Selection of biocontrol agents for the management of white rot of peas caused by Sclerotinia sclerotiorum

Nine isolates of Trichoderma spp., four of Coniothyrium minitans, thirty of fluorescent pseudomonads and ten of Bacillus subtilis were tested for their bio-efficiency against Sclerotinia sclerotiorum following dual culture and Poisoned food techniques. Three isolates of T. atroviride (T1, T2 and T38) were graded as R1 in dual culture and their culture filtrate completely inhibited the colony growth and sclerotia formation of S. sclerotiorum. Two isolates of C. minitans (CmCo and Cm20) showed mycoparasitism in dual culture and inhibited pathogen colony growth up to 79.22 and 77.0 per cent, respectively at 50 per cent culture filtrate concentration. Fp6 isolate of Pseudomonas putida biotype B and Bs1 isolate of B. subtilis exhibited antibiosis in dual culture and inhibited colony growth up to 50.67 and 67.71 per cent, respectively at 50 per cent culture filtrate concentration. Isolates of bioagents found effective through dual culture and poisoned food technique were further evaluated for degradation of sclerotia of the pathogen. T1 and CmCo isolates of T. atroviride and C. minitans showed better efficacy in reducing the viability of sclerotia of the pathogen than other isolates of bioagents. Sclerotia produced in field were more prone to degradation than laboratory produced ones. In field, all these antagonists reduced the disease incidence but fungal antagonists showed better biocontrol potentiality as compared to bacterial antagonists.