Centipede Grass Problem
Please help me identify my grass problem! This lawn was installed in '07 and not watered well. We moved in Oct '08 and the yard looked pretty bad. We watered 1" per week over the growing seasons and the grass seemed to do pretty well. Fast forward to this year...We have had severe drought (NO rain) to the point of watering every other day 30 min (we also have very porous/sandy soil) instead of once or twice per week like usual. We fertilized with weednfeed in July and the grass is mowed every 7-10 days to a height of 3". Now there are dead spots with light green grass around them. I thought maybe I was overwatering, but the rest of the grass looked GREAT. I am thinking grubs but am a professed grass idiot. What do you think? Thank you in advance for any advice! I included 2 photos of my healthy areas so you can see what I mean by my definition of healthy.
Here is a link that might be useful: Pics of lawn