Abstract

Management of tomato early blight pathogen (Alternaria solani) has relied principally on application of synthetic fungicides. The use of biological control agents has been recognized as a viable option to synthetic chemicals in plant disease control. The present study evaluated the effects of Pseudomonas fluorescens, P. aeruginosa, P. putida, and P. cepacia on tomato early blight pathogen and investigated their efficacy on the yield components and yield of tomato plants infected with A. solani. Tomato seeds raised in the nursery beds were transplanted to the main field after three weeks. The experiment was laid in a randomized complete block. Treatment application was done by immersion of roots of three-week-old seedlings of tomato in Pseudomonas solution prior to transplanting. The treatments consisted of plots treated with P. fluorescens, P. aeruginosa, P. putida, P. cepacia and the control. Data were collected on disease severity, plant height, stem girth, number of fruits per plant, fruit length and fruit weight. Tomato plants in the control plot had significantly (p<0.05) higher disease severity (52.0) There was no significant difference in the severities of early blight on tomato plants treated with P. fluorescens, P. putida and P. cepacia. Tomato plants treated with P. aeruginosa had significantly (p<0.05) higher height (39.0 cm) than all other treatments. There was no significance difference in the fruit weights of tomato plants treated with P. fluorescens, P. aeruginosa, P. putida, and P. cepacia. Tomato plants in the control plots had a significantly lower fruit weight (69.5 g). Findings of the present study demonstrated a promising approach of biological control of early blight pathogen with Pseudomonas species.  Results of this work could be used as bedrock for formulation of an effective and eco-friendly strategy for the management of early blight disease.

Key words: Tomato, Alternaria solani, Pseudomonas, biological control, early blight.