As pictured, this Quercus virginiana has a number of dead limbs. There is really no external evidence to give hints as to what is going on. The browning goes back all the way to the trunk. As you can see from the picture, there is no where on the tree where the browning or yellowing is starting elsewhere, so you can't tell what the intial discoloration looks like before it goes completely brown. On the brown limbs there is no green foliage. I inspected the trunk and all I can see are sapsucker holes. There are some holes that aren't as patterned so might could be borers too but it is hard to tell since the sapsucker has visited. This area is irrigated, but it hasn't been running on a regular basis. The other plants in this bed, loblolly pine, crape myrtle and dwarf yaupons look fine. We have had a good period without rain and temps into the upper 90's. Could this be drought stress? But doesn't drought stress usually show symptoms from the top down? Any thoughts would be appreciated.