diease cherry tree

Yet another of the cherry tree.
Let's hope these photos enable GoY members to advise you.

That looks like canker - nasty. Are leaves dying back? if so they do not drop but remain dead on branches. Difficult to treat affected areas must be cut out and cuts sealed with tree paint. removed branches should be burnt to prevent cross infection.

Whole tree should then be sprayed with Bordeaux mixture.

Oh that's too bad. I hope it can be saved.