Question
I live in the Dallas Ft. Worth metro area and have a bremuda lawn. I have developed large dead grass areas and have not been able to correct this situation even with fertilization daily watering and grub worm treatment. Is there a fungus , or infestation pboblem that i can test for and treat ?
Any advice would certainly be appreciated.  

Answer
It could be a number of reasons such as excessive thatch, chinch bugs, Pythium, or brown spot diseases. It is not easy to trouble shoot based on a description of "large areas dead grass" (sorry I know it is difficult to describe but I can not tell. It would be different if I was there to look at the grass).

I have an article with some descriptions (about zoysia but it applies equally to bermuda grass lawns):

This may help you diagnose.

http://www.walterreeves.com/lawns/article.phtml?cat=6&id=559

Brown patch is a fungal disease that begins in a small area and spreads in a circular pattern (getting larger). Brown patch can also be distinguished from other lawn problems by the presence of dark, smoky rings on the edge of this ever-enlarging ring. There will also be green sprigs of grass within the affected circle.

Another lawn disease which resembles brown patch is summer patch disease or "take all disease" (you can try to guess why it is named so). As opposed to the "smokey ring" this disease create a circular area with the edge of the circle having browning or yellowing grass and the interior of the circle having a more healthy green appearance, this patch disease symptom has brown, dead grass throughout the circle.

You can also scout for chinch bugs by twisting a coffee can (with bottom removed) 1" into the soil between the green and dead grass and fill with water to which 1 tbsp of dish detergent is added. If there is chinch bugs they should float the the surface.