Control of postharvest diseases of sweet cherry with ethanol and hot water

Abstract

Complete inhibition of the germination of spores of Penicillium expansum occurred after 10 s exposure to 40% ethanol or more at ambient temperature, while spores of Botrytis cinerea were completely inhibited by 30% ethanol or more. Mortality of the spores of P. expansum and B. cinerea in heated 10% ethanol was higher than in water at the same temperatures. Immersion of naturally inoculated fruit in 20, 30, 40, or 50% ethanol reduced the decay present after storage for 10 days at 20degreesC similarly and by approximately 60-85%. Immersion of fruit that had been inoculated with the spores of P. expansum and B. cinerea reduced decay by both pathogens after storage for 30 days at 0degreesC and 5 days at 20degreesC when 30% or higher concentrations of ethanol were used. The incidence of decay after immersion in water alone for 30 s at 24, 50, 55, or 60degreesC was 57.7, 44.7, 46.2, and 35.7%, respectively, while 10% ethanol at these temperatures the decay incidence to 52.2, 33.9, 32.8, or 14.7%, respectively. Water treatments at 50, 55, or 60degreesC alone were not effective against P. expansum, while their efficacies were significantly increased by the addition of 10% ethanol. The most effective treatment was immersion in 10% ethanol at 60degreesC. Ethanol treatments at 20, 30, 40, or 50% and water treatments at 55 or 60degreesC significantly reduced natural fungal populations on the surfaces of fruit in all of the experiments. Addition of 10% ethanol to water significantly increased the efficacy of water in reducing the fungal populations at elevated temperatures. None of these treatments caused surface injuries to the fruit or adversely affected stem colour.