Apple Scab - Crabapple Scab Disease

Apple scab is a fungal disease most common in areas of relatively high rainfall and relative humidity. However, scab outbreaks such as those that occurred in the early 1980's indicate that persons associated with the central Washington apple industry must constantly be alert to conditions that are conducive to the development of this disease, even in arid climates such as central Washington. If uncontrolled, the fungus may defoliate trees and blemish fruit to a point where it is unmarketable. In central Washington, the disease is particularly troublesome under overtree irrigation.

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