I’m thinking to plant a new apple tree on which I would graft other varieties. If I plant a diseases resistant variety, does the resistance apply on the branches I’ll graft on the tree?/ should I plant a very resistant variety to graft on?
I like the idea of using a disease resistant tree and do various grafts on the limbs. Not sure but you might save your core tree if the limbs are hit hard by fireblight.
That’s a very good idea. But in general any resistance of the mother tree won’t be transferred to the scions grafted onto it. As mentioned it could save the tree from FB but the scions won’t be more resistant.
The same applies to diseases of the leaves or fruit. Nutrient disorders could be more complicated.