If you have to cut the grass, use a grass bag on the lawnmower as when you cut them you spread the spores. Now is the time to visit you lawn & garden store and get fuguscide and follow the directions on the package. Wear appropiate long clothes, gloves, mask, goggles & hat..........Keep children & pets away until it is dry. If it is going to rain or it's windy don't put it down. You will need to treat again in the spring and does this area have proper drainage or was there a tree there at one time years ago? Fungus feeds on dead roots, and very old mulch. Don't mulch anything from that area...You are going to have to bag & trash.