Control of root rot diseases of tomato plants caused by Fusarium solani, Rhizoctonia solani and Sclerotium rolfsii using different chemical plant resistance inducers

Root rots of tomato plants caused by Rhizoctonia solani, Fusarium solani and Sclerotium rolfsii are serious diseases leading to delayed growth and subsequent death of severely infected plants. Effect of some chemical inducers such as potassium salts, salicylic acid and sorbic acid on control of root rot pathogens and their impact on growth, quantity and quality parameters of tomato cv. Super Strain B were investigated. All the tested chemical inducers significantly reduced severity of root rots under greenhouse and field conditions. Potassium salts based-treatments, followed by salicylic acid, were the most effective in decreasing incidence of root rots induced by all tested pathogens. However, sorbic acid was found to be the least effective treatment. In field trials, the highest reductions of root rot incidence and disease severity were recorded on tomato plants treated with potassium sorbate used at 7.5% and dipotassium hydrogen phosphate (K2HPO4 ) 400 mM followed by salicylic acid 100 mM treatment. Disease incidence and severity were reduced by 65.4 and 62.5% in 2012, and by 63.2 and 53.8% in 2013 cropping seasons, respectively. Application of potassium salts followed by salicylic acid was the most efficient for the increase of growth parameters, yield and quality of tomato fruits while compared to control. Therefore, it could be suggested that application of plant chemical resistance inducers could be commercially used for controlling tomato root rot diseases and increasing both quality and quantity of tomato since they are safe, less expensive and effective against these diseases even under field conditions.