The NC140 regional research project on sweet cherry systems and rootstock was established at Crist Farms in Walden, NY in 2010. The purpose of the trial is to study the influence of training system, rootstock vigor, and growing conditions (site) on annual fruiting unit growth, yield, and fruit quality. At the Crist Farms site, a cherry variety Regina is trained to four high density training systems: Slander Spindle Axe (SSA), Upright Fruiting Offshoots (UFO), Tall Spindle Axe (TSA), and Kym Green Bush (KGB). The cherry trees were grafted to Gisela rootstocks series: Gi.3 (dwarfing, 30-45% of standard), Gi.5 (semi-dwarfing, 50-65% of standard) and Gi.6 (semi-vigorous, 75-90% of standard).
The objectives of using the four training systems in the study are:
- changing the acrotonic growth habit of sweet cherry, and thus improving light distribution lower in the canopy;
- inducing precocity and improving early yield potential;
- developing a minimal permanent trunk;
- performing annual renewal of a portion of the fruiting wood, which is one of the keys to producing high quality fruit over several decades;
- allowing orchard work to be conducted from the ground.
During the bloom 2016 we have performed a “whole tree renewal”, which comprised of removing the most vigorous (largest diameter) fruiting branches by stubbing them back to the lowest possible visible basal bud. For this purpose, only one out of three trees per rep was selected and the related data were used to investigate the effect of tree renewal pruning practice on yield, fruit quality and vegetative growth.
The trees have started bearing fruits for the first time in 2015. The evaluation of yields and fruit quality in that year has shown an expected low fruit production (< 10 kg/tree), with TSA having the highest yields on all three rootstocks, followed by UFO, KGB and SSA.
In 2017, TSA has continued to produce the highest yield and have bigger TCSA. None of the tested rootstocks had an impact on yield, but Gi.6 has increased trunk size and fruit weight.
The trees that were renewed by removing the most vigorous branches has born very low yield in 2017, up to 1.5 kg per tree. The assessment of the trial production, fruit quality and health status of the trees will continue until 2020.
You can find more about this trial and cherry training systems here.