Journal of the American Pomological Society

In 2014, a multi-year orchard experiment of apple Malus x domestica (Borkh) was established at 13 locations in Canada, Mexico, and the United States using ‘Honeycrisp’ as the scion. Seventeen dwarf and semi-dwarf rootstock genotypes were tested, specifically: Budagovsky.10 (B.10), the Cornell-Geneva rootstocks G.11, G.202, G.214, G.30, G.41, G.890, G.935, G.969, the Malling rootstocks M.7, MM.106, and the Vineland rootstocks V.1, V.5, V.6, and V.7. The industry standard Malling rootstocks M.26 EMLA and M.9-T337 were included for comparison purposes. Tree mortality, trunk cross-sectional area, tree canopy size, amount of rootstock suckering, yield, and fruit number were measured annually. All measured parameters were influenced by location and rootstock, and the interaction of these two factors was significant. Overall, after 10 years and averaged over all locations, rootstock vigor separated into three distinct rootstock classes: those similar to M.9-T337 (G.11), those similar to M.26 EMLA (G.935, G.41, B.10, G.214, G.969), and those more vigorous than M.26 EMLA (V.1, G.30, M.7, V.7, MM.106, V.6, G.890, V.5). G.202 performance was unusual and therefore was omitted from data analysis. Cumulative yields were generally greater on trees with the highest vigor. Averaged over all locations, all Geneva, Vineland, and Budagovsky rootstocks had cumulative yields higher than the industry standards M.9-T337 and M.26 EMLA. The newer rootstocks B.10, V.5, V.6, V.7 and all the Geneva rootstocks, had good to excellent cumulative yields. G.890 stood out as having exceptional cumulative yield among all the rootstock genotypes evaluated. Averaged over all locations, cumulative yield efficiency was greatest for M.9-T337 and all the Geneva rootstocks, as well as B.10. Overall, the strong rootstock by location interaction on cumulative yield observed in this trial illustrates the importance of testing rootstocks at a regional level. These results are reflective of orchard vigor and yields after 10 years and provide apple producers with performance indicators to make more informed decisions concerning rootstock selection for their orchard training systems and planting locations using a weak scion cultivar.