Live oak - herbicide damage?

[Michael55]

I have a live oak, approx. 12" diameter, that has started to
drop it's leaves in the past few days. I has been hot (in
the 90s). The leaves looked scorched and some are curling
(and some are not curling...just looked burned).
Approx. 3 weeks ago I applied a herbicide to my lawn (2-4-d,
dicamba). In hindsight I believe I sprayed in the dripline.
However I have another live oak about 30 feet away that
doesn't appear to have any damage (no leaves dropping).
My neighbor also applied some about 1 week ago.
I also fertilized last week (15-5-10). If the roots got
damaged, how long does it take to show? 1 week, 2 , 3???
I know this is alot of data, but the tree is really dropping leaves
like crazy. I fear it will be leaf-less in another day or two.

Question: if it is herbicide damage, what can I do? I started
watering heavily last night, in hopes of diluting anything in the
soil and providing some water to the tree (it will be 90s for the
next two days).
Do live oaks usually pull through this type of damage? I know
this is a relative question (dependent on the extent of damage).

I have pictures of the leaves, if someone would care to comment
on them.

Any comments would be appreciated.

Thanks, Mike in Texas

[Acer]

Dicamba can give similar symptoms. You often see curved petioles, distorted leaves, with dieback or defoliation in evidence as well. If you applied the herbicide in hot still weather, some herbicides can evaporate and affect foliage which overhangs the treated area. I'd imagine it's too late to do anything about the damage. If the tree was healthy before, with a good reserve of stored carbohydrates, it may survive..you may find the tree puts on a new flush of growth, replacing lost foliage.

[Michael55]

Hi Acer,
Thanks for the reply. In addition to posting here, I took a
sample of the leaves to the local University agriculture
research center and they analyzed it. Looks like herbicide
damage along with some Oak Leaf Blister (fungus - Taphrina caerulescens).
As far as I know, the tree was very healthy prior to the
"accident" with the herbicide. I had fertilized a couple of
months ago, and also just a few days before the leaves
started to drop.
Basically I'm in the waiting stage now (waiting to see if
the tree survives).

Cheers, Mike