I have a bunch of MDC american plums set in 2012 as seedlings. We tubed them all and they did well. By year four a few were fruiting, and by year 5 some were heavily.
View attachment 41599
My Kentucky soil is heavy clay and quite wet where these are planted. I haven't checked ph lately. They don't seem to anchor really well as a couple of the larger ones tipped over in wind storms ~years 7 & 9. But they are part of a plot screen so I didn't try to prop them back up and they have continued to fruit and sucker. I've left them in tubes and haven't knocked down competition right around them so they didn't sucker much for a number of years but are now. Fruit varies in color, is small (nickel sized or a bit bigger) with a big pit, not really tasty to me, but the critters keep them vacuumed up while they are dropping in August/September.
View attachment 41600
View attachment 41601
We have some native plums that show up along edges, creek bottoms, etc. They have a bit larger fruit, less brightly colored, but better taste; they don't produce nearly so many plums as the MDC stuff though. I've not noticed major deer browse on them.