Using Trichoderma spp. to Biological Control of Rhizoctonia solani Root Rot in Faba Beans

Root rot disease incited by Rhizoctonia solani, is one of destructive soil-borne diseases which constrains faba bean (Vicia faba L.) productivity. In the present research, pathogenicity of R. solani isolates was determined and potential of putative Trichoderma species were evaluated as a biological control in both in vitro as well greenhouse conditions. The most aggressive isolate of R. solani was determined with morphological characterization and sequencing of ITS rDNA. In vitro antagonistic potential of Trichoderma atroviride and Trichoderma asperellum against R. solani was evaluated by dual culture technique, and in greenhouse trials compared with a standard fungicide recommendation for comparison of efficacy. Both Trichoderma spp., strongly inhibited mycelia growth of R. solani in vitro, with inhibition ranging from over 85% for the most effective isolates. Trichoderma spp. applied to the soil under greenhouse conditions had significant influences on these trends significantly less damping-off and root rot disease incidence with an increase in the percentage of healthy surviving plants than the infected control. T. asperellum provided more efficient disease suppression than T. atroviride, whereas the chemical fungicide resulted in the greatest reduction of disease. Furthermore, Trichoderma-treated plants had higher activities of defense-related enzymes such as catalase, peroxidase and polyphenol oxidase which indicated the induction of systemic resistance. These results indicate that Trichoderma spp., mainly T. asperellum, can be a good alternative or supplement to chemical fungicides for the integrated disease management of R. solani-mediated root rot disease in V. faba L. under field conditions.