Evaluation of different native Streptomyces spp. for effective management of rhizome rot of turmeric

The efficacy of talc based bioformulations containing various biocontrol agents against rhizome rot disease caused by Pythium aphanidermatum in turmeric plants was evaluated under field condition. Indigenous biocontrol agents such as Streptomyces lydicus, Streptomyces griseus and Streptomyces sannanensis belonging to actinomycetes group, Pseudomonas fluorescens (bacterial) and Trichoderma atroviride (fungal) were selected for the biological control of rhizome rot of turmeric. The results indicated a significantly stronger reduction in disease severity in trial plots treated with Bacillus subtilis based commercial fungicide 'Companion' when compared to plants treated with indigenous biocontrol agents. However, it was reverse in trial plots in terms of turmeric rhizome yield potential, yield attributes, physiological components, biochemical constituents and quality characteristics of rhizomes. Among 17 treatments, a dual mixture of S. griseus and T. atroviride achieved the best disease control as well as plant growth improvement when compared to single and triple combinations of biocontrol agents. The present study confirms that exploration of microbial formulations containing Streptomyces spp. as soil inoculant to turmeric plants exhibited some benefits to turmeric plant growth as well as controlling rhizome rot disease, which ultimately enhance the overall quality characteristics of rhizomes. Further, our results suggest that a dual combination of biocontrol agents represent a promising method for effective management of rhizome rot of turmeric.