Just like any other plant, mangoes are affected by diseases and these include:
Anthracnose (Colletotrichum gloeosporioides)
Afflicts mangoes most severely. In the case of anthracnose, mango disease symptoms appear as black, sunken, irregularly shaped lesions that grow resulting in blossom blight, leaf spotting, fruit staining and eventual rot. The disease is fostered by rainy conditions and heavy dews.
Mango scab (Elsinoe mangiferae) is another fungal disease that attacks leaves, flowers, fruit and twigs. The first signs of infection mimic the symptoms of anthracnose. Fruit lesions will be covered with a corky, brown tissue and leaves become distorted.
Verticillium wilt attacks the tree’s roots and vascular system, preventing the tree from up-taking water. Leaves begin to wilt, brown, and desiccate; stems and limbs die back; and the vascular tissues turn brown. The disease is most damaging to young trees and may even kill them.
Parasitic algal spot is another infection that more rarely afflicts mango trees. In this case, mango disease symptoms present as circular greenish/grey spots that turn rust red on the leaves. Infection of stems can lead to bark cankers and stem thickening and death.
Treating a sick mangoes for fungal diseases involves using a fungicide. All susceptible parts of the tree should be thoroughly coated with the fungicide before infection occurs. If applied when the tree is already infected, the fungicide will have no effect. Fungicide sprays need to be reapplied on new growth. Apply fungicide in the early spring and again 10-21 days later to protect the panicles of blossoms during development and fruit set. If powdery mildew is in evidence, apply sulfur to prevent the spread of the infection to new growth.
If the tree becomes infected with verticillium wilt, prune out any infected limbs.
Mango scab generally doesn’t need to be treated since an anthracnose spray program also controls scab.
Algal spot will also usually not be an issue when copper fungicides are periodically applied during the summer. To reduce the risk of fungal infections, grow only anthracnose resistant cultivars of mango. Maintain a consistent and timely program for fungal application and thoroughly cover all susceptible parts of the tree.