Study of Antagonistic Beneficial Microorganisms to Phytophtora colocasiae, Causal Agent of Taro Mildew ( Colocasia esculenta (L.) Schott)

The cultivation of taro is of great economic and social importance on a global scale. The current orientation towards agricultural production and the serious consequences of the mildew of taro to crops prompts to find alternatives to chemical control. This study aims at selecting in the taro habitat (leaves, rhizosphere) the microorganisms with high antagonistic potential capable of ensuring the biological control of P. colocasiae. Fungus isolated from the taro-infected leaves of the cultivar "Macumba or Ibo coco" from the V8-Agar medium, was kept in pure culture. The different antagonists were obtained by two trapping techniques using P. colocasiae as bait for the associated microorganisms and by the decimal dilution technique. The results reveal fourteen antagonist isolates, including five fungi and two bacteria isolated from the leaves; Against 4 bacteria and 3 fungi at ground level. Identification of the latter identified the presence of Penicillium Sp, Trichoderma Sp, Aspergillus Sp, Pythium Sp., Bacillus Sp, Rhizobium, Streptomyces and seven other unidentified isolates (Ni). The different in vitro tests showed that Rhizobium and Ni4 showed the strongest inhibitions (91.66 and 90.69%). The greenhouse tests showed the high-inhibitory effect of Trichoderma Sp. and Rhizobium, which showed very low foliar alteration percentages (9.65 and 1.86%). These antagonists would be of particular benefit to farmers in the development of biological pesticides.