Rootstock Effects on Growth and Fruiting of a Spur-Type and a Standard Strain of Delicious Over Eighteen Years

Abstract

Red Prince, a standard strain and Redchief (Campbell strain), a spur-type strain of Delicious apple were grown on several rootstock/interstock combinations for 18 years. The dwarfs were Malling 9 (M.9), M.26, M.9/Malling Merton 106 (MM.106), and M.9/M M.111. The semi-dwarfs were M.7, MM.106, and MM.111. Five three-tree replications were used. In-row spacing was varied from 1.8 to 5.5 m depending on the scion/interstock/rootstock combination; between-row spacing was 6.1 m throughout the experiment. Tree survival ranged from a high of 100% for five combinations to as low as 13% for both Delicious strains on MM.106. In the dwarf group, trees of both strains on M.26 were the largest, those on M.9/MM.111 were intermediate, and those on M.9 and M.9/MM.106 were the smallest. The greatest numbers of rootsuckers were on trees on M.9/MM.111 and M.7. Crop density tended to be higher with Redchief than Red Prince and higher in the dwarf than semi-dwarf group. With both Redchief’ and Red Prince, cumulative per-tree yields were greater on M.26 than on M.9 or M.9/MM.111. Trees of Redchief on the three semi-dwarf rootstocks yielded similarly; Red Prince trees on MM.111 out-yielded trees on M.7. With both strains, trees on M.9 and M.9/MM106 tended to have higher cumulative yield efficiencies than those on M.26 or M.9/MM.111. Cumulative yields (T/ha) for both strains were highest for trees on M.26 compared to all other rootstocks. Cumulative yields for the three semi-dwarf rootstocks differed little with either scion.