Foliage dropping on my Post Oaks

[Fatcord]

this is the only pic it is allowing me to load. when my wife gets home she can figure it out. I also have pics of the entire tree

 

[pcarborist]

FC, I think what you are seeing is the effects of drought. It's a survival mechanism by the tree to shut down the xylem when there's insufficient water and because only the outer three rings conduct water it doesn't take much to cause dysfunction. It's like your body shutting off the blood flow to your feet when you get hypothermia.

 

[Fatcord]

Sure Thats what I wood think but given the facts.
#1 the only trees with foliage loss are the trees that were fert last fall.
#2 the foliage is breaking off at the abcision zone.
#3 the trees outside of this area are showing no signs of stress.