Performance of dwarfing apple rootstocks in five trials in British Columbia, Canada

Five trials of dwarf and semi-dwarf apple rootstocks were conducted, with the objective of identifying hardy, yield-efficient rootstocks adapted to the regional climate, and suitable for the newer tree training methods used in high-density plantings. The rootstocks tested were: Jerk 9 (J.9), Mark, Ottawa 3 (O.3), Budagovsky 9 (B.9), the Polish rootstocks P.2, P.16 and P.22, and the Malling rootstocks M.4, M.9 EMLA, M.26 EMLA and M.27 EMLA. The scion varied among trials and included 'Macspur McIntosh,' 'Summerland McIntosh,' 'Jonagold' and 'Shamrock.' Mark, J.9 and P.16 produced trees similar to M.9 EMLA in size and productivity. P.16 was slightly more yield-efficient than M.9 EMLA, and average fruit weight on Mark was slightly lower than on M.9 EMLA or J.9. Mark and J.9 were more precocious than M.9 EMLA, as judged by early blossom production. Trees of this size would be most suitable for high density plantings on most sites in British Columbia. O.3, B.9 and P.2 produced trees larger than M.9 EMLA and similar to M.26 EMLA in size. P.2 was lower in yield and yield efficiency than trees of similar size on 0.3 and B.9. O3 and B.9 were similar in all respects, except that 0.3 was more yield-efficient in one trial. M.26 EMLA was slightly more precocious than O.3. 0.3; B.9 and M.26 EMLA would be useful on cold sites or where site or scion vigor is too low for M.9. P.22 and M.27 EMLA produced trees that are probably too small for conventional slender spindle and vertical axe training. Vertical axe trees were more precocious than supported central-leader trained trees, but not slender spindles.