It sounds like you are getting information from all over the place. The big hint was applying gypsum. Unless you know from a soil test that your soil is acidic, then you should not be thinking of adding gypsum. Generally Texas soils are already too alkaline. Why do you want to aerate? Do you think the soil is compacted? Does it feel hard when you walk on it? Does it feel soft(er) when it is wet from rain or irrigation? If the soil feels hard when dry and softer when wet, that is perfect. If it feels hard when wet, then you could aerate it and that might help. If you do go ahead and aerate, then it sounds like you have done your homework. Aerate a lot more than you think you should. While you are at it, if you have high spots that you would like to lower and low spots you would like to raise, then hit the high spots harder and sweep the cores into the low spots to melt back into the surface. Generally you should keep the St Aug tall but if it is 4 inches high, that makes sweeping cores more difficult. A really good alternative to core aerating is to spray liquid soap on the lawn. I hang out in other forums (which Gardenweb does not allow links to, for understandable reasons). In one of those forums they have developed a tonic (shades of Jerry Baker) that really does help soften your lawn. I tried it last year and it worked great for me. In fact it is still working for me. The idea is to break the surface tension in the irrigation water and allow it to soak down farther into the soil. Then that moisture down low holds the moisture content up higher for a longer time. The explanation drags on much longer but the bottom line is the soil is a lot softer. Okay, the mix is just soap. Their tonic is a mix of aloe vera juice and a special soap, but they make that stuff by the 5-gallon pot. I just sprayed generic baby shampoo through my hose end sprayer. Adjust the spray so the stuff coming out looks slightly foamy. Then spray. Following the spray you can irrigate. If you do this right before a rain, then you don't have to irrigate. Repeat in 2 weeks and again 2 weeks after that. That's all there is to it. I believe the soapy spray will save you the expense and hassle of the core aerator. The key to choking out bermuda is to make the St Aug as dense as possible. For that to happen it needs water once a week in the heat of summer, tall mowing (highest setting), and fertilizer. I use organic fertilizer (corn meal specifically) so I don't have to worry about when I fertilize. With synthetic chemical ferts, you should not fertilize after Memorial Day. In Houston even Memorial Day is pushing it for the heat. If you decide to really go for it and want to make it as dense as possible, you can apply any organic fertilizer at a rate of 10 pounds per 1,000 square feet every month. 10 pounds is the lowest amount that makes any sense. If you really wanted to make an impression, go to 30 pounds per 1,000 every month, but that is almost asking for lawn mower problems. Pushing a lawn mower through very dense St Aug can be a chore. If you want to apply compost, the application rate is 1 cubic yard per 1,000 square feet. NO MORE! Even that can smother your grass if you don't sweep it in with a push broom. Any grass that remains buried after you finish with the sweeping will not return, so get all those blades up and all the compost under the grass blades. Compost is the most expensive thing you can apply to a lawn. While it is good, I think it is over hyped. I would MUCH prefer to spend that money on organic fertilizer rather than compost. The bang for the buck is about 100x better with fertilizer. You did very well in giving enough info. Thanks for doing your homework.

Bermuda Bible, which says that common varieties can be mowed to between 1-1/2 and 2 inches. At those heights, will the same 2-3 times per week frequency be required? No. The rule of thumb for mowing any grass type is to never remove than 1/3 blade length. Many if not most of the Bermuda hybrids and even some of the improved common varieties can be maintained at 1/2 and less with some of the dwarf varieties. If kept that short requires mowing every other day. Bermuda grass very fast, so fast under the right conditions you can dang near see and hear it grow. When kept at say 1.5 inches you would be looking to mow every 5 to 7 days, and under some conditions, wet and warm, every 3 to 4 days. What results from less mowing? Seed heads? Thinning? Correct. Bermuda has a unique characteristic in that it can be trained to do something no other grass can do. Some expert says it is self defense. When kept short and mowed frequently the blades learn to lay low and grow horizontally to avoid the blade. When this happens the grass interweaves into a tight dense mat of carpet. It forms a barrier weeds have difficulty breaching. As the maintenance height is raised allows the grass to grow more vertically, which loosens up the density and opens the canopy so to speak. It begins to thin out which opens up more opportunities for weeds to invade. I don't mind the fertilization schedule. I'll be going the organic route, so I'm thinking soybean meal, CGM, or alfalfa pellets once per month. Any opinions about which one of those will be best for Bermuda? Also, given my organic care leanings, will general good Bermuda practices eventually crowd out the fescue? If you are going to go the organic route for economic-technical reasons I would suggest Milorganite over the feed-grains. Of the three you listed Soy Bean Meal would be #1 choice. CGM is great but very expensive and SBM has about the same protein content. Alfalfa pellets are uselees on Bermuda, as is corn meal. FYI Bermuda is a nitrogen hog, and many if not most of the organic alternatives cannot supply enough nitrogen fast enough to meet the demand early on and may take a season or two to build up the soil microbes to digest the food grains. However Milorganite works pretty much just like commercial fertilizers. IT has slow release nitrogen but not painfully slow and has some iron in it which is welcomed in any lawn. Now with all that said consider this. For the first season to kick start the Bermuda growing use a commercial slow release urea fertilizer for the next 2 months. Then 1 half application commercial urea, and half organic choice.

The only way you can know about your sprinklers is to put out tuna or cat food cans and see how full they get as you water. It takes 8 hours to fill on my yard but only 20 minutes to fill on my neighbor's. Everyone has to do this if they want to know what it means to water 1 inch. There are low flow sprinkler heads. A friend in Phoenix has soil similar to what you described and solved his problem with shampoo (see below) and the low flow heads. These heads are gear driven and send out a small stream of water on a rotator. Of course he waters a lot longer but the same amount of water hits the soil. You definitely don't want runoff. That's just wasting the water. You can try applying 3 ounces per 1,000 square feet of any clear shampoo right before you water. I have used the generic baby shampoo from Wal-mart as well as Alberto Vo5. Both are pretty cheap solution to the water penetration issue. The soap will allow the water to penetrate deeper. Apply it once now, water normally next week, and repeat the shampoo in 2 weeks. Don't use dish soap. Shampoo is used for a reason. When you see runoff, turn off the sprinklers immediately and let the moisture soak in for 20 to 30 minutes. Then try to get the rest of the inch of water into the soil. Palmetto is semi-dwarf. 3 inches should be good. Yes, the grass will all come up to that height. That will really help with the bermuda control. St Augustine works by using its coarser blades to put more shade onto the bermuda grass until the bermuda is completely shaded out. One flaw in this plan is the Palmetto has finer blades (less shade) and it likes being shorter (like bermuda). I've had pretty good success taking my lawn back from bermuda, but I have common St Aug and Floratam. Tall grass getting more fungus? Not that I've noticed. I have a second yard at a house in George West. It is a large yard with Floratam ranging from 12 inches high up to 32 inches and no signs of fungus that I've noticed. Here is a picture. That grass is about 18 inches high.

I was thinking the same thing. You can't get rid of bermudagrass without killing the St. Augustine. The good news is the St. Augustine stolons grow a half inch a day in the summer. So killing the yard and starting over wouldn't take long. You say the front yard is nearly perfect so in the perfect areas use some of your yard as a nursery and plug the back. The front will recover quickly and the back will soon be looking as good as the front. The key is using the top labeled amount which could range from 3 to 5 ounces per gallon. Then to use it as soon as you can then in about 2 weeks. You should have pretty much wiped out the back lawn. I would then cut the grass as low as possible then plug all you can. Keep it well moist and then wait. I would think by the end of next year you should have a solid back yard. Good luck.