Use of planting depth and budding height to modify vigour control of Ottawa 3 apple rootstock

The dwarfing apple rootstock Ottawa 3 (0.3) produces trees slightly too large for high density plantings on fertile soils, but it is more cold hardy and better anchored than Malling 9. Our objective was to reduce the vigour of trees on O.3 by budding scions higher or planting the trees more shallowly. Summerland McIntosh was budded at 15 cm onto O.3 and planted such that 6 to 14 cm of the rootstock shank was above ground. Planting depth did not affect tree size, yield or yield efficiency. Increasing budding height from 5 to 25 cm increased vigour control, yield efficiency and the production of root suckers on O.3. Higher budding may be an effective way to reduce the vigour of trees on O.3 in areas where the greater root suckering is not a fireblight hazard.