Research Report: Fruiting Wall Production Systems For Apricots And Nectarines

Year 5 (2019) of a Six-Year Duration Project (2015-2020):

The overall objective of this project is to develop, refine, and evaluate two complementary orchard technologies, fruiting wall canopy architectures for stone fruit production and high tunnel protective covering structures, to examine their potential for improving Midwest growers’ ability to sustainably produce and market high value specialty stone fruit crops like peaches, nectarines, and apricots. The first phase of this work was completed in 2016 at the MSU Clarksville Research Center (CRC) by concluding the evaluation of four potential intensive canopy architectures for stone fruits: Tall Spindle Axe (TSA), Palmette (PLM), Upright Fruiting Offshoots (UFO), and a modified Super Slender Axe (SSA) imposed selectively on nectarines (TSA, SSA, UFO), and apricots and plums (PLM, SSA, UFO). UFO-training was best suited for the spur-bearing habit of apricots and plums, while SSA-training appeared to be promising for nectarines (and peaches).

In 2017, next generation trials were established with nectarines and apricots at the MSU Southwest Michigan Research and Extension Center (SWMREC). ‘Robada’ and ‘Sugar Pearl’ apricot trees (on apricot and myrobalan seedling rootstocks, respectively) are being trained as a bi- cordon UFO vertical fruiting wall in two 200 x 24 ft multi-bay high tunnels, one with 2 tree rows and one with 3 tree rows. Due to poor nursery tree establishment growth in 2017, the canopies were allowed to grow untrained through summer 2018, at which time the two most uniform leaders were selected and tied horizontally to the bottom trellis wire. This formed the two cordons from which upright fruiting offshoot leaders were developed in 2019 (Fig. 1). Average offshoot length in 2019 was 0.9 m (3 ft), and average number of offshoots per tree was 29, which will be thinned to experimental target numbers and spacing in 2020. The first flowering and yield data collection also is anticipated in 2020. Mortality was significant in 2019, following a late December-early January rapid climatic transition from mild to very cold temperatures.