Probably black knot:
http://www.nysaes.cornell.edu/pp/ext.../blknstf.shtml

It's nasty stuff. I battled it for several years on my two Stanley prune
plums, by carefully pruning out the affected branches, but it spread rather
dramatically. I was not willing to use fungicide sprays, and between the
black knot, and the brown rot on the plums, and the plum curculios, I
decided to take down the trees and grow something more satisfying.
Hopefully you will have more success than I.

Sue

Zone 6, Southcentral PA


"vincent p. norris" wrote in message
...
Ugly growths have appeared on some branches of my plum tree. They
gird the branch and are a couple of inches long.

Can anyone identify them and tell me how to stop them?

Thanks. vince norris