Help with dying trees...!

[KatyMan]

We live in Katy, TX, far west Houston and have several Japanese blueberry trees and one Japanese plum that are dying and we don't know why. The earliest we can get somebody here to take a look is next week, so I thought I'd post here to get some opinions. Here are the pics:







Now it's been pretty hot here lately, and we've had probably an average amount of rain, and the sprinklers run a couple of times a week, so they should be nicely watered. Does anyone have any idea what could be wrong?
I don't know why the pics show up sideways, they don't on direct link...

Thanks, and I'll hang up and listen