If you cannot find anything, then treat for fungal disease. It is too hot in Houston for chemical fungicides. If you want to try an organic approach, find a feed store that sells ORDINARY corn meal (not corn GLUTEN meal) in 50-pound bags. Price should be about $15/bag this year. The application rate is 20 pounds (minimum) per 1,000 square feet. Apply again in 3 weeks. If you have already applied a chemical fungicide, sulfur, or baking soda, then the corn meal approach will not work against the disease.

Corn meal does not kill fungus disease. Corn meal decomposes on the soil via many species of microbes. One of those microbes is another fungus which is predatory on fungi. When you apply corn meal, within about 2 weeks the killer fungus is on the job and will kill the disease fungus. By applying again you ensure the killer fungus will be around plenty long enough to stay after the disease. Good news is that corn meal is also an organic fertilizer, so your remaining grass should turn a very dark green in 3 weeks. You can apply it any day of the year without fear of harming anything.

Okay so why do you have the disease? Because you have been watering every day. As Texas Tifway said, it is a common mistake. Quite often the sprinkler installer will set up the system to impress the new owner with all the capability. There are many reasons why to water once a week. Without getting into all of them, suffice it to say there is no good reason to water every day.

Your grass will have to be weaned off of the daily watering. Daily watering develops short little roots. If you went cold turkey with once a week watering, you might lose the remaining lawn. I would skip a day and see how the grass looks. Then on the next watering, water for twice as long and skip two days. Also I would set up the watering system to shut off while I am awake in the morning. That way you can look outside and see if there are any broken sprinkler heads. I walk my dog at midnight and it is not all that uncommon to see broken sprinklers that the owners never know about.

Everyone's watering system is different. Mine waters very slowly. It takes 8 hours to get 1 inch of water (as measured by tuna cans). Thus I normally water once a week for 3-4 hours per zone. That is usually good for 10 days but with our watering restrictions, there is no provision for going off of weekly watering. How long I water depends on drying winds from the west. I'll go up to 7 hours if I need to just to keep the grass from dying in a week. But some neighbors have a system that will put down an inch an hour. Everyone's is different.

Thinking more about the chinch bugs versus disease. Can you take a close up of the grass near the edge of the brown areas? I'm looking for yellowing and/or spots on the grass blades. In any case, find some corn meal. Call around. Careful because lots of feed stores are selling corn GLUTEN meal but not all sell ORDINARY corn meal. They are different. Cracked corn would work as well. Corn is always going to be a good thing for your soil and grass.