Control of postharvest fungal rots on citrus fruit and sweet cherries using a pomegranate peel extract

A pomegranate peel extract (PGE) was evaluated as a natural antifungal preparation for the control of postharvest rots. In vitro trials revealed a strong fungicidal activity against germination of conidia of Botrytis cinerea, Penicillium digitatum and Penicillium expansum. Almost complete inhibition of all fungal spore germination was achieved after 20 h of incubation with PGE. PGE was very effective in inhibiting decay following artificial inoculations of lemons by P. digitatum and Penicillium italicum, grapefruits by P. italicum and apples by P. expansum . At concentrations of 1.2 and 12 g/l complete inhibition of infection was achieved in the majority of host pathogen combinations. Furthermore, it was also effective in reducing natural rots under semi-commercial conditions on both sweet cherries and lemons: on cherries Monilinia laxa and B. cinerea rots were reduced by 61.0% (cv. Bigarreau Moreau) and 95.6% (cv. Giorgia), respectively, and on lemons 87.8% reduction of total rot was achieved. PGE treatment showed residual effect as it was effective in inhibiting infections made at 6, 12, and 24 h after the application of the extract in fruit wounds. Additionally, PGE exhibited curative activity and reduced the incidence of rots when it was applied 6 and 24 h after inoculation. Considering that PGE was extracted and stabilized using safe chemicals (food grade ethanol and citric acid) and that it did not have any apparent phytotoxic effect on treated fruit, PGE proved to be effectively eco-friendly and safe control mean for postharvest rots of fruit.