North American Fruit Explorers mailing list at ibiblio

[BekeeprTop@aol.com]

species with best reputation for wet feet toleration:   Malus Fusca of Oregon.

Is there a need/demand for wet-tolerant rootstock?   Yes, apparantly, because some professional researchers have already spent research time looking into Fusca and others.

How develop a particular specimen you're watching?   Actually what you'll have to do to your tree first is screen it - which really is subjecting it to elimination if it fails a series of tests - and your tree to be considered for a rootstock must show an ability to throw roots!   You can't make a rootstock out of a tree that refuses to throw roots, because its not worth yours or a rootstock nurseryman's time to fight with a rootstock that propagates hard.   

Because I can't seem to find anything really effective to do with my life, I've spent some afternoons going up to various apple trees and air-layering them, trying to get them on to their own roots. [Now why exactly I do this is outside the present subject-matter but it probably is a very illogical thing to try to do].   Based on my casual experience, I would say 80% of apples will not throw roots.   That means any given apple you're looking has a 20% chance of having adequate rooting talent to go on to further screenings.   

I'm not sure what your next step is with your tree.   Either you're going to have to learn to root trees yourself, or you're going to have to find someone to come in that does, or you're going to have to send scions to someone who's used to doing it who will graft the scion onto some other apple then root the scion that grows.    There are people in NAFEX who developed rootstocks professionally in universities who could say much more.    
Charlie Paradise, Massachusetts