identification of an effective biocontrol strain suited for commercialization. Twenty rhizobacterial isolates from strawberry rhizosphere were evaluated for its antifungal action against Verticillium dahliae. The selection of best antagonistic bacterial isolate was done by screening for the antifungal action against different soilborne pathogens apart from the target pathogen. In addition it was also tested for the antifungal mechanism of the rhizobacteria for the production of lytic enzymes (chitinases, glucanases and proteases) and plant growth promotion. Collectively all these parameters were combined based on bonitur scale (28 points). The strain that had the highest score was selected for testing its efficacy under greenhouse. Among twenty strains, P. putida E2 had the maximum bonitur scale of 28 points and was highly effective in suppressing Verticillium wilt of strawberry under greenhouse conditions. It was found to perform better than the commercial product Rhizovit (Berg et al., 2001). This clearly explains that selection of bacterial antagonist plays a major role in commercialization of the bacteria for disease management. Initial mistake committed in strain selection will lead to complete failure of the technology.
11.1.3 Pot test and field efficacy
The plant, pathogen and antagonists are co exposed to controlled environmental conditions. Exposure of the host to the heavy inoculum pressure of the pathogen along with the antagonist will provide ecological data on the performance of the antagonist under controlled conditions. Promising antagonists from controlled environment are tested for its efficacy under field conditions along with the standard recommended fungicides. Since the variation in the environment under field condition influence the performance of biocontrol agent, trials on the field efficacy should be conducted for at least 15 – 20 locations under different environmental conditions to promote the best candidate for mass multiplication and formulation development (Jeyarajan and Nakkeeran, 2000).
11.1.4 Mass production and formulation development
The first major concern in commercial production systems involves the achievement of adequate growth of the biocontrol agent. In many cases biomass production of the antagonist is difficult due to the specific requirement of nutritional and environmental conditions for the growth of organism. Mass production is achieved through liquid and semisolid and solid fermentation techniques. The commercial success of biocontrol agents requires
• Economical and viable market demand
• Consistent and broad spectrum action