ALTERNATIVE METHODS OF SCALD CONTROL IN GRANNY-SMITH APPLES

Experiments using 'Granny Smith' apples (Malus x domestica Borkh) aime d to evaluate possible alternatives to diphenylamine (DPA). These expe riments were designed to consider the effect of low ethylene in storag e atmosphere, ''Semperfresh'' (a sucrose ester carboxymethylcellulose coating), ascorbic acid, ascorbyl palmitate (a lipid soluble derivativ e of ascorbic acid), citric acid and ''Aerophos P''. Low ethylene in t he storage atmosphere (approximately 1 mu l 1(-1)) did not reduce scal d incidence or severity in apples stored in controlled atmosphere (0.5 -2.5% Co-2:1.3-3.1% O-2). Semperfresh reduced scald incidence and seve rity appreciably when apples were stored in controlled atmosphere (1.6 % CO2:1.4% O-2) for 43 weeks but not when apples were stored in air. F urthermore, Semperfresh failed to improve the performance of low conce ntrations 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 a dditional scald reduction. Ethanol reduced scald in susceptible apples grown in northern Victoria but none of the other compounds was effect ive.