tell me what you know about interstem apples.
....graft length, depth of planting and what if any influence the former have?
A few years ago I had a very brief exchange with Jim Cummings about interstem apples. His strong recommendation was for half the interstem to be below soil level.
I was not clear on the nuances of the choice, how it would effect the growth of the tree to have some of the dwarfing stock rooting (MM111/G11).
I have since read some slight references to length of interstem having influence as well.
I have a few this year and will plant them as per Dr Cummings recs, but I would like to understand the reasoning better.