New “Fruiting Wall” Canopy Architectures and Training Systems for Sweet Cherries

Highly-structured canopy training systems for sweet cherries are not new (e.g., Marchand Drapeau, Tatura trellis), but previously these have not been adopted widely.  During the past decade, the commercial availability of precocious hybrid rootstocks that also confer varying levels of tree size control have stimulated the development of several unique training systems having the objective of establishing a highly-structured, continuous narrow vertical canopy or “fruiting wall”. The first precocious fruiting wall research in North America (G. Lang) used radical orientation of tree leaders and selective bud removal to create trellised, bi-lateral cordon canopies similar to the lyre system for grapevines. This has evolved into the unilateral “Upright Fruiting Offshoots” (UFO) high density system (M. Whiting) that provides uniform, renewable fruiting units  (comprised of spur and non-spur fruiting sites) that simplify canopy and crop load management, and increase the potential for some orchard mechanization and improved labor efficiencies.  Recent research at MSU on UFO tree spacing, trunk angles, and upright shoot formation strategies will be discussed.  A second fruiting wall strategy is evolving in Italy, the super slender axe (SSA) or uni-baum ultra high density planting system (S. Musacchi).  Rather than creating renewable mixed (spur and non-spur) fruiting units, this system promotes the exclusive renewal of non-spur fruiting sites via “short pruning”, an annual renewal of all shoots by retaining only basal non-spur flower buds plus 1 to 3 vegetative buds.  Recent research at MSU testing the SSA system also will be discussed.  A third fruiting wall system originating in France (G. Charlot) is focused less on uniform shoot renewal than on mechanical hedging prior to harvest. Although not under test at MSU, this system also will be discussed with regard to canopy fruit-leaf physiological relationships compared to the other two systems.  Furthermore, scientists from the NC140 regional research project recently established coordinated sweet cherry trials across North America to broadly examine 3 promising high density training systems, including two fruiting wall canopies (UFO and Tall Spindle Axe), each on 3 precocious rootstocks (Gisela 3, 5, and 6).  These include 9 sites in the United States (CA, OR, WA, MI, IN, IL, OH, NY, CO), 2 sites in Canada (BC, NS), and 1 site in Mexico (Chihuahua). The potential impacts of fruiting wall canopy architectures are extensive, ranging from more uniform light distribution, easier crop load-leaf area management, increased labor efficiency, more uniform spray coverage, and more feasible orchard covering systems.

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