Vegetos

Abstract

Antagonistic activities of seven bio-agents i.e. Pseudomonas fluorescence, Pseudomonas sp., Aspergillus flavus, A. niger, Penicillium sp., Trichoderma virens and T. harzanium against three potato pathogens viz. Rhizoctonia solani, Fusarium sp. and Phytophthora infestans were studied in vitro. Result revealed that both volatile and non-volatile substances released by bio-agents significantly inhibited the growth of these pathogens. Temperature range of 25–30°C and pH range of 6.0–8.0 were found optimum for Trichoderma spp. while bacterial bioagents grew optimally at 30°C and pH 7.0. There was no detrimental effect of fungicides: cymoxanil based (3000 ppm), metalaxyl based (2500 ppm) and mancozeb (2000 ppm) on the growth of T. virens and T. harzianum while growth of Penicillium sp., Pseudomonas sp. and P. fluorescence was inhibited completely. At reduced dose, cymoxanil + mancozeb (1500 ppm) showed highest inhibition of Pseudomonas sp (61.94%) while P. fluorescence exhibited lowest inhibition (46.13%). Highest inhibition was found with cymoxanil based fungicides for both bacterial and fungal bioagents while lowest inhibition with mancozeb in fungal bioagents and with metalaxyl based fungicides in bacterial bioagents.