Alternative methods of scald control in ‘Granny Smith’ apples

Abstract

SummaryExperiments using ‘Granny Smith’ apples (Malus × domestica Borkh) aimed to evaluate possible alternatives to diphenylamine (DPA). These experiments were designed to consider the effect of low ethylene in storage atmosphere, “Semperfresh” (a sucrose ester carboxymethylcellulose coating), ascorbic acid, ascorbyl palmitate (a lipid soluble derivative of ascorbic acid), citric acid and “Aerophos P”. Low ethylene in the storage atmosphere (approximately 1 µl l-1) did not reduce scald incidence or severity in apples stored in controlled atmosphere (0.5–2.5% Co2:1.3–3.1 % O2). Semperfresh reduced scald incidence and severity appreciably when apples were stored in controlled atmosphere (1.6% CO2:1.4% O2) for 43 weeks but not when apples were stored in air. Furthermore, Semperfresh failed to improve the performance of low concentrations of diphenylamine. Ascorbic acid reduced scald incidence and severity when apples were stored in controlled atmosphere for 43 weeks but did not reduce scald consistently when apples were stored in air. Repeated applications of ascorbic acid early in storage provided no additional scald reduction. Ethanol reduced scald in susceptible apples grown in northern Victoria but none of the other compounds was effective.