2018 ASHS Annual Conference

Inter-annual variability in apple fruit storage disorders is associated with weather conditions during fruit development prior to harvest. Bioclimatic models for apple phenology, pests (insects and diseases), and storage disorders to assess risks associated with this weather variability were implemented in CIPRA, a computer system that uses real time weather data to assist crop producers in their daily decision-making process. The objective of this study was to update existing apple storage disorder models and develop new models based on fruit quality data collected over many years and sites in Eastern Canada. ‘Honeycrisp’ apples are quite susceptible to a number of storage disorders such as soft scald, soggy breakdown and bitter pit. ‘McIntosh’ and ‘Empire’ apple fruits show susceptibility to low temperature disorders such as vascular browning and core browning, respectively. Apple phenological data, weather data during fruit development and storage disorder incidences were collected over many years with the objective of identifying which weather parameters influence storage disorder incidences. Data from apple orchards were obtained on ‘Honeycrisp’ and ‘McIntosh’ in Ontario (2002-2006), and on ‘Honeycrisp’, ‘McIntosh’ and ‘Empire’ in Ontario and Quebec (2009-2017). The following weather data and parameters were measured or estimated: daily precipitations, maximum and minimum air temperatures, solar radiation, potential evapotranspiration and water balance, during six sub-periods of fruit development, expressed in days after flowering (DAF): 0-14, 15-29, 30-44, 45-59, 60-89 and 90-Harvest. Every year in each commercial orchard, apples were harvested at optimum maturity for storage and were evaluated immediately for fruit quality, including firmness, soluble solids content and starch index. They were then placed into air or controlled atmosphere storage for up to 10 months. The incidence of all storage disorders was assessed at the time of storage removals and 7 days later. All data for each storage disorder were analyzed using principal component analyses and stepwise linear regressions to establish the effect of weather after each sub-period of fruit development. For the years and sites of this study, results from these bioclimatic modelling activities show that weather during apple fruit development, as soon as 45 DAF, explains an important part of the observed variability of all storage disorder incidences in Eastern Canada. Such bioclimatic models will be very useful tools for apple producers in their marketing and storage strategies in order to provide high quality apples to their consumers.