Pre- and Postharvest Factors Control the Disease Incidence of Superficial Scald in the New Fire Blight Tolerant Apple Variety “Ladina”

Abstract

Superficial scald is a physiological disorder that develops during cold storage affecting apples and causes substantial market losses. Malus × domestica cv. Ladina, a new scab resistant and fire blight tolerant variety, commercialized in 2012, shows a physiological disorder similar to superficial scald after storage. Here, we used different pre- and postharvest approaches to characterize the occurrence of these superficial scald symptoms in Malus × domestica cv. Ladina. Over a period of seven years, fruits from multiple orchards were stored for five to seven months and the occurrence of superficial scald was assessed in fruits after cold storage and controlled atmosphere (CA) storage. Apples picked at different stages of ripeness within the same year differed in superficial scald development. Additionally, superficial scald differed significantly between years and locations, strongly suggesting that maturity at harvest, weather during the growing season, and orchard management play important roles in scald occurrence. Treatment with 1-methylcyclopropene (1-MCP) after harvest, and storage in a dynamically controlled atmosphere (DCA) significantly reduced the occurrence of superficial scald, whereas storage under ultralow oxygen concentrations (ULO) showed mild but not significant effects. Low calcium concentrations in the fruit flesh and peel were associated with stronger superficial scald occurrence.