i have seen this phenomena of self seeding plums, older varieties, eg the wild types of small round black plums, eg bullace, damsons, greengage etc, but marjory seedlings and victoria dont seem to be a problem. in the ancient orchards, this is a real problem as after "cleaning and clearing" these small saplings are a veritable death trap, sharp sticks, sticking out of the ground!!. It may be an old trait which is still present in some varieties
as a last resort to damaged trees, try cutting the sapling back to just below the damage. and re graft another scion.
their is dispute about grafting on an existing graft, the ancient texts i have say it actually improves the fruit, but some of the more knowlegdable nursery men(and women) i know, say it doesnt make any difference
ie, a conference graft on a rootstock of quince, PC etc, if you graft another conference scion onto the existing conference grafted scion, it wont make a difference to the fruit. this may not be true of older varieties of apples and pears. i plan to verify this next year with some experimentation with the one year maidens i have(150) so i will let you know how this pans out
consider growing your trees, with the graft as close to the ground as possible and nurture a small branch from below the graft and also from just above the graft. in fact multiple branches on a fruit tree preserve the root bowl and are a better shape for fruit trees. that way if the tree sustains damage, you can quickly graft new scions onto these small stubby branches. unless you plan a commercial orchard, this is a superior way to shape trees. and dont be frightened of vigorous full standard trees. once established you can have live stock in the same field.
scions grafted onto large existing root bowls do a lot better than newly planted saplings
some of the root bowls in newburgh , fife go back at least untill 1500, probably older.
the rootbowl is the most important part of any fruit tree
anyone looking for pear trees
pm me
denmylne
fife