Problem: Cercospora Spot
This plant disease is caused by a fungus (Pseudocercospora purpurea) that infects avocado leaves and fruit. Old leaf infections are the usual source of spores. In some years, much leaf loss can occur, weakening the tree and slowing fruit development. When the fungus attacks the fruit, the spots often provide convenient entryways for other fungi that rot the fruit.
Spray the tree with a fungicide labeled for cercospora spot, following label directions.