What is the cause of black spots on the leaves of mango trees?
Anthracnose infection. Black spots appear on both young and old leaves, bloom, and fruit. On the leaves, the black spots go all the way through the tissue. On young leaves, the black spots appear along the margins causing leaf curl and leaf drop. The disease causes flowers to drop. After the flowers have fallen, the bare bloom spikes have a darkened, dirty appearance. Young fruit will become deformed and split, eventually dropping. Applications of copper fungicides as new tissue develops and protecting the expanding tissue will prevent anthracnose infections. For infections that come following nutritional deficiencies or wounds, prevention is the only successful control. Prevention involves spraying weekly from the first appearance of the flowers until all fruit have set with copper fungicide sprays (always follow label directions). To prevent fruit infections, sprays must be applied from the time the fruit sets until mid-May to mid-June depending on variety. See Common Diseases of Man
