Sooty Mold
Sooty mold is a dark fungal coating that grows on sticky honeydew deposited by certain sap-feeding insects. On mangoes it can cover leaves, twigs, or peel without being the same disease as anthracnose. Heavy coverage can reduce light reaching leaves and make fruit unattractive. Inspect for scale insects, mealybugs, or other honeydew producers and consider ant activity. Managing the source of honeydew is generally more useful than repeatedly trying to remove the black coating without addressing the insects.