The most common semidwarf rootstocks used for apples are M.26, M.7 or M.7a, MM.106 and MM.111. 106 will produce the earliest bearing trees. The MM.106 and MM.111 will produce the largest of the semidwarf trees. Dwarf fruit trees often require fewer pesticides. Since the trees are smaller than standard-sized trees, air circulates better inside them and they dry off more quickly.
Most diseases develop under wet conditions.
Small trees that dry off quickly have a reduced potential for disease development and therefore require fewer pesticide applications to control disease. In addition, when pesticides are necessary, it is much easier to obtain a uniform application on small trees. Uniform pesticide deposits are necessary for disease and insect control. The interstem tree is another category of rootstock that might be available. It has a small stem section of M. 9 grafted between an understock such as MM.111 or MM.106 and the variety.