Abstract: A study was carried out to establish on one hand, the genetic diversity of the populations of Pyricularia oryzea at Abomey Calavi and the other, to find out the favorable culture media for mass production of the conidia and the mycelium of P. oryzea for the laboratory techniques. Thus, trapping virulence races present in the prospected ecosystem in Abomey-Calavi helped to highlight the fact that the resistance genes: Piz-t, Piks, Pik-p, Pi1, Pi5 (t), Pi7, Pia, Pish and Pik were overcome by a large section of the pathogen population. Virulence genes that are capable of overcoming resistant genes Pii, Pi9, Pi33, Pi5 (t) Pi7 and Pikm are however absent or rare. The latter represented the genes that were effective against the pathogen population studied. On the other hand, this study showed that Pi5 and Pi7 gene association, which is individually ineffective, has conferred a durable blast resistance observed in Moroberekan. Four operational conditions were selected on the basis of the spores quantities produced and the fastness of the mycelium growth. The addition of starch in the medium does not influence the fungus mycelium growth. But this growth is clearly influenced by extract doses of yeast. The best sporulation is obtained for culture media consisting of 20 g of starch and 2 g of yeast extract, 10 g of starch and 2 g of yeast extract L-1.