Studies on pod and collar rot of soybean caused by Fusarium semitectum (Berk. and Rav.)
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Date
2005-07
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Pod and collar rot of soybean caused by F. semitectum is one of the most important disease of soybean. The present investigation was undertaken to study the cultural characters of the pathogen, pathogenicity and efficacy of fungicides and bio-agent against the test pathogen in-vitro. Depressed, water soaked, cream coloured lesions were observed on cotyledons and hypoctyles. Later on, these lesions turned dark brown to black. Cultures appear peach coloured from below. Hyphae were septate, macroconidia abundant, microconidia rare. Chlamydospores globose, formed singly or in chains. Among the media tested, Corn meal agar supported best growth and sporulation of the pathogen at 25± 1°C. The pathogen was able to grow at different temperature levels viz., 15 to 40°C optimum being at 25°C. The pathogen was able to grow in a wide range of pH between pH 4.0 to pH 9.0. Poor fungal growth was observed at pH 4.0 and pH 9.0, optimum pH being at 6.5. Culture filtrate of the fungus reduced root length, shoot length and germination percent. Carbendazim was found most effective in inhibiting the radial growth of the pathogen at 40 and 50 ppm followed by Topsin-M while Vitavax was found least effective in checking the growth. Trichoderma harzianum inhibited the growth of F. semitactum by 50 per cent after 6th day and later on, overlapped. Diurnal light fluctuation of 12-12 hours found best for growth and sporulation of pathogen.
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