Dry or diseased St. Augustine?

Hi guys, Need your help. I live in Texas. Most of my lawn looks beautiful except an area in the backyard. The area is about 10 feet in width and looks very dry. Is is just dry grass or a disease? The grass gets 100% sun.
Here is a little history on the grass: - St. Augustine grass (brand new home) installed in january - sprinkler system installed in mid april -about end of may/beginning of june we noticed that the grass in this particular area (as well as other areas) was looking silvery and leaves were curled in. we increased the water. MOst areas recovered except this particular problem patch. - about 2-3 weeks ago when we had rain almost all week, that patch of problem grass looked greener and healthier for a few days. Then, it went back to looking dry.
What's the problem? Lack of water, disease, drainage?
When the sod was newly installed we watered the lawn about every two days . Then after it was more established we did twice a week for 20 minutes. Now we are at 30 minutes, twice a week.
What could be the problem? Photos of the problem are available at http://www.consejeroviajero.com/lawnproblem
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30 minutes watering won't do anything for your lawn. That won't even give a measurable amount. Put out some containers and water until you have 1/2", and water at least 2 times a week until the grass is well established, then you can cut back to once a week. You'll still need to water long enough to get at least that 1/2" of water down.
Tom J
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,especially on the last photo. St Augustine doesn't like thatch, so always bag the clippings when you cut the grass. Also it doesn't like too much water. You can buy a bag of fungicide at H.D. and a hand spreader.That should clear it up in about 2 weeks. I also only apply weed feed once a year. Too much fertilizer and you can burn your lawn and get those dead spots.
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