Piriformospora indica Suppresses Natural Incidence and Severity of Black Leaf Mold of Tomato Incited by Pseudocercospora fuligena Over Strobilurin and Triazole Fungicides with Enhanced Growth and Yield

Abstract

Aim: To study the effect of Piriformospora indica-root colonisation and spraying of azoxystrobin, pyraclostrobin (strobilurins), propiconazole and tebuconazole (triazoles) fungicides for the management of black leaf mold of tomato. Study Design: Completely randomized design for lab; Randomized block design for field studies. Place and Duration of Study:  College of Agriculture (Kerala Agricultural University), Vellayani and Coconut Reserarch Station, Balaramapuram, Thiruvananthapuram during 2022-2024. Methodology: In vitro evaluation of strobilurin and triazole fungicides against Pseudocercospora fuligena was done by poisoned food technique. Field evaluation of P. indica-colonized plants var. Vellayani Vijai was performed to assess the incidence and severity of black leaf mold of tomato over systemic fungicides. Results: The strobilurin fungicides partially and the triazoles completely inhibited the mycelial growth of the pathogen. P. fuligena was completely inhibited at 100 ppm of triazole fungicides, but at least 25 per cent growth was observed in strobilurin fungicides even at 1000 ppm. P. indica significantly reduced the natural incidence and severity of black leaf mold disease at 45 DAT and it extended to the entire crop period in the field condition. The disease incidence was 15.00 per cent in the P. indica-colonised plants; whereas it ranged from 28.12 to 31.85 per cent in the systemic fungicides sprayed plants; and in control plants, it was significantly high with 47.50 per cent. Similarly, the disease severity was least (PDI: 7.99) in the P. indica-colonised plants at 45 DAT.  But the disease severity in the fungicides alone sprayed plants were 15.89 to 18.96; whereas in control plants, the severity was 40.83. Moreover, P. indica enhanced plant height, early flowering, fruit setting, flowers, fruits and average yield over control and systemic fungicides sprayed plants. Conclusion: P. indica confers tolerance to black leaf mold disease over the strobilurin and triazole fungicides apart from the enhanced crop yield.