Brown patch lawn disease, or Rhizoctonia blight, is a fungal disease that mostly occurs in areas of high temperature and increased humidity, usually during summer and early fall.
It's characterized by a distinct pattern: a circle of brown grass on the outer ring with yellow grass inside. Occasionally, the inner grass can return to its original green shade.
To mitigate the disease, water your lawn early in the morning so that excess moisture can evaporate by midday, and consider aerating your yard every other year.
One of the most effective preventive measures is to apply a fungicide before the disease takes hold. If not, you'll have to wait for the infection to subside as humidity decreases.
Lastly, while fertilizer can enrich the soil with essential nutrients, it's important not to overapply, especially during the summer months, to avoid exacerbating the disease.