Efficacy of bio agents against Aspergillus niger causing collar rot of groundnut in vitro

In vitro studies of fungal and bacterial antagonists, viz., Trichoderma spp., Pseudomonas fluorescens and Bacillus subtillis indicated that T. viride was more effective in inhibiting A. niger. Among the ten different isolates of Trichoderma, Tv- 3 has shown maximum inhibition of 77.7 per cent followed by Tv -18 (75.6%) and T-29 (69.6%). Whereas, T. asperullum was found to be least effective in inhibiting mycelial growth with per cent inhibition of (50.83%). Out of eight different isolates of P. fluorescens, P. fluorescens strain pf-7 showed maximum inhibition of 66.94 per cent followed by P. fluorescence. strain pf-2 (66.23%) and P. fluorescens strain pf-26 (64.46%). Whereas, P. fluorescence strain pf-1 recorded least mycelial inhibition (44.4%). Eight strains of B. subtillis were tested for their antagonistic activity against A. niger. Among them, B. subtillis strain Bs-10 showed maximum inhibition of 64.10 per cent followed by B. subtillis strains Bs-29 and Bs-9 (61.46%). Whereas, B. subtillis strain Bs-4 was found to be least effective in inhibiting mycelila growth (45.36%).