Final report : biocontrol of bean ashy stem blight by improved rhizobium biotechnology

In the Dominican Republic, the disease was detected only in the San Juan de la Maguana province. Two fungal isolates from there were characterized and compared to one isolate from Isabela, Puerto Rico. A collection of 35 Rhizobium phaseoli strains were obtained and tested for fungal inhibition. Neither these nor other strains from the collection were capable of inhibiting the fungal pathogen sufficiently to be considered potential biocontrol agents. However, other bacterial genera (Pseudomonas and Bacillus) produced strong in vitro inhibition in a new media compatible with both bacterial and fungal growth. In vivo screening highlighted the potential of some strains as plant growth promoting rhizobacteria (PGPR) inoculum. Greenhouse experiments demonstrated the value of P. cepacia strain UPR 5C as a biofungicide against M. phaseolina. Personnel from Colombia and the Dominican Republic, in particular, received training and in some cases M.S. degrees while working for the project. Although the results obtained during the project indicate the potential of some bacterial strains as biofungicidal agents, further research is needed before the present technology could be commercially applied.