Correction:
I had written "Rootstock dormancy patterns seem to have little effect on
survival of
cultivar", I meant to say the "dormancy" of the cultivar with an emphasis on
the word "seem".
The old question of "imparting" of hardiness of rootstock to scion or vice
versa hasn't really been figured out, I don't believe, and that may be
because dormancy and rootstock/scion interactions are complicated. So even
though I don't see outward signs of an effect of the rootstock on the scion,
it may not mean there is no effect.
Kevin B