Pruning overgrown old apple tree
Have a beautiful healthy apple tree at a farm on the Alsea river, perhaps 25 years old...maybe more. It has four varieties by grafting and yields very well. It has been unattended for maybe 5 years. The upward shoots are huge and the tree is getting too tall. I cut all the suckers around the trunk and trimmed back low hanging branches. The rest of the tree has not been touched. Question: How much can one cut back per year without shocking the tree into zero yield? My dad once cut a King apple tree way back after years of neglect. It had great apples until he trimmed it...it never recovered. I don't want to hurt the tree.
Here's a good source of information. Pruning guide for old apple trees from OSU Extension. https://catalog.extension.oregonstate.edu/ec1005/html
Also, here's a link to the Pacific Northwest publication "Training and Pruning Your Home Orchard" which will provide some excellent guidance. https://catalog.extension.oregonstate.edu/pnw400/html