EFFICACY OF MICROBIAL ANTAGONISTS IN NUTRIENT AMMENDED MEDIA FOR THE CONTROL OF BACTERIAL WILT (RALSTONIA SOLANACEARUM) IN TOMATO (SOLANUM LYCOPERSICUM)

Abstract Bacterial wilt, caused by Ralstonia solanacearum, is one of the most important tomato diseases in Kenya. This disease causes yield losses of up to 100%. Biological control agents (BCA’s) such as Bacillus spp and Trichoderma spp are known to be effective against various plant pathogens. Studies were conducted to evaluate the efficacy of microbial isolates of Bacillus subtilis 001, Trichoderma asperellum TR 900 and Metarhizium anisophilae in the control of bacterial wilt. Seedlings were drenched with either B. subtilis 001 , T. asperellum TR 900, Metarhizium anisophilae or a combination of the three biological control agents at concentration 10 7 CFU/g and planted in Ralstonia solanacearum inoculated media at a concentration of 10 8 CFU/g. After six weeks, percent disease incidence was 38.4%, 44.6% and 52.6% respectively compared to 45% in the control. Transplanting of tomato seedlings in nutrient amended media with organic matter, NPK, CAN, later enhanced with B. subtilis, T. asperellum and challenged with Ralstonia solanacearum resulted in significant disease incidence reduction (p<0.001). Therefore, application of Bacillus subtilis and Trichoderma asperellum in amended can provide a potential control of bacterial wilt disease in tomato. Key words: Ralstonia Solanacearum , Bacillus subtilis, Trichoderma asperellum, cfu , BCAs .