as needed and at the request of the customer. I'm really considering adding it into my program as an add on. So how many do preventative treatments vs. seeing signs and treating then?? I'm in North Carolina and with fescue the heat and humidity will breed brown patch in hours. I've yet to see a lawn that didn't have it. A nice thunderstorm like we had yesterday dropped at least 1 inch after 7 pm....so the grass was going to stay wet. With warm season grass (especially centipede) I've seen a lot of large patch in the fall and spring. I've talked with a guy at syngenta who also was a professor at my local university. We recommended 2-3 apps(2 with no history and 3 with history) for preventive care. Could I get by with 2 apps and say a 3rd may be needed at additional charge? Should I just say 2-3 apps all additional? Just trying to figure this out since a fungicide app will cost at leats $4 per1000 for treatment. The cost will add up.