Comparing Apple Orchard Performance, Fruit Quality, and Summer Hedging Between Bi-Axis and Single-Axis Tall Spindle Training Systems in Western New York

Abstract

Increasing orchard planting density has helped improve grower profits and yields but establishment costs can be high due to a large number of trees. Instead of growing trees with a single leader, two-leader trees could possibly reduce orchard density while maintaining yield and improving fruit quality. To test this hypothesis, an orchard of four cultivars (Gala, Fuji, Honeycrisp, and McIntosh) was established and trained to either Tall Spindle (TS) or Bi-Axis (BA) at 0.9 × 3.6-m spacing. After the third year of growth, all TS trees and half of BA trees were hedged during summer, resulting in three systems to compare from years 4 to 7: 1) TS Hedged (TS Hgd), 2) BA, and 3) BA Hedged (BA Hgd). Measurements of trunk cross-sectional area (TCSA), yield, fruit quality, and biennial bearing index were recorded for 7 years. At the end of the study, total TCSA was larger on BA trees compared with TS Hgd trees across cultivars. The BA and BA Hgd trees had higher cumulative yields compared with TS Hgd trees across cultivars. Fruit size was reduced on BA and BA Hgd trees compared with TS Hgd trees, but all three systems had similar fruit color, firmness, and soluble solids on average. The biennial bearing index was lower with ‘Gala’ and ‘Fuji’ compared with ‘Honeycrisp’ and ‘McIntosh’ and was lower on BA and BA Hgd trees than TS Hgd trees. After 7 years, there was no obvious benefit of using hedging to improve fruit quality, but higher yield from BA trees over TS trees when planted at the same density for ‘Fuji’ and ‘McIntosh’, regardless of hedging during the summer, was achieved. It is possible that some cultivars benefit from the BA system and could be planted at 15% lower planting density than TS trees to achieve the same yield.