Pruning time × cultivar effects on flower-bud hardiness in northern highbush and southern highbush blueberry

Authors: Ehlenfeldt, Mark; Vinyard, Bryan

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/2015
Publication Date: 5/28/2015
Publication URL: http://handle.nal.usda.gov/10113/61505
Citation: Ehlenfeldt, M.K., Vinyard, B.T. 2015. Pruning time × cultivar effects on flower-bud hardiness in northern highbush and southern highbush blueberry. HortScience. 50(5): 673-675.

Interpretive Summary: New blueberry varieties developed for northern growing areas in the U.S. are typically hybrids between northern-adapted and southern-adapted breeding material. Currently, commercial growers in New Jersey may begin pruning as early as late September, often before plants have gone fully dormant, thus raising concerns about winter hardiness for these new cultivars. A study was conducted to determine if early-fall pruning of either northern highbush or southern highbush blueberries was detrimental to the development of winter cold-hardiness. Flower bud damage was assessed. Two years of bud damage evaluation demonstrated that early fall pruning had no negative effect on northern or southern highbush blueberry cold hardiness. This information is important to growers and researchers for developing best management practices for new cultivars.

Technical Abstract: A study was conducted to determine if early-fall pruning of either northern highbush or southern highbush blueberries was detrimental to the development of optimum and levels of mid-winter cold-hardiness. Using a detached-shoot freeze-thaw assay, flower bud LT50 values were determined in early January for both ‘Jersey’ and ‘Legacy’ blueberry bushes that had been subjected to early and late pruning protocols. Across two years, intrinsic differences due to genotype were present, but no significant differences due to pruning time were observed.