Is it peeling off down to the cambium? Is it on the southwest side of the tree? If so it's probably southwest injury caused by alternating freezes and heating in the sun.

OK this is the old tree where the bark came off last year. I cut off about 2/3 of it, quite dead.

Another shot of the old tree, more bark peeling.

The young tree, facing north. This damage is all below the graft union.

The east side of the young tree, with a piece of the peeled-off bark.

Here is where I scratched the surface to see if there was live tissue beneath it. It looked green at first but turned red in less than a minute. I have no idea whatsoever if this means anything.

The old tree is dead or headed in that direction. But the young tree just looks to be peeling the oldest, outer bark. That doesn't look serious to me.

tree of apple , it have at least 50 years old , i think u can not srvive it ,

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I have two espalier apple trees that look exactly like that. I thought it was collar rot or some other disease. It looks very serious to me but, I hope you are right and this is normal.

Hope you're right FN.

The older tree is certainly dying - all but 2 scaffolds died last year. But when I saw the tree next to it peeling bark so copiously, so much like the dying branches on the other tree, I began to worry.