Insights for orchard design and management using intensive sweet cherry canopy architectures on dwarfing to semi-vigorous rootstocks

Abstract

Coordinated intensive sweet cherry canopy architecture/rootstock trials were planted in 2010 across North America at 13 diverse sites under the NC140 regional rootstock research project. The diverse canopy architectures include two “three-dimensional” canopies: 1) a single central leader with 15 to 20+ lateral fruiting branches in a conical canopy (tall spindle axe, TSA) and 2) a multiple leader bush-like canopy with 8 to 15 upright narrow fruiting mini-leaders (Kym green bush, KGB); plus two “planar” canopies: 1) a single central leader with 20 to 30+ short lateral fruiting shoots, planted closely, pruned severely, and aligned to form a narrow fruiting wall (super slender axe, SSA), and 2) an oblique cordon-like horizontal leader with 7 to 10 upright fruiting mini-leaders aligned in a narrow fruiting wall canopy (upright fruiting offshoots, UFO). The rootstocks are ‘Gisela 3’ (Gi3, dwarfing), ‘Gisela 5’ (Gi5, semi-dwarfing), and ‘Gisela 6’ (Gi6, semi-vigorous). After 7 years, the Michigan trial (with the scion ‘Benton’) is the most vigorous trial site. Each canopy architecture has advantages and disadvantages with respect to precocious yields, cumulative yields, ease and cost of establishment, harvest labor, and potential for partial mechanization for pruning. Projected orchard yields have been highest for trees on the dwarfing and semi-dwarfing Gi3 and Gi5 rootstocks across all canopy architectures, and highest through 7 years on the UFO and TSA training systems. Fruit quality has not varied significantly by canopy architecture or rootstock. However, renewal of fruiting wood, one key to longevity of intensive orchards, has been problematic on some trees on the rootstocks that impart lower vigor and higher yields. These trials have contributed significant insights for improved orchard designs for the next generation of light- and labor-efficient canopy architectures for high quality sweet cherry production systems across a range of rootstock vigor traits.