Etiology of leaf spot diseases of ivy gourd (Coccinia grandis (L) Voigt) and their management

Abstract

A study on various aspects of leaf spot disease of ivy gourd was conducted at College of Horticulture, Vellanikkara during 2002-2003. Etiological studies revealed that Cercospora cocciniae Munjal, Lall and Chona, Colletotrichum gloeosporioides (Penz.)Sacc, and Alternaria alternata Fr.Keissler were the main pathogens causing different leaf spot diseases of ivy" gourd. Colletotrichum gloeosporiotdes was found as the main pathogen causing spots on fruits of ivy gourd. Among the nineteen ivy gourd genotypes tested eight genotypes were found highly resistant to different leaf spot diseases. For Cercospora and Colletotrichum leaf spots, low temperature, high humidity and high rainfall were found to favour infection, so they were prevalent in rainy season. Alternaria infection was noticed during summer months favouring high temperature, moderate relative humidity and rainfall. From the in vitro evaluation conducted for testing the efficacy of fungicides and botanicals, 0.2 per cent copper oxychloride, copper hydroxide, captan and mancozeb, 10 per cent leaf extract of Lantana and Adathoda, bulb extract of garlic and 0.2 per cent neem oil were selected. The fungal antagonists Trichoderma viride, T. harzianum and the bacterial antagonist, Pseudomonas jluorescens were " also selected for pot culture studies. During the pot culture experiment, copper oxychloride, copper hydroxide(both at 0.2 per cent), garlic (l0 per cent) and neem oil (0.2 per cent) and the antagonists, Trichoderma viride (0.4 per cent) and P. jluorescens (0.2 per cent) were found effeotive against leaf spot diseases and selected for field evaluation. From disease management study conducted in the field, 0.2 per cent copper oxychloride, co~per hydroxide, 10 per cent garlic and 0.4 per cent Trichoderma viride were found equally effective in controlling both leaf and fruit infection in ivy gourd.