Rootstock dormancy patterns seem to have little effect on survival of
cultivar, ie, even though ranetka goes dormant ten days later than
antonovka, cultivars on ranetka are able to survive harsher winters.
In short seasons I choose stock that either ripens early or if I want to
take a chance, an cultivar that ripens later, but is hardy enough to endure
cold winters without much preparation. Tests have shown that trees that drop
their fruits even a day or two later than others can suffer more winter
damage. As soon as those last fruits drop, the tree goes full steam into
dormancy. So in a marginally hardy tree late ripening fruits can
significantly effect its survival.