The action of phorone and other compounds in controlling superficial scald of apples

A new inhibitor of superficial scald, phorone (2,6-dimethylhepta-2,5-dien-4-one) is reported. Phorone reduced scald on ‘Granny Smith’ apples when applied by injection or as a vapour. Phorone was found to limit the accumulation of α-farnesene during storage and the amounts of conjugated triene oxidation products derived from α-farnesene. Monoterpenes also reduced α-farnesene, oxidation products and scald, but these compounds were less effective than phorone. In contrast, diphenylamine had little effect on the amount of α-farnesene in the fruit but it prevented the autoxidation of α-farnesene and controlled scald.