Congratulations on the plum, it will be Rakia 😆
Did you also let the apple tree with its branches spread out to form a fence?
Because some apple trees like to be pruned more like a column. In fact, that is their breeding form. Of course, it also depends on the apple tree variety. But I know that they like to bloom and bear fruit on older, perennial trees (preferably three years old) and on a kind of "cakes".