Effect of commonly used host and non-host plants for rotation in control of Ralstonia solanacearum

Ralstonia solanacearum is a soil-borne bacterial pathogen that causes bacterial wilt disease, a major threat to many plants, particularly those in the Solanaceae family, including potatoes, a key food crop in Kenya. Controlling bacterial wilt is highly challenging, as there are no effective curative chemicals (pesticides). Additionally, the pathogen can survive as a latent infection in the soil and the rhizosphere of certain non-host plants, serving as a reservoir for persistent infections and complicating control strategies. For this reason, an investigation was conducted to evaluate the effect of host and non-host plants on the control of R. solanacearum by determining the natural (initial) pathogen population density in the soil using a tetrazolium-based semi-selective medium (SMSA). Potatoes, tomatoes, eggplants, and peppers were used as host plants, while maize, sorghum, cabbage, and beans served as non-host plants. The study assessed R. solanacearum population in the soil, disease incidence, root pathogen attachment, and root invasion using a randomized complete block design (RCBD) with four replications (blocks) and eight treatments. Statistical analysis was performed using GenStat 12.1 (PC/Windows XP), and means were compared using Fisher’s least significant difference (FLSD) test. A significant difference was observed between the wilt incidence of host and non-host plants (P < 0.05). Cabbage was identified as the only safe crop for rotation, as it had a significantly lower R. solanacearum population attached to its roots, in the rhizosphere, or within its vascular bundles (P < 0.05). Maize asymptomatically promoted the persistence of the pathogen within its vascular bundles and accessory tissues. Similarly, beans and sorghum were found to encourage the survival of R. solanacearum in the rhizosphere and as root attachments.