Studies on charcoal rot of sesame caused by Macrophomina phaseolina (Tassi) Goid
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Date
2017
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CCSHAU
Abstract
The charcoal rot disease caused by Macrophomina phaseolina (Tassi) Goid. is the most serious soil and seed borne fungal disease which causes maximum damage in sesame (Sesamum indicum L.). The present investigation was undertaken to study the effect of M. phaseolina on seed germination and seedling vigour of sesame genotypes and to manage the disease through host resistance, fungicides and bio-agents. The pathogen significantly reduced the per cent germination, plumule and radicle length, fresh and dry weight of seedlings and cumulative reduction in seedling vigour index in all the seven genotypes under both seed and soil inoculation technique. Out of one hundred germplasm lines screened for their relative resistance against charcoal rot disease in field under natural sick plot conditions, none of the lines showed resistance reaction, however, five lines showed moderately resistant reaction, fifty five lines showed moderately susceptible reaction, thirty eight lines showed susceptible reaction, while two germplasm lines showed highly susceptible reaction against charcoal rot disease. Efficacy of fungicides in vitro against M. phaseolina showed that thiram + carboxin and thiram completely inhibited mycelial growth up to 100 per cent at 400 ppm concentration followed by carbendazim, tebuconazole and captan showing respective mycelial growth inhibition of 97.17, 91.84 and 82.32 per cent even at 1000 ppm concentration. However, carboxin was found least effective at lower concentrations but gave comparable result to thiram + carboxin and thiram at 400 ppm concentration. Evaluation of bio-agents against M. phaseolina in vitro revealed that Trichoderma viride showed maximum antifungal activity with 71.17 per cent inhibition of mycelial growth followed by T. harzianum (63.58%), while the bacterial agent P. fluorescens inhibit 37.83 per cent of mycelial growth. Seed treatments with fungicides and soil inoculation with bio-agents significantly reduced the disease incidence. Maximum disease control was achieved by thiram + carboxin @ 2g/kg seed which controlled 77.16 per cent followed by thiram @ 2g/kg seed (69.02%). In case of bio-agents, T. viride showed maximum disease control (54.40%) followed by T. harzianum (40.90%) in comparison to control.
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