Answer: Sounds like Phytophthora, or brown rot. This is a fungal disease and the spores of the pathogen are water splashed from the soil onto the tree. From there it can travel to other parts of the tree as well as to other trees. The only management option for brown rot of citrus is prevention. Apply a copper fungicide, preferably Bordeaux, in October or November, when the rainy season begins. Spraying the ground underneath the trees can reduce brown rot infections, as well. For more information, contact your local Cooperative Extension office at (209) 385-7403.
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