Rootstock, Training System, and Bud Management Affect Establishment of High Density Sweet Cherry Training Systems

Production of fresh market sweet cherries (Prunus avium L.) requires high labor inputs and incurs significant risks, such as frosts, rain-induced fruit cracking, bird damage, etc. Research to improve orchard efficiencies, and to simplify and reduce tree structure and stature, is key to improving orchard economics. The development of high-density fruiting wall canopy architectures has the potential to lower costs of protection (from birds or rain), provide more efficient use of space, reduce labor costs, and facilitate better light and spray penetration, thereby improving fruit quality, consistency, and profitability. In this study, we examined four novel training systems on three precocious rootstocks (Gisela 3 and 5 are dwarfing, Gisela 6 is vigorous) to determine how they interact during early orchard establishment of ‘Benton’ and ‘Rainier’ sweet cherry trees. The training systems include the UFO (an oblique leader with fruiting upright shoots), the KGB (a multiple leader bush with fruiting upright shoots), the SSA (a single leader with short lateral fruiting shoots), and the TSA (a single leader with longer, branched lateral fruiting shoots). The objective is to better understand the factors and the interactions that influence early development of those shoots that ultimately will form the first fruiting sites. Bud management at planting, rootstock genotype, and canopy training system variably affected spatial distribution of new shoots, number of shoots per tree, trunk cross-sectional area (TCSA), and total shoot length. Shoot numbers ranged from 3 to 38 and were affected most by training system, being greatest for the KGB averaging 18.2 and TSA averaging 16.9. Bud management at planting also affected shoot formation; targeted bud selection/removal resulted in new shoot distributions that were 7% and 8% closer to “ideal” targets for the UFO and TSA canopies, respectively. Total growth was most influenced by training system and rootstock, with total shoot length and TCSA being greatest for trees trained to the TSA at 593 cm and 4.8 cm², respectively, and Gisela 6 at 579 cm and 4.4 cm², respectively. How this growth during the year of establishment affects the populations of initial spur and non-spur fruiting sites in 2011, and the anticipated first commercial yield potential in 2012, will be discussed.