Effect of the Hydric Factor and Arbuscular Mycorrhizal Fungi (AMF) on the Severity of Phytophthora colocasiae

Colocasia esculenta (L.) Schott is an important food for millions of people in countries of Africa, Asia and Central America. The cultivation of taro suffers from an epidemic disease, the taro mildew, caused by P. colocasiae, which is a disease that manifests itself as oily and circular spots on tubers, stems, petioles and on taro leaves causing losses of more than 50% in less than ten days. This study was carried out to evaluate the impact of this pathogen on the leaf area parameter in two varieties of taro (Ibo coco and Atangana) at different water levels, then evaluate the incidence of the disease severity on the leaves at different water levels and study the behavior of this pathogen on plants previously inoculated with arbuscular mycorrhizal fungi (AMF) of the genus Gigaspora magarrita and Acaullospora tuberculata. The plants were separated into three batches (control batch not infected, batch infected with pathogen and batch not only infected but also inoculated with AMF at different water contents (500 ml, 370 ml, 250 ml and 125 ml), the batch infected with the pathogen alone showed a reduction in the growth parameters compared to the control, and the inoculated and infected batch also showed a reduction in growth parameters but closer to the control. In addition, the speed of propagation of the lesion in the inoculated batch is reduced compared to that of the uninoculated batch, and this speed also decreases with the water content, as a result of which the mildew of taro develops easily. Moreover, the addition of AMF makes it possible to minimize its propagation.