answer:A granular fungicide will be the best treatment since the liquids tend to wash away in rains or during watering. Your best bet is to prevent this from happening again. Do you have branches hanging low over this area preventing sun/air from hitting this patch of turf? If so, cut those back. A healthy turf isn’t attractive to fungus. Aerate and fertilize/feed your lawn at least once a year. If this area of turf has compacted soil besides aeration, you may need to ammend the soil for better drainage. University of California, Davis can assist you in identifying your precise fungus so you can choose the best fungicide to treat it.