Effects of Rootstock on Productivity and Pruning Requirements of ‘Starkspur Supreme Delicious’ Apple Trees in the NC-140 Cooperative Planting

Abstract

Estimated early yields per ha. (1982-1985) of ‘Starkspur Supreme Delicious’ apple trees planted on nine rootstock clones in 1980 were directly related to estimated planting-system density except for trees on M.27 EMLA. In contrast, estimated yields per ha. from 1986 through 1989 for all rootstocks were not influenced by estimated planting-system density. Dormant-pruning time requirements from 1982 through 1989 were most influenced by the need for a ladder during pruning. Where ladder use was unnecessary, dormant-pruning time was inversely proportional to tree size, but to a much lesser extent than for trees requiring a ladder. Pruning costs represented a small fraction of estimated crop value. Although cumulative estimated production per ha. did not differ significantly among rootstocks, there was a significant, positive relationship between estimated net crop value (crop value minus pruning costs) and estimated planting density.