In vitro Assessment of Bio-agents and their Culture Filtrate for Sustainable Management of Rhizoctonia solani

Rice is a vital cereal crop that forms the staple diet for more than half of the global population. It plays a critical role in food security and nutrition, particularly in Asia, where countries such as China, India, Indonesia and Bangladesh lead the way in cultivation and consumption but severely affected by Rhizoctonia solani causing heavy yield loss. This study investigated the in vitro efficacy of several bio-agents and their culture filtrates in suppressing the mycelial growth of Rhizoctonia solani. In the first experiment, direct applications of Trichoderma viride, Trichoderma harzianum, Pseudomonas fluorescens and Bacillus subtilis significantly reduced fungal radial growth, with T. harzianum (68.37% inhibition) and T. viride (59.18% inhibition) showing the most potent antagonistic activity compared to the untreated control. In the second experiment, culture filtrates from various bio-agents (Trichoderma viride, Trichoderma harzianum, Pseudomonas fluorescens and Bacillus subtilis) were evaluated. Results revealed that T4 and T9 produced the highest percent inhibition on the seventh day (82.95% and 78.18%, respectively), while other treatments showed moderate to low efficacy (13.37–59.45% inhibition). Statistical analysis (CD and SE) confirmed the significance of these differences among treatments in both experiments. The collective results indicate that both living bio-agents and their culture filtrates, particularly those derived from effective strains such as Trichoderma spp., offer strong potential for the biological control of R. solani, contributing to sustainable plant disease management strategies.