HelpfulGardener.com

We live in South Florida. Two years ago, we had a fungus on the same area of grass I am discussing today. The lawn is being serviced by one of the national lawn spray companies. The serviceman was the one who pointed out the fungus to me and directed me to hold the sprinklers (by law, only twice a week with 20 min for each of the 3 zones) for 7-10 days. I did that and the grass came back very well.
Now, it appears that I have the same problem. But this time, in researching it, I found something called "brown patch," another type of fungus. But a gentleman to who I've used for the last few years to do yard/tree work for us said that it looks like fully dead grass in the ring and it should be dug up, allowed to dry for a day or two (as long as there's no rain) and then lay new, healthy sod.
Any advice??
Thanks,
Steve

Yeah, your St Augustine grass is dead. Sometimes you would see healthy stolons of the grass with very short leaves meaning it will recover, but I'm not seeing that. Your sedges are healthy enough. Those are the predominant green you have there. If they don't bother you, I'd probably plug the lawn with chunks of sod and put shade cloth over it for a couple of weeks.

St Augustine grows fast and builds up thatch. When it gets over a half and inch it can cause problems if it is not removed. I had more weeds and in my case since I did not know my sprinkler head was broken, I did not realize until the grass was dying that it was not getting water. I had 2 inches of thatch. So, I used round up to kill the weeds (I have nut sedge), and scraped out the dead spot and added some compost and fertilizer and used stolons from the edges of the grass and replanted it. It is slowly filling back in.