posted 7 years ago
Hello!
In my opinion as a professional Arborist. I wouldn't prune more then 25-30% per year in restoration. I would do 15% maximum in height reduction, and 15% maximum in cantilever weight reduction on outer limbs per year. Those are your 2 major factors for restoration beside the 3 Ds and your crossers. Start with the most sever, and work your way to the less needy parts of the tree. Deadwood doesn't count tward the %, but before you do any live wood, you better do damaged, diseased, and crossing branches, because they do count against the total 30%. The full restoration will take at least 3 years, but you'll have a nice tree that will most likely produce biannually, without to much yearly pruning or at least proper friut thinning annually. Personally unless you like climbing and working on big apple trees every year. I would take some live wood from it for scion grafts, and gradft it to a nice disease resistant dwarf or semidwarf root stock. Once your new grafts are good to go, you can without concern, cut down that tree. Those old trees are often vectors for disease, and aren't usually very disease resistant compared to many newer varieties breed to combine the disease resistance of the older hardy varieties. Then you have preserved the tree for potential genetic diversity, if its rare. You can use it as a manageable pollinator, if the flower cycles are congruent with your new trees, and can do the grafts yourself if you're up to it. You'll know all those factors before the grafts are done, and can give them or trade them away, if they are of no use to you.
Something to think about.