Classic Iron Chlorosis and a common problem with Saint Augustine grass. Most likely problem is high soil PH which you likely cannot fix. Other causes is too much shade, to wet or too dry of soil.

Suggest a soil PH test. Better yet a full soil test. Soil PH maybe fine but has no iron and that is a simple fix. In the meantime spray with a iron product like Bonide. If the problem is shade I cannot help you other than with a chain saw or wrecking ball.

If it is high soil PH you have a life long battle of spraying with iron to force feed feed the grass with iron. Don't worry too much the cinch bugs will be back.

This post was edited by texas-weed on Fri, May 17, 13 at 12:54

Sorry to disagree with you weed. That is fungal disease.

How long did your grass sit on the pallet before you put it down. St Aug is very prone to disease when it does not get good air circulation.

Here is a picture of iron chlorosis in otherwise healthy St Aug...

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Only the grass in the very center of the photo is affected and only barely affected. I happened to catch it right before the entire lawn turned yellow. I have a much better picture of St Aug chlorosis but on a different computer.

Your instinct to spray with a fungicide was correct. I would not have used a spray because I have excellent experience using ordinary corn meal on St Augustine. If the spray does not work, you can still use corn meal but you will have to use a little compost first. Corn meal is a biological solution and your spray has upset the natural biology of the soil. Compost will restore that biology and then you can use corn meal. Yes, this is the corn meal you eat.

As a comment on your previous die-offs: the first one was not due to a major freeze. I don't know what it was, but if St Aug survives almost every winter in Dallas, it is much more likely to survive absolutely EVERY winter in Florida. Second one was chinch bugs...or was it lack of water and mowing too low? Established St Aug must be watered at least monthly to remain alive. It needs to be watered weekly during the heat of summer to thrive. If you have sandy soil yours might need it more frequently. And most St Aug should be mowed at your mower's highest setting. Mow too low and you need to use more water...and you get weeds.