Efficacy of slow sand filtration enriched with Trichoderma atroviride in the control of Rhizoctonia solani in soilless culture

Soilless cultivation is increasingly common, but the nutrient-rich drainage from substrate cultivation is often discarded. However, drainage can be safely reused if previously disinfected. Slow sand filtration (SSF) is a low-cost, ecological, and effective method for water disinfection, primarily through biological control. Enhancing SSF with antagonistic microorganisms is not well-studied. Additionally, SSF has not been tested to control Rhizoctonia solani, a phytopathogen that can be spread by irrigation water. Therefore, the objective of his work was to test the efficacy of a slow sand filter improved through the inoculation of the antagonistic fungus Trichoderma atroviride, evaluating its suppression capacity against Rhizoctonia solani spread by the irrigation water in a closed substrate cultivation of cucumber (Cucumis sativus). Five experiments were conducted, testing the presence and absence of a sand filter, T. atroviride, and R. solani in each trial. Median disease severity was expressed on a scale of 1–5. The improved SSF increased disease control percentage by 49% compared to SSF alone and by 86% compared to no disease control method. In some experiments, SSF with T. atroviride totally controlled R. solani. The results confirm that biologically enhanced SSF with T. atroviride can effectively disinfect drainage in closed soilless cultivation systems infected with R. solani.