SUPPRESSION OF BULL’S EYE ROT OF APPLES AND GROWTH OF NEOFABRAEA PERENNANS BY SCALD CONTROL AGENTS DIPHENYLAMINE AND ETHOXYQUIN

Abstract

Postharvest dips of apples in diphenylamine or ethoxyquin, at concentrations that control storage scald, markedly reduced bull’s eye rot of fruit artificially inoculated with spores of Neofabraea perennans obtained from a local culture. Similar reduction in rot was obtained with the fungicide dodine, whereas the antioxidant propyl gallate was not effective.Comparative fungistatic tests indicated that dodine was a potent inhibitor of spore germination of N. perennans, and was only slightly less effective in suppressing hyphal growth. Diphenylamine inhibited hyphal growth to a greater extent than spore germination, while ethoxyquin inhibited hyphal growth only. Propyl gallate was essentially inactive in all tests. These data suggest that effectiveness of all three active materials against bull’s eye rot derives mainly from their ability to suppress hyphal growth.