Plant products to control Ralstonia solanacearum causing bacterial wilt in tomatoes (Solanum lycopersicum) in Kenya

Sammanfattning: Plant pathogens are a significant contributor to yield losses around the globe. The plant pathogen Ralstonia solanacearum causes bacterial wilt, often resulting in yield loss in numerous vital crops such as tomatoes. In Kenya, this disease harms the income of the individual smallholder farmer, and to an extent might threaten this east African nation’s food security. This study aimed to evaluate the effectiveness of using locally sourced plant products from Lantana camara (common lantana), Allium sativum (garlic), Azadirachta indica (Neem) and Solanum incanum (sodom apple) in the management of bacterial wilt in tomatoes (Solanum lycopersicum) in Kenya. The study was divided into two parts. In part one, the plant extracts were examined in a disc diffusion test to determine if plant extracts had an inhibitory effect on the growth of R. solanacearum in vitro. The second part was a greenhouse experiment conducted with tomato seedlings, where pulverised plant material to the soil substrate were added. The effectiveness of disease suppression of the different plant products was assessed using the AUDPC value (Area Under the Disease Progression Curve). No inhibitory effects from the plant extracts on the growth of R. solanacearum were observed in the in vitro experiment. The greenhouse experiment showed no significant difference between the treatments, which means that we cannot conclude that the species L. camara, A. sativum, A. indica and S. incanum have an inhibitory effect on the in vitro growth nor on the rate of disease progression of R. solanacearum in tomato. These experiments should be regarded as a pilot study. A more detailed analysis of the subject would be needed in order to draw a more reliable conclusion since this experiment encountered some setbacks.