Greetings, Does anyone know what causes pimples on the skin of mango fruit? It seems to be a local problem in the Lesser Antilles (Caribbean). Some think the symptom is caused by spider-mites (Eryophyes sp.), but sofar I have never been able to find these here on leaves, flowers or fruit in relation to this symptom. Neither could I trace any particular fungus hyphae or spores on these with help of a microscope. Nothing under the skin layer looks abnormal (plant cells under the skin look normal and even the skin itself looks normal). The fruit will not ripen in a normal way though, and aborts most of the time when mature. The stone (seed) develops in a normal way, and may even germinate sometimes after planting. Most fruits on trees with these symptoms develope normally Some people suggested it may be a result of watering with septic-tank water, but I have observed these symptoms as well on abandoned plantations where never was a waste water system in operation.
I don't know the answer, but a few resources: Pests and Diseases of Mangifera indica via Purdue's Center for New Crops Mango Fruit Facts from California Rare Fruit Growers Diseases of Mango from the American Phytopathological Society