Fruit tree rootstocks: M9, M26, M111, EMLA
The rootstock label on a fruit tree is more important than the variety name for predicting long-term performance. It determines tree size, precocity (how soon the tree fruits), soil tolerance, anchorage, disease susceptibility, and infrastructure requirements. Most gardeners pay attention to the.
The rootstock label on a fruit tree is more important than the variety name for predicting long-term performance. It determines tree size, precocity (how soon the tree fruits), soil tolerance, anchorage, disease susceptibility, and infrastructure requirements. Most gardeners pay attention to the variety name ('Honeycrisp', 'Bartlett') and ignore the rootstock designation — this is backwards for practical orchard management.
This guide covers the naming systems, major rootstocks for apples, pears, and stone fruits, and how to match rootstock to site conditions. Sourced from Cornell, Penn State, and UMass Extension.
Understanding the naming systems
Per Cornell Cooperative Extension:
Malling (M.) series: Developed at East Malling Research Station, Kent, England, early 20th century. Designated M.2 through M.27 (non-sequential; some numbers discontinued). The most widely referenced dwarfing apple rootstocks globally.
EMLA: Stands for East Malling/Long Ashton. Denotes a virus-tested, virus-free clone of an existing Malling rootstock. "M.9 EMLA" is a virus-free clone of M.9. Per Cornell, EMLA designation assures freedom from latent viruses that can reduce tree performance even without visible symptoms.
Malling-Merton (MM.) series: Developed jointly by East Malling and John Innes Institute (Merton, now Long Ashton). Includes MM.106 (semi-dwarfing), MM.111 (semi-standard), and others. MM. rootstocks are more vigorous than M. dwarfing rootstocks and provide better anchorage.
Geneva (G.) series: Developed at Cornell University, Geneva, NY, from crosses of Malling rootstocks with disease-resistant species. Designated G.11, G.16, G.30, G.41, G.65, G.935, etc. Per Cornell, Geneva rootstocks offer similar or superior dwarfing to equivalent Malling types with improved fire blight and Phytophthora root rot resistance.