Fungicidal Activity of Plant Saponin CAY-1 for Fungi Isolated from Diseased Vitis Fruit and Stems

Abstract

Members of 10 fungal genera were isolated from diseased grape berries and stems collected in a local vineyard. These fungi were identified as Alternaria sp., Aspergillus japonicus, Cladosporium cladosporioides, Colletotrichum sp., Curvularia brachyspora, Epicoccum purpurascens, Greeneria uvicola, Nigrospora sphaerica, Trichoderma sp., Penicillium sclerotiorum and P. thomii. CAY-1, a fungicidal saponin in cayenne pepper (Capsicum frutescens) was significantly (p ≤ 0.05) lethal to the germinating (incubated 8 hr) but not the nongerminated (0 hr incubation) conidia of all the fungi except Alternaria and E. purpurascens at concentrations greater than 7.5 μM. CAY-1 was ineffective against the conidia of all the isolated fungi incubated 24 hr prior to mixing with the saponin. Results show that, in vitro, CAY-1 is lethal to these fungi only during their early germination cycle.