Post Oak leaves falling off

[LWheeler]

Have post oaks in SW Arlington. In the past two years have had two trees that had to be taken down due to dying. Now another tree is dropping clusters of leaves. Some are dead, some are still green. The branch that the cluster is on seems to be cut straight. I ahve taken this to a close nursery supply and the thought that this might be caused by someone spraying herbicide. These clusters are coming from all over the tree, not just the outside edges.

Also, on the two trees that have died, on branch started turing brown on the outside of the tree. Then the dying would move towards the trunk of the tree. Once this branch had died back to the trunk of the tree, the tree died.

Does anyone have any ideas as to what is happening?

[Leslie Finical Halleck]

Well, Post Oaks in general are very intolerant of just about any human activity. Excess water from sprinkler systems; soil compaction from foot traffic, parking cars, driveways; Any digging or construction around their roots, etc. Activity like this can kill a post oak very quickly. Herbicide spraying can also be the culprit. If herbicides have been sprayed in the yard around the tree, that could very well be the problem.

[The Ent]

Basically if you do anything under or around a Post oak tree, besides maybe the occasional nap in the shade or a picnic, it'll affect that tree. They absolutely do not tolerate the changing of any environmental variables whether it be irrigation, soil changes (including adding amendments), grade changes, etc. At best it'll stress them but they could live if you quit whatever it was that caused it (unless it's a grade change- even undoing that might not help) and at worst it'll kill the tree.

This is why you see them growing wild but seldom on a residential lot.

[wnorris]

I am not a tree expert, but I have 5 acres around my house with primarily post oaks and cedar elms. I have also had a similar problem to you on a few trees, primarily where I have made changes (grass, flatwork, etc). My experience is, if the tree is dropping the leaves, that is a good sign -- I was told that it means stress, not death. When this has happened, I applied the sick tree treatment and the trees came back the next year -- strong. Where I have had more problems is when the leaves turn brown and don't drop -- I havn't been able to revive those yet... soon after, the bark starts coming off.