Cider Apple (Malus domestica Borkh.) Cultivars Respond Differently to Summer Mechanical Hedging

Hand-pruning is the second-most expensive annual variable operating cost for orchard production once a cider apple ( Malus domestica Borkh.) orchard is in full production. Reducing pruning labor could increase the profitability of growing cider apples. Summer mechanical hedging was performed for 5 years between 7 and 20 Jul 2019 through 2023 in a cider apple orchard comprising eight cider apple cultivars representing the following four bearing types: tip, Golden Russet and Harrison; spur, Brown Snout and Cap of Liberty; semi-spur, Tom Putt and Campfield; and crab, Puget Spice and Hewes Virginia Crab. All cultivars were grafted on Geneva 935 rootstock and planted during 2014 to 2016, with the central leader of all trees headed in 2017 to equalize tree height and stage of development. Mechanical hedging was conducted at an average speed of 1.63 mph. With 6-ft in-row spacing, 5 seconds, on average, was required to hedge both sides of each tree; therefore, the estimated time to hedge a 1-acre orchard of this density (605 trees·acre −1 ) would be 1.07 hours. Vegetative biomass removal was highest in the first year of this study, but it was not significantly different for all other years. Removal of vegetative biomass was lowest for spur-bearing cultivars (0.18 kg·tree −1 ), and removal for the other three bearing types was similar (0.30 kg·tree −1 on average). Fruit removal during hedging was minimal (20 fruit·tree −1 on average) for all cultivars except for Hewes Virginia Crab (81 fruit·tree −1 ), and there was a positive correlation between the number of fruit removed and yield. Yield for all cultivars showed biennial bearing in the first 3 years of this study (2019–21), and yield was more consistent from year to year during the last 2 years of the study (2022 and 2023). During the last 2 years, the average yield (12.5 kg·tree −1 ) was similar to that during 2019 to 2020 (12.6 kg·tree −1 ), when biennial bearing was greatest. Fruit weight and diameter differed among cultivars, but it was similar to historical data for these cultivars at this location. Summer hedging effects on fruit yield were similar for all eight cider apple cultivars and four bearing types and could be a cost-effective pruning method in cider apple orchards.