-amino butyric acid (-ABA), salicylic acid (SA), calcium oxide (CaO) + urea play important roles in inducing and accumulating phytoalexins in plants. Soil amended with these inducers influenced the presence of Ralstonia solanacearum population density of the soil rhizosphere in both tomato (Lycopersicon esculena cv. ‘Pinto’) and potato (Solanum tuberosum) plants. This led to a reduction both of the percent infection and disease severity compared to the control treatment. Different concentrations of -ABA were effective in reducing the pathogenicity of R. solanacearum to tomato and potato plants as well as decreasing the population of bacteria invading their roots. Different potato cultivars (‘Spunta’, ‘Lady rosetta’, and ‘Nicola’) showed different systemic acquired resistance against the bacteria by application of SA at different concentrations. Also, soil amended with CaO + urea influenced the presence of R. solanacearum population density in the soil rhizosphere of both tomato and potato plants.