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Research Journal of Applied Sciences

Year: 2013  |  Volume: 8  |  Issue: 1  |  Page No.: 72 - 81

Evaluating the Efficacy of Trichoderma Isolates and Bacillus subtilis as Biological Control Agents Against Rhizoctonia solani

Hamdia Z. Ali and Kalaivani Nadarajah


The aim of this study is to determine the effectiveness of the Trichoderma isolates as a biological control agent against Rhizoctonia solani Kuhn. In vitro tests of antagonistic activity and ability of Trichoderma isolates against R. solani via the dual culture technique showed that isolates 6, 7, 8, 20, 13, 22 and 17 had high antagonistic activities with reduced radial growth of pathogen. The Trichoderma isolates were used in control experiment under greenhouse conditions where inoculation with Trichoderma isolates 2, 4, 7 and 11 were effective in inducing significant increase in pre and post emergence seedlings (4.33, 4.33, 4.33 and 8.33%) and also contributed towards an increase in seed germination (4.67, 4.67, 4.33 and 4.33%). The suppression results of Trichoderma isolates 2, 7 and 9 on R. solani growth showed disease incidence of approximately 33.33% while disease severity results for the same isolates were 20, 15.67 and 20%, respectively. These readings recorded a significant difference (p = 0.05) than those obtained when the soil was artificially inoculated with R. solani only where the observed values for disease incidence and severity were 100 and 77.67%, respectively. The combination treatment between Trichoderma isolates and Bacillus subtilis showed all Trichordema isolates were able to reduce pre and post-emergence of disease in seedlings in control experiment (p = 0.05). In the combination treatment; isolates 2 and 7 had the highest reduction in disease incidence (both 11%) and severity (both 4.33%) after 60 days post transplanting; the concoction appeared to enhance the growth of plants. Trichoderma isolates 2, 7, 8, 9, 11 and 21 in combination with B. subtilis had excellent suppression of pre (8.67, 8.33, 13, 8.67, 8.67 and 8.67%) and post (9, 8.67, 9.33, 14, 9 and 14%) emergence of disease in R. solani inoculated soil. This shows an overall reduction of disease incidence of between 22-33% and severity of 15.33-22% when the Trichoderma isolates were used in combination with B. subtilis to suppress R. solani infestations.