Although it may have been implied by previous replies, one of the biggest
disadvantages to allowing growth from below the graft is that this new
growth will no longer be the same variety as what you had growing above
the graft. Certainly for fruit, this usually means a bad tasting result.
Just remember, a grafted tree is really made up of two different varieties. The
part below the graft is chosen for the resultant size of
tree it will support, vigor of the tree, etc. The top part of tree determines
the variety of fruit or decorative plant that will grow on top
of the base part of tree (rootstock).

Sherwin Dubren

XDeus wrote:

I just purchased 6 crabapples and was wondering if there is a problem
with planting them with the graft underground. A couple of them have
big, ugly rootstock stumps with what looks like a lot of pruned
suckers. Is there a problem with putting that section underground?
They range in length by 2 to 4 inches.