Biological control of damping off (Pythium aphanidermatum) using Streptomyces lavendulae isolate 21 on tobacco seedbeds

Soil actinomycetes, particularly Streptomyces spp., possess antagonistic activity against a wide range of plant pathogens as they are potent producers of antibiotics. In the present study 40 isolates of actinomycetes were isolated from tobacco soils of India and screened against Pythium aphanidermatum in vitro. Among them, ten Streptomyces isolates showed high antagonistic activity. Streptomyces lavendulae isolate 21 showed strong inhibition zone (24mm) of the pathogen. Experiments in vivo using spray of mixed spore suspension of P. aphanidermatum and S. lavendulae isolate 21 on tobacco seedbeds resulted in marked reduction of disease severity, significant improvement in dry weight, leaf area and nutrient content. The treatment P. aphanidermatum S. lavendulae recorded 32 per cent increase in number of transplantable seedlings against P. aphanidermatum alone, while the treatment Streptomyces alone recorded 1.87 times increase in number of transplantable seedlings against control.