Risk of Storage Disorders in Apples for 2020-21 Storage Season

CIPRA is a computer-based program developed by the research team of Dr. Gaétan Bourgeois (AAFC-QC) that uses weather data to predict the risk susceptibility of apples to specific storage disorders (Bourgeois, DeEll, and Plouffe). According to CIPRA models using weather data until September 15, 2020 from Delhi (Norfolk County, ON), there is little risk of chilling-related flesh browning disorders developing in apples here during the current storage season (Figure 1).

Bar chart showing the risk of developing chilling related disorders since 1991. The Y axis shows browning index up to 100. Browning index for 2020 is at 0.
Figure 1.  Risk of developing chilling-related flesh browning disorders during the past 30 years (1991-2020), for the region of Simcoe-Delhi (Norfolk County), Ontario.
(Graph supplied by D. Plouffe, AAFC-QC)

Using specific models for bitter pit and soft scald development, CIPRA with weather data from Environment Canada shows varying risk susceptibility around Ontario (Table 1). East of Toronto has the highest risk for both bitter pit and soft scald during storage this season, while Collingwood area around the Georgian Bay has the lowest risk.

Table 1. Risk of developing bitter pit or soft scald in four apple producing regions of Ontario

Risk %
Bitter pit
Risk %
Soft scald
* Data supplied by D. Plouffe, AAFC-QC

Regardless of growing season and annual risk susceptibility, it is important to use the recommended storage temperatures and regimes for specific apple cultivars.  ‘Honeycrisp’, ‘Empire’, and ‘McIntosh’ are especially susceptible to chilling-related disorders (i.e. soft scald, soggy breakdown, flesh browning, low temperature breakdown, core browning) and therefore, symptoms can develop by using lower than optimum storage temperatures in any year.  Late harvested apples are also more prone to developing chilling-related disorders, such as flesh browning in ‘Empire’ or soft scald and soggy breakdown in ‘Honeycrisp’.

At the time of writing, there has already been plenty of soft scald observed this season in ‘Honeycrisp’ stored below the recommended temperature of 3oC, as well as in those without conditioning at 10oC prior to storage at 3oC.  Therefore, it is important to manage your storage regimes and apple marketing accordingly.

Dr. Jennifer DeEll
Dr. Jennifer DeEll

Fresh Market Quality Specialist – Horticulture, OMAFRA