Role of plant growth promoting microbes in the control of fungal foliar diseases of tomato under protected cultivation

Background This study was conducted to assess the effectiveness of plant growth-promoting microbes on the foliar disease of organic tomatoes under protected cultivation. The biological control agents, viz., Trichoderma harzianum (T. harzianum), Bacillus subtilis (B. subtilis), and Pseudomonas fluorescens (P. fluorescens), used seed treatment, seedling dip, and spray separately in sequence with the plot size of (2.5 x 1 m) and the spacing of (45 x 60 cm). The observations on percentage disease yield and plant growth parameters were assessed, and economics was calculated. Tukey's HSD at p < 0.05 was used to compare all means among treatments. Results The results showed that seed treatment with B. subtilis at 5 g, followed by a seedling dip with B. subtilis at 10 g l(-1) and spray with B. subtilis at 5 g l(-1) four times at 15 days intervals significantly (p < 0.05) reduced the tomato diseases early blight, septoria leaf spot, and powdery mildew (T2). These results were comparable to seed treated with P. fluorescens at 5 g l(-1), followed by a seedling dipping with P. fluorescens at 10 g l(-1) and spraying with P. fluorescens at 10 g l(-1) four times at 15-day intervals (T3). Except for T1, plant parameters, yields, net returns, and benefits were significantly higher (p < 0.05) than the untreated control (T8). Conclusion The applications of B. subtilis and P. fluorescens as plant growth-promoting microbes had a considerable scope for managing fungal foliar (multiple) diseases and achieving sustainable yields under the protected cultivation of organically grown tomatoes.