Use of essential oil as botanical-pesticide against post harvest spoilage in Malus pumilo fruits

During antifungal screening of the essential oils of some angiospermic plants, oil of Cymbopogon flexuosus showed potent bioactivity against dominant post harvest fungal pathogens. The minimum bioactive concentrations with fungicidal action of the oil was found to be 0.2 mul ml(-1) for Alternaria alternata, 0.4 mul ml(-1) for Aspergillus flavus, A. fumigatus, A. niger, A. parasiticus, Cladosporium cladosporioides, Colletotrichum capsici, C. falcatum, Curvularia lunata, Fusarium cerealis, F. culmorum, F. oxysporum, F. udum, Gloeosporium fructigenum, Penicillium expansum, P. italicum, P. implicatum, P. digitatum, P. minio-luteum, P. variable, and 0.5 mul ml(-1) for Botrytis cinerea, Helminthosporium oryzae, H. maydis, Phoma violacea, Rhizopus nigricans. The oil exhibited potency against heavy doses (30 mycelial disc, each of 5 mm in diameter) of inoculum at 1.0 mul ml(-1) concentrations. The bioactivity of the oil was thermostable up to 100degreesC and lasted up to 48 months. The oil preparation did not exhibit any phytotoxic effect on the fruit skins of Malus pumilo up to 50 mul ml(-1) concentrations. In vivo trials of the oil as a fungicidal spray on Malus pumilo for checking the rotting of fruits, it showed that 20 mul ml(-1) concentration controls 100% infection by pre-inoculation treatment, while in post-inoculation treatment, 30 mul ml(-1) concentration of fungicidal spray was required for the 100% control of rotting. The fungicidal spray was found to be cost effective (INR 15/1), has long shelf life (48 month) and was devoid of any adverse effects. Therefore, it can be used as a potential source of sustainable eco-friendly botanical pesticide, after successful completion of wide range trials.