Sweet orange scab is caused by the fungus Elsinoe australis. The fungus is spread by water, generally by splashing, wind-driven rain or overhead irrigation. Three to four hours of wet conditions can result in disease.

How do you treat citrus scabs?

Treating citrus scab disease is best accomplished with the use of fungicides and well-timed sprays. The first treatment should be applied before bloom. Some proven to be effective treatments include a spray when blooms are partially open, about 25% of blooms.

What is sweet orange scab?

Sweet orange scab (SOS) is a plant disease caused by the fungal pathogen Elsinöe australis, which results in the formation of pustules (small raised spots or rounded swelling) and lesions on the skin or rind of citrus fruit.