You can recognize dollar spot by the many small (1-4-inch) bleached-out spots in the turf. If it goes untreated, the small spots may expand and overlap each other. There are many other diseases that attack turf in summer, including brown patch, anthracnose, summer patch, pythium blight, and necrotic ring spot. Regardless of the disease, the treatment is the same. First, dethatch your lawn if you've got a layer any thicker than a half inch. Then treat you lawn with a turf fungicide. Finally, fertilize it. If your soil is compacted, it'd be a good idea to core aerate this fall.