Oaks are the classic coppice tree, so you can and should hack away at it. Cleaning out the competition should give it a new lease on life. If any branches are noticeably colonized by fungi, you can remove those as the tree will do it on its own anyway.
There is really no point in giving it any fertilizer. A tree that old is going to have an immense mycorrhizal network established underground, and it can get the nutrients it needs without any help from you. Just make sure that there is plenty of leaf litter and biomass on the ground to be resupplying those nutrients.
Timothy Hewitt-Coleman
Posts: 177
Location: Port Elizabeth, South Africa (34 degrees south)
They are only eating the heart of the tree that is already dead wood.
If you want you can get some rock dust and apply it to the drip line of the tree.
In nature things die, so if that is the case do not be afraid to plant something it it's place.
There are plenty of nut and fruit trees that will grow in your location
Iterations are fine, we don't have to be perfect
My 2nd Location:Florida HardinessZone:10 AHS:10 GDD:8500 Rainfall:2in/mth winter, 8in/mth summer, Soil:Sand pH8 Flat
Timothy Hewitt-Coleman
Posts: 177
Location: Port Elizabeth, South Africa (34 degrees south)