Comparison of standard pruning with cordon pruning on blackberry yield and quality

Abstract

Blackberries (Rubus spp.) are an economically important specialty fruit crop cultivated in temperate and subtropical regions worldwide. Advances in cultivar development, trellis systems, and postharvest handling have contributed to rising global production and growing market demand. Among cultural management practices, pruning and trellising play critical roles in shaping canopy architecture and, in turn, influencing fruit quality and yield potential in commercial blackberry production systems. This study evaluated the effects of two pruning strategies, standard pruning, and cordon pruning, on fruit yield and fruit quality in floricane-bearing 'Ouachita' blackberry plants trained on a modified V-trellis system. A randomized complete block design with four replications was implemented over two growing seasons (2023–2024). Mixed model analyses were conducted for six response variables, U.S. No.1 (Grade 1) berries, U.S. No.1 (Grade 2) berries, white drupelet disorder, non-marketable fruit, °Brix, and harvest time, to assess the effects of pruning system (cordon vs. standard), year, and their interaction. Pruning system significantly affected Grade 2 berry yield (F = 8.3, p = 0.01), with cordon pruning producing more Grade 2 berries (LSM = 1,247.0 g) than standard pruning (LSM = 964.6 g), a difference of 282.4 g (SE = 97.9). A significant year × pruning interaction was also detected for Grade 2 berry yield (p = 0.01), indicating that the magnitude of this effect varied between growing seasons. Grade 1 berry yield had no statistical differences between treatments (p = 0.2). White drupelet disorder and non-marketable fruit showed non-significant trends associated with pruning system (p = 0.07 and p = 0.5, respectively), with cordon pruning numerically associated with fewer non-marketable fruit. °Brix and harvest time, evaluated only in the second growing season, were not significantly affected by pruning system (p = 0.2 and p = 0.5, respectively). Overall, the results revealed no significant difference in performance between the cordon and standard pruning treatments. Environmental variability between growing seasons, particularly rainfall during harvest, appears to have influenced treatment effects across several response variables, contributing to periods of overripe fruit when rain prevented timely harvest. Cane dieback was also observed during the study and may have further confounded yield outcomes for both pruning systems. Additionally, fruit production slowed earlier in the season under standard pruning compared to cordon pruning, suggesting a difference in cropping duration between the two training methods. These findings offer useful insight into the tradeoffs growers may face when selecting a pruning and canopy management strategy for blackberry production in the Mid-Atlantic region.