Evaluation of the Epidemiological Factors Responsible for the Appearance of Phytophthora Palmivora and Phytophthora Megakarya, Causal Agent of Black Pods Disease in the Department of Méagui, Southwestern Côte D'ivoire

Author(s): Franck Zokou Oro, Hermann-Désiré N'Guessan Maximilen Lallié, Guy Kouassi Brou, Alain Deron Koffi, Laurence Blondin, Claire Neema, Christian Cilas, Hortense Atta Diallo

The cocoa black pod disease is caused by a fungus Phytophthora sp, which comprises two main species (Phytophthora palmivora and Phytophthora megakarya) commonly found in Ivorian cocoa plots and which cause significant damage. Despite numerous studies, this disease continues to spread and even more so Phytophthora megakarya, which did not exist in Côte d'Ivoire, is beginning to spread significantly. This study focused on the evaluation of the epidemiological factors responsible for the progression of Phytophthora megakarya and Phytophthora palmivora in the Department of Méagui, southwestern Cote d'Ivoire. To this end, a prospective survey was conducted in three cocoa plots in Méagui, which collected epidemiological data on "Foliar coverage rate", "Maintenance level" and the prevalence of black pod. Molecular data on black pod disease isolates were extracted from immature pods with black pods symptoms. A descriptive analysis was first applied to the data to understand their dispersion, followed by a comparative analysis (student's t-test) to evaluate the relationship between epidemiological parameters and disease prevalence. Finally, a molecular analysis in the laboratory made it possible to characterize the different species of Phytophthora sp. The results of the molecular analysis showed the presence of Phytophthora megakarya at 79% against 21% for Phytophthora palmivora. The results of the student t-test showed that this prevalence of black pod is related to the lack of plot maintenance (P=0.036˂0.05) and high leaf coverage of cocoa trees (P=0.003˂0.05). However, distribution maps of the different species show that Phytophthora megakarya is the most dominant species on the Méagui site.

Cocoa, Maintenance Level, Foliar Coverage, Phytophthora sp.

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