PERFORMANCE OF 3 APPLE CULTIVARS WITH 22 DWARFING ROOTSTOCKS DURING 8 SEASONS IN OHIO

Rootstocks in this trial produced a continuum in tree size that could logically be grouped with the Malling standards as follows: M.27 size group = B.146, P.16, P.22, Mark and MAC.9; M.9 size group = B.9, V.1, V.3, P.2, M.9EMLA, CG.10, MAC.39 and C6; M.26 size group = V2; M.7 size group P.1, V.4, V.7, OAR1. The virus-free selections M.9MLA and Mark did not differ significantly in size or cropping from the original selection of M.9 and MAC.9, respectively. In general, as tree size increased, trunk cross-sectional area (TCA) growth increment was greater as the trees aged. The following root-high stocks had relatively high biennality indexes on both 'Macspur McIntosh' and 'Redchief Delicious' the most biennial cultivars in this trial: CG.10, M.9, MAC.39, V.2, V.4, V.7 M.7EMLA. 'Macspur McIntosh' on OAR1 was characterized by having long shoots and large numbers of non-flowering spurs, while 'Macspur McIntosh' on Mark, M.27EMLA and MAC.S tended to have short shoots and the fewest non-flowering spurs and vegetative shoots. The following root-stocks tended to increase the density of flowering spurs on 'Macspur McIntosh': M.9, M.26-EMLA, V.4, M.7EMLA and V.1. 'Lawspur Rome Beauty' was the most productive and efficient with the lowest bienniality index and was intermediate in tree size and TCA change compared to 'Macspur McIntosh' and 'Redchief Delicious.'