You put FOUR INCHES of water on your lawn every week? Eeeek! For one thing, whatever fertilizer got put down is probably dissolved and in your deep water table. You're probably leaching it out. I'd just wait until the grass looks thirsty before applying water. Half an inch should be plenty. I think the standard test for proper watering is if the soil six-inches down is moist. Sounds like you're irrigating down to a few feet.

Did you scalp as low as you could go at the beginning of the season? If so, you may just need to bump the blade up a notch to get more green leaf on top. It needs a bit of extra leaf in the extreme heat...

No, that's not what the A&M extension site says. See here.

http://publications.tamu.edu/TURF_LANDSCAPE/PUB_turf_Maintaining%20Bermudagrass%20Lawns.pdf

It says "to keep your lawn healthy, water it only when the grass needs it. When you do water, wet the soil to a depth of 6 inches. Don’t water again until the grass shows symptoms of drought stress—a dull bluish color, rolled or folded leaves, and persistent footprints." That's NOT putting on six inches of water. Six inches of wet soil is not six inches of water. Not even close. That might take 30 minutes of sprinkling, they say. Their writeup is a little confusing, because after you wet the soil to a depth of six inches, they say you should have set cans out to see how much water you've deposited. I believe that's so that once you wet the soil to a depth of six inches, you know how much water you need to put on to do that next time.

You've probably leached all your fertilizer out, and you might just have root rot from submerged roots.

When I measured using a tuna fish can it took about 20 minutes to get 1/2 inch of water in the can, which penetrated to about 3 inches.

If you want to penetrate to a depth of 6 inches one inch of water is needed. Do you think you might have misinterpreted the directions?

Guidelines for lawn watering in central Texas

"LAWNS: Creating a deep root system is probably the
single-most important goal during hot weather. Lawns should be watered
to a depth of 6 inches during each irrigation. To calculate the
length of time to run irrigation, collect several empty tuna fish cans
or cat food cans and set them randomly around the yard. Run the
irrigation for the length of time you are used to running it. Check the
amounts of water collected in the cans and calculate the average
amount. Next, dig down in the soil to see to what depth the water
reached. Now you can calculate any adjustment that might be needed in
water time. Let’s say you collected an average of ½ inch of water in
the cans in a 15 minute time period, and the water penetrated the soil
to a depth of 3 inches. You can now calculate that it would take
approximately 30 minutes, or 1 inch of water to penetrate to a depth of 6
inches. Sloped yards may need this amount applied in two time periods,
an hour or so apart, in order to slow down run-off on the slope. Soil
depth and type plays a roll in water percolation rate."

Come on people it's Bermuda, which means NOT a water issue. Unless the grass turns blue (and I mean legit Blue) it's getting enough water.

Sure, give it more fertilizer. It won't mind I promise. Bermuda loves nitrogen. I don't think that's the issue, but go for it.

Search for a few of my old Bermuda posts, I've addressed cut height & beginner maintenance a couple times before & it's easier than most people think

reeljake, the issue is not whether it's getting enough, the issue is whether she's flooding it and washing nutrients away or causing disease issues.

I suspect the OP is new to Central Texas, because this is not a heat wave - this is summer. We're having a spell of arid air which gets warmer in the day and cooler at night. The low humidity does suck the moisture out of the soil, so it definitely affects the watering. In my corner of Texas we got 3 inches of rain 2 weeks ago. That was a Monday and my watering day is Tuesday. So I skipped that following Tuesday and last Tuesday. It is looking dryish now so we will water tonight.

I usually disagree with the TAMU recommendations for lawn care. This is another example of that. They take a relatively simple concept and obfuscate it. Who really digs down into the soil after watering???? Seriously! I also disagree with averaging. If you average it you will end up with dry spots that may become dead spots (not with bermuda). Everyone knows what I advocate, but I'll summarize for the OP. Put out the cans and TIME how long it takes to FILL them ALL. That is your watering time. In doing this you may see that some sprinklers need to be adjusted for more even coverage.

You drowned your lawn, and that can lead to all kinds of bad stuff happening to it. But Bermuda is awfully hard to kill, so it'll come back when the conditions are right. I'd let it dry out completely, which will kill the fungus and probably also the tops of the grass, but the roots will be fine, and will reemerge in time. Yeah, I'd just ignore it for a few months.

Agree with dan. You need to stop watering altogether and chill. It is a very rare event when bermuda gets a disease. It's almost as rare as bermuda dying. You can't blame bermuda fungal disease on weather in Texas...unless it's one of those national news weather events that lasts for 5 days without moving. We had one of those back in the early 2000s.

I don't know what watering less and more frequently means to you, but if you ever water more than an inch once a week in the summer, then you are over watering. TAMU has about the worst advice ever. When they say to do something I usually end up doing the opposite.

i agree with not watering. Bermuda is amazingly resilent and it will establish deep roots if not watered.... mine did, and my yard man said we had the most beautiful lawn.... he said... believe me....I see a lot of lawns! I told him,,, i don't water!

Was this yellow patch or some other fungus?