Apple tree bark peeling off
Last year, I found an oldish apple tree dying because much of the bark was peeling off and rotted.
Today, I saw that a relatively young tree's bark is peeling off the rootstock. Not rotting at all, thin bark just peeling off the wood. The tree looks quite healthy so far, but I doubt if it can survive what seems to be the equivalent of girdling.
The two trees are next to each other. Is this a disease? Should I be concerned for the even younger trees? Are there bark-saving measures I can take?