I'm doing an experiment with unmowed St Augustine. Originally I did not think the grass would get taller than 10 inches, but it is easily 36 inches in one spot under a tree. Here is a picture I took last year. The purpose of the experiment was to demonstrate the benefits that lou mentioned above. I stopped mowing in October of 2011. The location is George West, TX on the edge of the Texas desert. Temps are above 95 from mid May through mid October with humidity running 40-50% most of the time. Since then I have only watered the grass when and where it was calling out to me for water. At no time have I watered more frequently than once per week. There is one spot under a tree on the east side of the house where I have not watered at all since 10/2011. In fact that is where the dog picture was taken. At the time it was about 30 inches high right there. Also since then I have not fertilized and used no insecticide or herbicide. As you can see there is no weed pressure at all - and I am surrounded by fields of King Ranch bluestem. There are places in the yard with plenty of bluestem, bermuda, and other weeds, but those areas are not part of this experiment. So the point of mentioning this is that taller St Aug will resist all the problems you might have with anything else. I always suggest people weld their mower at the highest position to prevent your well-meaning brother in lawn from doing you a favor and scalping your lawn back down "to where it should be." Tall St Aug (4 inches, not 40) is very lush looking and will solve your problems. Another issue you should watch for is drought stress near the sidewalk. Sidewalks take up sunlight all day and remain warm much longer that the soil under the grass. The soil near the sidewalk will get warmer during the day and remain warm until the next day. This tends to drive off the moisture through evaporation near the sidewalk and dry out the grass. The solution is to water more deeply, not more often. Generally I agree that your only problem is the grass roots are not up to speed yet. Give it another month and take another picture to compare. You should see improvement. Set your mower high, water deeply and infrequently, and fertilize and you will have a lawn like your neighbor. I prefer organic fertilizer because I am lazy and don't like to measure, but you can use chemical and get good results, too.

I don't know what you read but St Aug is very easy to manage. But before I go on, is that an oak tree buried up to its neck in soil or mulch in that picture??? That tree, oak or not, needs to be unburied so that the roots are visible on the surface. Tree bark is not meant to be buried and becomes susceptible to a fungus which will kill the tree. And yes, that looks like a disease process going on. I have been very successful using corn meal to solve my annual disease issues. The application rate is 10 pounds per 1,000 square feet. There are two problems with using chemical fungicides. One is that in Texas the temperature is never low enough to apply. The other problem is that having healthy fungi in your soil is absolutely critical. When you apply a fungicide, you can't help but disrupt the soil food web and turn your healthy soil into unhealthy soil. It also looks like you're mowing too low. What did your book tell you about mowing St Aug? And did it distinguish between sun and shade? Out of curiosity, what did your book say about watering depth and frequency?

Yup! That's the way. I let my St Aug go for 2 weeks between mowings in the summer. In the spring I can't let it go that long because it's growing so fast. Water only when needed but water a full inch when he does water. Time how long it takes to fill some cat food or tuna cans placed around the yard. That's going to be his new watering time. When the temps get back into the 80s, change from once per week watering to once every 2 weeks. This develops deep, drought resistant roots that can easily go a couple weeks with no water.

Why dont you think it's Bermuda? Tough to tell from the pic