Biological control of bean root rot disease caused by Rhizoctonia solani under green house and field conditions

摘要

This study was carried out to evaluate the efficiency of the biocontrol agents Trichoderma harzianium, Glomus intraradices and Azotobacter chroococcum to protect bean, Phaseolus vulgaris L. plants against Rhizoctonia solani, causative agent of root rot under different conditions. Results obtained showed that the disease was distributed in all bean cultivated area of Babylon city-Iraq and R. solani was detected in most tested samples. It has been found that R. solani had effects on bean seed germination and plant growth. Result of differential hosts revealed that R. solani isolates obtained belong to anastomosis groups 4 (AG-4) and this confirmed by the result of the dual culture test on PSA medium. Four isolates of Azotobacter chroococcum, isolated from wheat, bean and sesban, Sesbania sesban L. showed high antagonistic activity against the higher pathogenic isolate of R. solani (RS-3) on PSA medium. Arbuscular mycorrhizal, G. intraradices significantly reduced the disease incidence and severity in bean plants, The combination A. chroococcum with G. intraradices found to be more effective, than each of them separately, in decreasing disease incidence and severity under green house and field conditions. T. harzianium exhibited high activity in controlling the disease and increasing yield. All biocontrol agents used in this study improved plant growth and increased yield. The biocontrol agents may play an essential role in management of root rot diseases.