The Aetiology, Incidence and Severity of Mango Tree Decline Disease in Ghana

Abstract

Mango tree decline was previously an unknown disease in Ghana. In this study, mango trees from all the major agro-ecological zones of Ghana, where mangoes are grown were surveyed for the disease incidence, severity and aetiology of a similar disease affecting the crop. Farm visits were made to some selected farms within the selected agro-ecological zones and both the local and exotic trees were inspected. The percentage of infected trees were calculated while the severity of the disease was rated on a scale of 0-5, where 0 = no symptoms and 5 = death of trees. Samples of the diseased plant parts were collected and the causal agent was isolated on media and identified. The isolated fungus was tested for its pathogenicity using mango seedlings as test crops. The disease, characterised by profuse gumming, bark cracking and die back, was found to be present in all the agro-ecological zones. The disease incidence was higher on the local variety compared to the exotic varieties. Lasiodiplodia theobromae, isolated from the diseased plant parts, was able to cause the disease on inoculated mango seedlings. The nature of the disease symptoms and its causative agent in Ghana, confirms the disease as the mango tree decline disease.