I suspect some bark beetles but I'm only guessing without seeing it. Could you bring in a sample from the tree just starting to show symptoms? If you can reach, take branch that still has both dead and live tissue on it and bring it into the Pulaski Co Extension office. We are open 8 to 4:30 M-F.
Also, do you see sawdust around the base of the tree or on some of the branches?
We'll try to get this solved.