Hmmm, seems nobody knows.

FWIW, I planted 5 trees (Bruce, Methley, and Santa Rosa) 4 years ago. All died, except one Bruce. Last year I made 2 plums. Last year I planted a Hog (or Flatwoods) plum. We'll have to see if that one does any better. I live in Houma.

To me, the best plums are actually the small wild ones, that are grrn when immature and yellow when matured. Anyone knows where to get these trees?

You mean Japanese Plum Trees?
I've got a few, matter of fact, been pulling out small seedlings , throwing them in the next field, found few of them dried in the lining of the wren nest, love those little birds, great singers, for one.
Japanese plums are found in the woods around here-squirrels spread the seeds.
I live in Belle Chasse.