The large tree size, and delicate nature and small size of the fruit, makes production of sweet cherries among the most traditionally labor-intensive tree fruits. Great improvements in orchard efficiencies have been achieved over the past two decades, prompted by the development of precocious, vigor-controlling rootstocks such as the Gisela (Gi) series. Recent training systems research has focused on canopy architectural designs that improve various orchard efficiencies, including: 1) light interception and distribution for minimization of shade; 2) bloom, fruit development and ripening for more uniform fruit harvest; 3) balanced crop load management for achieving high fruit quality; 4) simplified strategies for fruitwood development and maintenance to reduce hand-pruning labor; 5) partial mechanization to reduce pruning and harvest labor; 6) utilization of protective orchard covers to mitigate the risk of crop damage from rain, hail, frost, and wind; and 7) better spray coverage for protection from insect pests and diseases. Across several sites in North America, the NC140 regional research project has evaluated the performance of three sweet cherry cultivars on dwarfing (Gi3), semi-dwarfing (Gi5), and semi-vigorous (Gi6) rootstocks trained to “three-dimensional” and “two-dimensional” (planar) canopy architectures ver nine years to date. The planar Super Slender Axe (SSA) training system had the highest early yields on a per tree and per orchard basis, but the planar Upright Fruiting Offshoots (UFO) training system sustained higher cumulative yields upon reaching maturity. The three-dimensional Tall Spindle Axe (TSA) trees had higher early yields than those trained to the three-dimensional Kym Green Bush (KGB) training system, but the KGB trees achieved nearly comparable cumulative yields. Fruitwood renewal strategies are critical for maintenance of yields and fruit quality. Profitable yields of high quality fruit are achievable for each of the canopy architectures, but each also has specific advantages and challenges, including suitability for specific rootstocks and cultivars. These are discussed, including comparisons of the two- vs. three-dimensional canopy architectures developed as single leader (SSA vs. TSA) and multiple leader (UFO vs. KGB) training systems. The advantages of utilizing the natural light interception efficiencies and growth habit of sweet cherry in the simplified structure of UFO-style planar canopy architectures is expanding beyond sweet cherries to many other major trees fruits around the world as well.
Keywords: Prunus avium, high density, canopy architecture, fruiting wall