Stark bros has 20% early order discount, so I called to ask about rootstock used. For apples, dwarf M9 or M26 semi dwarf M7 or Bud118. The semi dwarf still has me scratching my head. There is quite a bit of difference in M7 vs B118. You can not request one or the other, in fact they will not know which one you get. It will just be semi-dwarf. I was told commercial orders are filled with particular rootstock after that trees are dug and thown into a communal bin, so what you get you get. It does seem like it would be that tough to segregate trees by rootstock, but the majority of their customers must not care.