Hi there:
I have a no ID dendrobium nobile
that I re-potted last year. Since then, it has produced three new growths, and flowered twice (!!).
It is preparing to flower again on two of the three new growths.
Old growth wrinkled up, and according to research here, this is normal. However, the eldest stalks are now beginning to turn black, as in the picture. They are slightly squishy. I would prefer to leave them alone, but checking in just to make sure I shouldn't take any action.
Thank you for your time!