Importance, etiology and management of the tear stain disease symptoms of mango fruits in Ghana

The tear stain symptom refers to slightly raised blisters which reduce the aesthetic value of mango fruits in Ghana. The disease incidence, severity and percentage of exportable mango fruits on infected mango trees were determined in the coastal savannah zone of Ghana in 2019. Samples of disease fruits were collected and the causative agent isolated and identified using phenotypic and genotypic characteristics. Selected copper based fungicides, namely, Cuprous oxide (750 g/kg), Copper oxychloride (500 g/kg) and Mancozeb (800 g/kg) either solely or in combination with Acibenzolar-S-methyl were applied in the field to determine their effect on the disease incidence and severity and on the percentage of exportable fruits. The disease incidence ranged from 9.4% to 11.0% in the major season and 37.3% to 45.0% in the minor season. Severity ranged from 0.08 to 0.1 in the major season and 1.4 to 2.1 in the minor season. The fungus isolated showed the characteristic short conical spores with rounded edges, an indication that it was C. gloeosporioides . The combination of gene sequences of the ITS region and the partial actin gene identified the fungus as C. siamense . All fungicides evaluated were able to reduce the disease incidence and severity on treated trees and resulted in a higher percentage of exportable fruits compared to non-treatment control trees.