The first approach would be to combine several modes of action to either improve efficacy or increase the activity spectrum of the BCAs. This can be achieved by improving the expression of different mechanisms involved in the biocontrol capacities of a BCA. For example, strains of P. fluorescens have been manipulated to produce overproduction of pyrrolnitrin, an antifungal compound (Ligon et al., 2000), or to produce simultaneously phenazine and phloroglucinol, resulting in a greater capacity to suppress Rhizoctonia root rot (Huang et al., 2004). It is also possible to use associations of BCAs having complementary modes of action or targeting different pathogens. The efficiency of Fo47 is usually improved by association with strains of fluorescent pseudomonads, which can be produced in the same substrate as that used to grow Fo47 (Olivain et al., 2004).