I got a screaming deal on some huge live oaks 15'-20' tall and 8"-12" around in a box of dirt 3'x3'x3'. Planted them with my backhoe about a year ago. Most of them doing very well. Some i murdered by overwatering in this black gumbo clay and our soft water system seems to have hurt a couple. Learned my lesson and had to cut the dead ones down. A couple seem to struggle from the same watering issue but have a nice green bunch of branches with the rest of branches dead. Should I just cut out all the dead branches now when it is going into dormancy? Probably 70% dead branches and 30% green leaves and growing. The ones that took look awesome.

If you ever find any more screaming deals on live oaks that big please hunt me down because I will buy all of em.

Yes. Wait until the first freeze for beetles to die. Paint wounds for oak wilt.

Prune appropriately. Depending on how much is dead, they just may always look like ass.

Where are you located?

Alvin

Yes I bought 27 trees that size for $10,000.

There's a reason you got a "screaming deal" on those trees. That root ball doesn't meet ANSI standards for trees that large - most will be root bound. Probably contributing to some of the dieback you are seeing. If they are root bound, the stress and dieback will continue to get progressively worse as the trees increase in size. You will need to closely monitor those trees, and treat appropriately, for the next 8-10 years.

I've had some luck exposing and cutting the girdling roots on 2 sides of the root ball on some big plantings in Grand Lakes and Cross Creek Ranch in the past 25 years or so-but you risk further stressing the tree.

Try investing into the Industrial Tree Spade Industry, let me know how that works out for you...