Distribution and incidence of Fusarium wilt in oil palm in Benin

Objectives: Fusarium wilt is the first oil palm pathology, who devastates the plantations in Africa. The currents study aims to diagnose the spatial distribution of this pathology and the incidence of the disease caused by Fusarium oxysporum elaeidis (Foe) in the palm oil growing zone of Benin.Methodology and Results: Thus, a survey was carried out in May 2018 covering 16 plantations distributed in four agroecological zones of production of palm oil in Benin. In each plantation, 15 plants were randomly inspected to evaluate the incidence, the severity, and the distribution of the disease. Root and soil samples were collected at the foot of each evaluated tree, at a depth of 20 cm using an auger. Samples were stored in polyetilene bags, for the detection and isolation of the pathogenic agent. The results showed that incidence is significantly different depending on the agroecological zones prospected (p=0.000). Central Cotton Zone (Kétou) and the Fisheries Zone (Adjohoun) recorded an incidence of vascular wilt of 0%, whereas on the sites surveyed in the Depression Zone (Pobè, Adja-Ouèrè) and the Bar Land Zone (Ifangni, Missérété, Sakété, Adjarra) the recorded disease incidences were 30.0% and 12.5%, respectively. This study also revealed an uneven distribution of the pathogen on the sites surveyed. Indeed, the study of the soil samples taken at the foot of the plants revealed that the presence of Foe does not systematically induce the disease, or induces it to varying levels, although the isolate is pathogenic and the material planted on each site is identical.Conclusions and application of results: These results demonstrate a polymorphism of oil palm susceptibility to Fusarium wilt and underline the need to define a new screening approach based on the susceptibility factors of oil palm and which minimizes the intra-crossing variations observed.Keywords: Fusarium oxysporum f. sp. elaeidis, incidence, severity, symptoms oil palms