I have been told that the height of the graft on the rootstock affects the size of the mature tree, i.e., the higher the graft the smaller the resulting tree will be. For space reasons I need to keep my trees in containers, and therefore most of the apples are on M9, or P22, but I would like the improved resistance to disease that I would have with M26. If the information regarding the effect of graft height on size is true, how high up a M26 rootstock should I graft to achieve a mature tree intermediate in size between M26 and M9? Also, all the trees are currently in the largest size of duraco pot. Do I need to anticipate the M26 ones outgrowing their pots?