I had a plum tree with a fungal disease knows as Black Knot. It was totally leafless last year with branches that would snap like well seasoned kindling. I figured that was it and cut it down.
This spring out of the stump pops a sucker in blossom, trying to act like it might bear fruit.
Most fruit trees one buys are clones grafted onto some other root stock, and in the case of plums the root stock is often cherry. Just have to wait and see.