MANAGEMENT OF ALTERNARIA LEAF SPOT ON INDIAN MUSTARD THROUGH CHEMICAL AND BIOLOGICAL AGENTS

Experiments were conducted under in vitro and field conditions to evaluate some commonly known Chemical fungicides viz., Azoxystrobin 23% SC (Amistar), Propiconazole 25% EC (Tilt), Mancozeb 75% (Indofil M-45) and combined formulation of Carbendazim 12% + Mancozeb 63% (Colt) and antagonistic strains of Bio-control agents viz., Trichoderma harzianum, Trichoderma viride and Pseudomonas flourescens against Alternaria brassicae causing Alternaria leaf spot on Indian Mustard (Brassica juncea) using Bioassay and Dual culture technique respectively. Trichoderma harzianum was recorded to be the most effective among the bio agents under lab conditions, inhibiting up to 65.83% of the test pathogen. Tilt proved best in lab conditions, showing complete inhibition of the test pathogen at all concentrations and attaining the lowest ED50 value of 6.13 and ED90 value of 55.27 µg/ml. Amistar gave best performance among all test chemical fungicides under field conditions with lowest severity of 36.30%, showing lowest AUDPC of 458.33 and an infection rate 0.0266 unit-days and T. harzianum best among the bio agents with record severity of 68.88% with AUDPC of 750.00 and infection rate 0.0437 unit-days. All the treatments improved the growth and yield of the crop significantly, with highest yield being recorded in treatment of Amistar (2536.21 kg/ha) followed by T. harzianum (2212.15 kg/ha). New generation fungicides like Azoxystrobin and Propiconazole proves to be highly efficient in controlling foliar pathogen like Alternaria as compared to conventional pesticides available in the market, yet the growing concern in the use of chemicals in crop protection is rising among the consumers, therefore it is high time to focus on exploring certain non-pathogenic Bio-control strains and improving it to fight off infectious foliar infecting pathogens in phyllosphere and foliar regions of plants.