I am in Central Florida. Over the last month my four year-old azelea's leaves have been turning brown and NOT falling off. About 1/3 of the leaves on this up-until-now healthy plant are now brown. I assume that it is dying. I don't know why or if there is anything I can do.

To add to my frustration, two Butterfly bushes and two young maple trees are doing the same thing. None of these are next to each other and there are healthy trees an shrubs in between them.

Any suggestions on what I might be able to do?