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Tree growth and crop yield of five cultivars in two organic apple orchard systems in Vermont, USA, 2006-2013

Bradshaw, T. L., Berkett, L. P., Moran, R. E., Garcia, M. E., Darby, H. M., Parsons, R. L., Kinglsley-Richards, S. L., Griffith, M. C., Bosworth, S. C., Gorres, J. H.
Acta horticulturae 2016 no.1137 pp. 299-306
apples, arthropods, crop yield, cultivars, decision making, economic performance, growers, horticulture, orchards, organic foods, organic production, production technology, tree growth, trees, Vermont
Adequate tree growth and crop yield are essential to the long-term success of orchard systems and these are often challenges when systems are managed organically in the northeastern US. The objective of this project was to evaluate horticultural performance of five apple cultivars ('Ginger Gold', 'Honeycrisp', 'Liberty', 'Macoun', and 'Zestar!') grown under organic management in both a newly planted orchard (Orchard 1) and in a top-grafted established orchard (Orchard 2). Results summarize tree growth and crop yield of each cultivar in both production systems over eight seasons from 2006-2013. There were no differences in tree survival among the cultivars in Orchard 1, where survival ranged from 97.8 to 100%. However, only 65.8% of 'Macoun' and 63.2% of 'Zestar!' trees survived in Orchard 2. There were cultivar differences in tree growth parameters within the two orchard systems. However, in both orchards, 'Ginger Gold' had the greatest, or was among the cultivars with the greatest shoot growth, tree height, and tree width. 'Ginger Gold' was also among the highest-yielding cultivars in all years in Orchard 1, and in three of six years in Orchard 2. 'Macoun' had among the lowest crop yield in most years in both orchards. 'Ginger Gold' and 'Honeycrisp' had among the highest cumulative yield per tree in Orchard 1. 'Ginger Gold' in Orchard 2 had the highest cumulative yield per tree of all cultivars. These results combined with analyses of disease and arthropod incidence and economic performance comparing the five cultivars within each orchard system will aid growers in their decision-making to select cultivar(s) and orchard establishment methods for an organic production system.