Brown patch. If you cut your own grass, get your blade and under carriage cleaned up and sanitized. If a crew is doing your lawn, you will probably see this problem most of the year. Good luck.

Home depot has a product called Bioadvanced and it contains propiconazole. They also have the Scotts granules with the ingredient called carbamic acid. Both are for fungus but don't know if they will work.

It could be take all root rot, cinch bugs could be but its not hot and dry enough for them. Corn meal will do the trick.

Water only in the morning and not at night to prevent brown patch.

Grubs leave a plate sized circle, fungus will leave large dead patches and is also spread by your lawnmower blade and wheels. Get on it soon with anti fungul spray or home remedies and wash your lawnmower tires and blade. Avoid pushing your mower thru the dead patches.

Correct, but mother nature has been watering around the clock for weeks in NTX and doing it again right now

I agree.

Only warning about cornmeal is that -if you have wild hogs in your area- they will come calling to it. My neighbor treated his St. Augustine liberally with cornmeal a few years ago and a few weeks later, feral hogs hit it and it looked like it had been plowed with a tractor. Caveat emptor!

I have an area like that but it was due to water standing and then freezing during the Feb Ice Age,

Could be the problem.

right...4 tsp of baking soda per gallon of water, it works..

I have nearly perfect St. Augustine all over except one spot. It looks like that but worse. My spot is near where I killed a China Berry stump 6-8 years ago, where my 'coon infestation pooped and peed in 2019, and where my back yard gets the least sun. Mine is fungus with ongoing chemical imbalance issues in the soil I think. I will likely do nothing. Pics are of my one spot and an example of the rest.

If fungicides don’t work try an inch layer of peat moss. The acidity works well on this. Also when watering the yard start around 5am or later. With the warmer nights watering in the evening will greatly increase the chance of fungice, brown patch an take all root because the soil stays wet all night long. These are all related to St. Augustine grass.

Time to start over.

That bottom pic is beautiful

I can still see some brown in there.