Citrus Greasy Spot on Grapefruit: Copper Fungicide Timing

White Fungus on Unripe Citrus Fruit

Tangelo and grapefruit trees in Southern California show white fungus on fruit tops, fruit dying, ants on infected fruit, and dieback with dry brittle branches. Spreading to orange tree.

Diagnosis: Greasy Spot

Fungal disease controlled effectively with copper fungicides or oil sprays. Critical: spray underside of leaves.

Application Timing

• Single application in June or July.
• Fungus grows superficially for 2–3 weeks before penetrating leaf.
• One spray protects new growth and kills existing surface fungus.

Why This Works

Unlike most fungal diseases, you don't need to spray before spores land; the long penetration window allows curative action.