Damping-off and root-rot diseases in bean caused by Rhizoctonia solani Kuhn are considered the most destructive diseases. Rhizoctonia solani isolates were pathogenic and varied in their virulence on bean plants (Nebraska cv.) in vivo. The isolate No. 7 of R. solani obtained from Sakha was the most aggressive one, which gave the highest percentages of pre-and post-emergence damping-off (66.7 and 26.7%), respectively. All Bioagents viz. Trichoderma harzianum, T. aureoviride, Bacillus subtilis and B. amyloliquefaciens, plant extracts of garlic, onion and neem, biocides viz. Bio-Arc and Bio-Zeid in addition to chemical fungicide (Rizolex-T as positive control) were evaluated against bean damping-off and root-rot diseases in vitro and in vivo. All tested antagonistic fungal and bacterial bioagents and plant extracts at different concentrations significantly reduced the linear growth of R. solani in vitro and decreased the incidence of R. solani damping-off and root-rot diseases under greenhouse and field conditions. Trichoderma harzianum, T. aureoviride and B. subtilis were the most effective bio-agent, while garlic and onion at 5 and 7% concentration were the most effective plant extracts against damping-off and root-rot diseases meanwhile, B. amyloliquefaciens and neem extract were the lowest effective treatments compared to the control treatment. Under field conditions during the 2019 and 2020 growing seasons, all tested treatments significantly reduced damping-off, root-rot diseases and increased the percentage of survived plants as well as improved bean plant growth parameters (plant height, number of branches/plant), yield and yield components (No. of pods/plant, weight of pods/plant and 100 seed weight) compared to the control treatment. Also, the effects of antagonistic bioagents, plant extracts at 5%, biocides and chemical fungicide on the activity of lytic enzymes (β-1,3-glucanase and protease) and oxidative enzymes (peroxidase and polyphenoloxidase) were determined in the leaves of bean plant.

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