Current Situation of Mango Bacterial Black Spot Caused by Xanthomonas campestris pv mangiferaeindicae in the Poro and Tchologo Regions in Côte d'Ivoire

Abstract

Mango bacterial black spot is an emerging disease in Côte d'Ivoire and the damage caused is becoming more and more significant. This study aims at diagnosing bacterial black spot incidence and severity level in regions of intensive mango production. Surveys were carried out during the vegetative stage of mango trees from July to August 2019 and the fruiting stage from March to April 2020 in 50 orchards in the Poro and Tchologo regions. In each orchard, 5 mango trees regularly dispersed over an area of 0.5 ha were assessed. On each tree, three (3) twigs per cardinal point were selected then the leaves counted and the leaf area covered by bacterial black spot symptoms determined. At fruiting stage, bacterial black spot severity on 40 fruits per selected tree, at the rate of 10 fruits per cardinal point was assessed. Bacterial black spot symptoms were observed in all orchards and the bacterium, Xanthomonas campestris pv. Mangiferaeindicae, was systematically isolated basing on symptoms taken from the leaves and fruits collected. Statistical analysis of the mean incidence and severity per town revealed a variability of 83.2% up to 90% on the leaves and 41.42% up to 55% on the fruits regarding incidence. As for severity, the highest values, 10.58% and 5.23% on leaves and fruits respectively were recorded in the department of Tafiéré. Mango bacterial black spot is found in orchards located in the Poro and Tchologo regions. Incidence and severity are strongly related to the humidity conditions of the production area.