Interesting article by Eliza Greenman, a creative experimenter in ways to grow low input Southern heirloom apple varieties by using standards and own roots. In this article she describes her Virginia experiment using native crab as a temporary nurse rootstock until the heirloom scions root on their own.
Root Grafting Southern Heirloom Apple Varieties on (nurse) Native Crab Rootstocks
The girdling aspect to transition from grafted roots to own roots is really interesting.
I think I have read that long ago some folks would take apples grafted to some seedling rootstock and bury the graft so the tree eventually grows on its own roots. Not sure if there is some advantage to “own root” trees??? Eliza is very creative, constantly experimenting.
Longevity seems to be the primary driver towards wanting a full size standard own roots tree.