Influence of food additives on the control of postharvest rots of apple and peach and efficacy of the yeast-based biocontrol product Aspire

The effects of calcium propionate, sodium bicarbonate, and sodium ethylenediamine-tetraacetic acid (EDTA) on postharvest pathogens of apple and peach, and on improving the efficacy of the biocontrol product Aspire were evaluated. All three materials had a distinct inhibitory effect on the radial growth of Botrytis cinerea and Penicillium expansum in vitro. The inhibitory effect increased with the concentration of each material. When tested on apple, sodium bicarbonate and EDTA exhibited only a curative effect (control of pre-existing infections) against infections caused by B. cinerea. Ca-propionate, however, provided both protective and curative effects against infections caused by B. cinerea. In the case of P. expansum, sodium bicarbonate, at concentrations up to 0.4% and EDTA, at all concentrations tested, failed to provide any curative or protective activity against infections by P. expansum on apple. Sodium bicarbonate at 2% was the most consistent in providing a measure of fungicidal activity when used alone. In combination with Aspire, 2% sodium bicarbonate exhibited a consistent ability to significantly enhance its biocontrol performance (curative and protective effect) against Botrytis and Penicillium rot in apple and Monilinia and Rhizopus rot in peach. Based on these results, it appears that the use of additives, such as sodium bicarbonate, is a useful approach to improve the efficacy of yeast antagonists used for postharvest disease control. (C) 2002 Elsevier Science B.V. All rights reserved.