I had a lawn installed in May, which brought in 2" of topsoil to a shaded lawn with an irrigation system. The lawn has been coming in very thin, and I am seeing a white fungus on the soil. The fungal bodies are a few cm in diameter, not very big and come gathered in blotches. There were a couple of slimy greyish / brown mycellial fans that showed up in some spots but I haven't seen them in a while. Any thoughts on what this could be, or how I could treat it?