I do have this ones in a while on my trees and it seems in the long run...over several years, at this spot, the bark dies completely all the way around and the whole limb or when on the stem everything dies above.

I'm now, [another young tree] trying to remedy by cutting the effected area off clean and seal with Dr. Farwell's.

Please voice your opinion whats causing this.

Bacterial canker is one culprit...and pruning out seems the thing to do, but here it's on the stem and I'd loose most of the tree.