I’ve known most of my life the cold truth about the longevity of dwarf trees. Noone really wants to hear it but i feel obligated to say longevity is another reason i prefer standard rootstocks.
Dwarf Fruit Trees vs. Full-Size Fruit Trees | Home Guides | SF Gate
“If you intend to plant a fruit tree that will live many years, then a standard-sized tree may be a better choice than a dwarf tree. Although standard-size trees require more time to reach their full growth, they usually are long-lived. The lifespan of dwarf fruit trees varies considerably, but, in general, they do not live as long as standard-size fruit trees. For example, a standard-sized apple or pear tree is expected to live 35 to 45 years while a dwarf tree of the same type lives only 15 to 20 years.”
Callery such as Bradford are said to live a short period of time 15 - 20 years. Wild callery and most callery today live much longer I would say 35 years would be the minimum but I suspect they will be shocked to see some of them alive at 100 years old+. You may wonder what i base this off of which is trees in my area now well over 50-60 years old that are callery. They planted them like crazy in the 1960s and they are still alive. They said callery would split apart in heavy storms but they don’t do that anymore. They said callery could not survive zone 5 but I have news they are in Wisconsin. They said they could not become forest trees but they did. They said they plan to eradicate them but they won’t. Callery are adapting quickly to any attempt to kill them. They are fantastic rootstock for fruiting pears but do not allow them to reproduce they are doing that already. We don’t want them to become the problem things like elm, cedar, and mulberry have in my area.
Rootstock such as Pyrus betulifolia are not frequently talked about but have similarities to callery. They are great rootstock for Asian and European pears.