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Poster: Biology & Disease Mgmt: Biological Control


Natural products reduce grey mold of tomato caused by Botrytis cinerea
F. AHMED (1), A. Alvarez (1), B. Sipes (1) (1) university of hawaii at manoa, U.S.A.

Grey mold is the most important postharvest disease of tomatoes in Hawaii. Treatments with edible, natural products are needed to reduce losses and contribute to food sustainability. Based on the hypothesis that inhibition of Botrytis spore germination will significantly reduce postharvest losses, botanicals were tested for their effects on conidia. Ten Botrytis isolates from rotting tomato fruit were identified morphologically and confirmed by DNA sequence analysis. Leaves of candidate plants were frozen at -20C° and plant fluids were sterilized by passing through a 0.22 µm millipore. Extracts were evaluated by adding Botrytis spores (106/ ml) with sterilized malt extract broth to multi-well microplates. Changes in optical density measured at 6, 12, and 24 hours after inoculation were analyzed with Gen5 software. Capsicum chinense cultivars Datil and C. annuum Carnival completely inhibited fungal germination in preparations containing 30 and 40% leaf extract at all evaluation times. These extracts were superior to all other extracts tested. Extracts of Waltheria indica and C.frutescens had intermediate antifungal activity. Aloe vera, Tagetes patula and Capsicum annuum cultivars Red pepper, Criolla de cocina, New Mexico, showed no measurable antifungal activity. Extracts from the two most promising pepper cultivars, Datil and Carnival, are being evaluated as pre-harvest sprays in the greenhouse and as edible coatings on tomato fruit postharvest to reduce grey mold.