"One bad apple ..." - preventing postharvest decays in apples CALS Impact Statement uri icon


  • Apples harvested in autumn are held for up to 10 months in refrigerated low-oxygen storages so that high-quality apples will be available in grocery stores throughout the year. The fungal pathogen Penicillium expansum causes decays in stored apples. This pathogen was controlled with benzimidazole fungicides from the early 1970s through the mid-1990s, but then fungicide-resistant strains of the pathogen resulted in mounting losses to P. expansum. Epidemiological studies in commercial orchards, storages, and apple packing houses showed that P. expansum was invading apple fruit via their stems during long-term storage and that high boron concentrations in fruit increased susceptibility to postharvest decay. Inoculum that originated in the field each year was relatively unimportant compared to much larger quantities of inoculum that cycled from year to year on wooden and plastic storage bins. Apple growers informed of these results reduced boron fertilizer regimes so as to minimize fruit susceptibility to decay and storage operators adopted sanitation measures that reduced inoculum levels on bins. One large packinghouse installed a $75,000 automated bin washer to decontaminate bins as they are emptied in the packing house. Results from this work have helped to maintain profitability of the New York apple industry.