Sumter County Extension Office ? Solutions for Your Life - UF Institute of Food and Agricultural Sciences
You can guess or you can find out for sure. On Monday between 9 AM and 3 PM master gardeners hold a free plant clinic at the Sumter Annex on 466 & Morse Boulevard.
Take pictures of your grass, noting whether your irrigation system is reaching that area of grass, and if it is too dry or too wet, cut a sample of the grass and take it with you to the plant clinic. If they are unable to determine from looking at the grass whether you have a pest or a fungus or an irrigation problem, you can pay a fee to have the grass sent to University of Florida for analysis.
Treating a problem first requires identifying and diagnosing what the problem actually is.