Cornmeal, at 20 pounds per 1,000 square feet, generally works on st aug diseases.

Where do you live? I'm guessing Houston.

What is your normal watering schedule? How often and for how long do you water?

Have you gotten much rain recently? And if Houston was correct, just how much rain did you get in the past month?

I live in Houston. In the past 30 days we got 4.57in of rain. I'm using the deep and infrequently watering method as recommended by you and many others

Yeah when I asked that I realized the error of the question. We got 3 inches of rain but we got 5/8 one day, 5/8 the next, and like that. The problem was the fact that it remained moist for so long. 4.57 inches all at one time is fine, but when it is spread out over several days you get the diseases kicking in. I have had trouble with this one caused by continual moisture. You can try cornmeal, twice, and see how it works, but you might need chemicals. Or you can leave it alone and the winter should take care of it. Is it Floratam in full sun? If so it should slowly take care of itself.