Studies on Leaf Blight Disease of Medicinal Plants (Piper longum, Tylophora indica, Hibiscus subdariffa) in Lower Gangetic Plains of West Bengal, India

Herbal medicinal plants are in great demand for their use in food preparations, pharmaceuticals, cosmetic and beauty aids. But its availability is reduced every year due to attack of fungal disease i.e. leaf blight. Therefore an experiment was conducted to gather the knowledge about the future management aspect of this disease. Here three medicinal plants viz, Piper longum, Tylophora indica and Hibiscus subdariffa were planted and observed the disease throughout year. The characteristic symptoms of the disease along with causal organisms (Colletotrichum gloeosporioides- Piper longum, Sclerotianum rolfsii- Tylophora indica, Fusarium sp- Hibiscus subdariffa) were recorded. In the seasonal study, the lowest disease incidence and severity of the disease were observed in the month of August and higher in June. Hibiscus subdariffa showed less disease incidence (15.33%) and severity (6.11%) at initial stage (August) and 67.33% & 42.46% respectively at peak period (June). But Piper longum and Tylophora indica showed higher disease incidence and severity at the same times. All these pathogens were isolated in PDA medium from the infected parts of plants and confirmed their pathogenicity. The cultural characteristics along with their micrometric measurement of spores were recorded in four different media (PDA, CZA, OMA and MMA). Colletotrichum gloeosporioides was found to grow better in PDA (9.0 cm) along with high dry weight (1.47g) and lowest growth in maize meal medium (4.8cm). In Sclerotium rolfsii, highest radial growth (9.0cm) and dry weight (1.48g) were observed in maize meal medium but no growth in Czepek’dox. Fusarium sp showed highest radial growth (8.3 cm) and dry weight (1.34 g) in czepek dox and lowest in maize meal agar medium (4.4cm).