mastino,
I had a couple of beach plum seedlings from OIKOS Tree Crops. One was quite productive, though there wasn't much pulp surrounding the pit - then the neighbors reworked their septic leach field, and it resulted in that one 'drowning'. The other one blooms profusely, but without a pollenizer, it hasn't set any fruit.
One thing I noticed, though, in the 10-12 years they'd been in the ground here, I've never seen any black knot on them - or brown rot on the fruit, either, for that matter.

Thanks lucky p, great info & I luv the site OIKOS Tree Crops, Ill be ordering! One last thing how was the taste of the plums? THANKS!