It depends on what you will be happy with. If you stick with the St Aug you will have one type of grass to deal with. If you mix in bermuda, then you will have a weedy looking lawn. If you buy a bag of cool season grasses (rye, fescue, and/or Kentucky bluegrass), then those will all be dead by July. They cannot handle the heat down here.

I assume your budget limited the purchase of enough St Aug to cover the entire area. It will spread and will spread especially well when mowed at least 2 inches high. I've had great luck with it spreading at 4 inches. Now is the time is spreads. It will take the summer off from spreading and spread again in the fall. Total is about 10 feet per season.

Your grass started dieing near the curb because the curb holds heat from the daytime and dries the soil out all night. Those areas are much drier than the interior areas of the lawn. The rest probably died from watering improperly and may have been helped along by mowing way too short. I watered my lawn once a week according to the San Antonio Water System schedule, fertilized heavily with organic fertilizer, and skipped mowing every other week (or two). The lawn never looked better.

Watering
I have not watered my lawn in San Antonio yet this year. Then again I am on my way there after being away all week so I might be watering today. When I water I apply 3/8 inch all at once. BUT THAT IS MY LAWN. I thought my sprinkler put out a lot more water than it does. It takes 3 hours to apply that much all at once. For you I would start at 1 full inch. Use a cat food or tuna can to measure. Time how long it takes to fill the can. Apply all that at one time for the areas where your sod is intact. For the new sod, you'll have to water that daily or with the soaker for 2 more weeks. But then back off on frequency. Daily watering for just a few minutes will give you weeds and possible dead grass if you miss a day.

Mowing
Mulch mow at your mower's highest setting. Weld it in place so someone does not come along and do you a favor by cutting it down short. In the heat of a really hot summer (routine daily temps in the 100s) you should skip mowing every other week until the temps fall back into the mid 90s. Long St Aug does much better in the heat than short St Aug. At the end of the season, there is no such thing as a "final mow" like you hear about with other grasses.

Fertilizing
I would strongly encourage the use of organics. You can do things with organics that would kill a lawn on chemicals. For example you can fertilize every month or every week and not hurt anything. The grass just does better and better. If you are curious about that, go to the GardenWeb Organic Gardening forum and find the FAQs. The Organic Lawn Care FAQ is near the bottom of the list. Read that for more information. That is the plan that has converted hundreds if not thousands of chem fert users over the past 8 years. If you decide to do that, I have a suggestion or two to tune that up for 2012. If not, then fertilize with chemicals sometime in May. Memorial Day is easy to remember but that is getting a little warm. Then don't do anything but water and mow until Labor Day. Fertilize again then and again on Thanksgiving.

What part of the county are you in? The soil to the SE is more sandy and the soil everywhere else is limestone.

And for those of you reading from outside Bexar county, the X is silent. It is pronounced like the animal, bear.

Well, lot to chew on here. I'm just a few miles SE of 1604N and 281. My front yard is clay based topsoil, pretty deep. The front lawn is divided by the driveway, with unshaded areas near the curb, facing west. The grass died only on one side. It kept dying back, towards the house, for a couple of months after I became alarmed, and started watering it heavily. I did some digging, and turned up no destructive worms or insects.

I've always had bermuda near the curb, and it gradually gives way to St. Augustine, coming back towards the shade. I'd kind of like to keep it that way. I thought I might sow some in the bare areas, where it got crowded out by the St. Augustine, just to avoid patches of bare dirt.

I have mowed for years with a mulching mower with the blade at the highest setting. I'll have to study on this grass "mix." Those bare areas are going to look even more awful, soon as the wind blows the leaves away.

Are you in that low area that crosses Bulverde at Jung? That is one of the few places in town that is not limestone.

If you are familiar with, and happy with, the bermuda/St Augustine mix, then stick with it. I have that at my driveway at a house further south. I'm trying to see what I can do to get the St Aug back in there. I also have King Ranch bluestem to contend with. That is the tall grass you see growing in the highway medians all over Texas.

You said you watered it heavily. Can you describe what you did?

Rake your leaves away. St Aug is easily smothered. After 20 years of tending my lawn in different ways, I have come to the conclusion that the live oak blanket of leaves is there to prevent grass growth under the trees. Rake them out of the soil. You'll be shocked how much you get. I get bushels and bushels.

I can't overemphasize the benefit from proper watering. You are already mowing right. Then it comes down to fertilizing to get it dense and spreading.

Thank you sir. I'm in Green Spring Valley. I think a lot of dirt was hauled in to level my lot, topsoil in front (to 14") and caliche in back. I've got a sprinkler system and, when the grass started dying, started supplementing the water with a soaker hose. I had been soaking it good once a week, the same way I had been doing for 20 years, with no problems. That soaker hose may have been oozing more water than I thought, and I could have overwatered. The problem area is away from the trees, and doesn't get many leaves. I've been mulching them with the mower. There was no mat of leaves under the dead grass, when I brushed it away. The shady areas, which get most of the leaves, appear to be doing well.

I've never fertilized, because the lawn always looked decent without it. I have a neighbor who is always spreading or spraying something on his yard and, until last year, you could hardly tell the difference between his and mine. (Obviously, I'm not shooting for the cover of House and Gardens.)

Green Spring Valley - that's the place. I think they had to raise the level in there to build the subdivision so it would be out of the creek flood plain. Your soil is unlike any other in town. You might be able to go longer between watering than the rest of us with the limestone soil. I'm wondering what your pH is in there. It's probably still 8 but would be good to know for sure. The other concern I would have with that area is the reduced amount of wind from being in a lower area surrounded by hills and houses. Lack of air circulation is a problem for St Augustine; however, usually the circulation problem is a highly localized - like if you piled up yard clippings on the lawn. Just doing that will kick off a fungus in less than a week. Do you remember piling up clippings for the city to haul away last year before this started?

Last summer was a stressful summer for most lawns in the area. I believe your problem was a disease. You have ruled out every other possibility. You're doing everything right and you checked for bugs. The only thing left is disease.

How is your new sod doing in the areas where it died last year? Does it look great or is it thinning out? If it is thinning out then you still have the disease in the soil.

Fungus was high on my list of suspects. I never stack brush on that side though, because of the mailbox. There was also some die-back in the lawn to my left and across the street, but nothing like I had. The rest of it's looking pretty good, including the back, and the pieces of sod, which went down 3/24 are dark green and putting out new growth. No weeds yet, knock on wood. Just wish I could do something with those bare spots (other than haul my rear out there and sod the rest of it), but I've got a deck to rebuild, and sprinklers to replace and. . .you get the picture.

That's good that the new grass is thriving. You'd know right away if there was disease in the soil. I'd leave well enough along if you can't add more sod. I assume you got your sod from Milburger's since it is about a mile away. That's where I get mine when I need some. Floratam Friday!