Role of Organic Amendments for the Management of Black Scurf of Potato Caused by Rhizoctonio Solani (Kuhn)

Abstract

Potato (Solanum tuberosum Linn.) is one of the important crop and the fourth largest grown crop after rice, wheat and maize in the world. Black scurf is one of the most wide spread disease and found in all potato growing areas of the world. The typical symptoms are characterized by appearance of black coloured sclerotia on the tuber surface and brownish necrotic lesions on stem and stolon. The pathogen was isolated from naturally infected tubers and the fungus was purified. In the pathogenicity test the symptoms were found on tuber, stem and stolon also. Efficacy of three species of Trichoderma was evaluated by dual culture against Rhizoctonia so/ani and it was observed that T. hamatum was more capable of suppressing the growth of the pathogen followed by T. harzianum and T. viride. The efficacy of antagonist (T. harzianum) was also further evaluated against the pathogen and it was observed that T. harzianum produced both volatile and non-volatile compounds which inhibit the growth of R. so/ani. In bio assay two chemicals were tested against the pathogen in which Bavistiri obtained hundred percent inhibition of pathogen at all concentrations while Boric acid was less effective. The Vermicompost and neem cake found most effective against R. so/ani while in the case of FYM it was increasing the growth of the pathogen in vitro condition. The efficacy of organic amendments (Vermicompost, Neem cake and Farm Yard Manure) was evaluated as soil application alone or in combination with the antagonist (T. harzianum). The Vermicompost and Neem cake both found effective in reducing the Black Scurf Disease Index (BSDI) while FYM was less effective in controlling the black scurf, stolon and stem canker. The Vermicompost and Neem cake also promote the growth of the plant i.e. increasing the shoot length, seed size and formation of tubers per plant was increased. The yield was also increased by the Vermicompost and Neem cake. Integration of organic amendments may b~ beneficial in reduction for soil-borne pathogen in potato crop.