09-08-2013, 03:16 PM
Evaluation of antagonists and antibiotics against bacterial wilt of brinjal caused by Ralstonia solanacearum.
ABSTRACT
Brinjal crop suffers from many biotic stresses, out of which soil borne diseases are of great economic importance. The bacterium (Ralstonia solanacearum) responsible for wilt in brinjal survives in the soil and maintains its infectious population over several years (Hartman and Datnoff, 1997). Managing soil borne diseases is quite difficult by depending upon chemical measures alone, hence, it is essential to explore other methods and also to have integrated approach for the management of such diseases. In this direction management of plant pathogens using biocontrol agents, have assumed significance and has become quite popular in managing soil-borne diseases. In the present investigations, attempt was made to identify the effective biocontrol agents and antibiotics against Ralstonia solanacearum found associated with brinjal crop. Out of 16 biocontrol agents tested, the bacterial antagonists, Pf1 and Pf2 isolates of Pseudomonas fluorescens were more effective than the fungal antagonists against R. Solanacearum and both were statistically at par with each other. Among the fungal isolates, T. viride (Tv4) was the most effective against R. solanacearum and it was statistically at par with isolate Th4 and Tv1. It was observed that the isolates of Chaetomium globosum, Cg1 and Cg2, were least effective against the test pathogen. Out of 10 antibiotics tested, Plantomycin (streptomycin sulphate + tetracycline) was most effective antibiotic, resulted in mean inhibition zone followed by pencillin at 500 ppm concentration. The least effective antibiotics tested were azithromycin, erthromycin and ampicillin which did not show any inhibition zone at any of the tested concentrations.