mamaung, alan, … no need to marvel…I am in zone 6.
And I lost six or 7 apple trees in March that were outdoors in CONTAINERS.
I lost no trees on other rootstocks whatsoever in that time frame.
We had warm February…and many trees had ‘mouse’ear’ leaves…had broken dormancy in other words.
Those on M111 were lost at high percentage. THEN WE HAD 22 DEGREES and the leaves froze black. And the trees did not resprout even from the rootstock.
G202, G30, Bud9, G41 were fine under identical conditions. (Some of them had not broken dormancy, whereas the M111 had).
Older trees growing in the ground…no problem on M111 or M7 or MM106…just those in containers.