Mount Royal plum
Mount Royal is a very cold hardy plum tree that is a classic prune plum (although great for fresh eating as well). The tree makes gorgeous flowers in spring, and the fruit’s skin is a beautiful deep purple, with amber/golden flesh when ripe. The plums are freestone (the flesh separates easily from the pit).
Mount Royal often sets a heavy annual crop, and thinning the fruit will help individual fruits size up.
Disease resistance:
In my experience, Mount Royal has not had much of a problem with black knot, the most common disease of plums. I may have to remove a small branch or two every other year at most. I haven’t experienced much of a problem with brown rot of the ripe fruit either.
Pollination:
At least partially self-fertile. I find that my own Mount Royal tree, as the lone European plum in my backyard, fruits well with out another plum nearby. As with all trees that are self-fertile, they are said to fruit better with a compatible pollination partner nearby.
Parentage:
Said to be a chance seedling discovered near Montreal, hence its name.
References:
Plums for Cold Areas of Eastern Canada.