Alternaria mali Roberts
Distribution: An increasing problem in the eastern North America, but has yet to be found north of Virginia.
Damage can be confused with injury from the fungicide Captan (shown here).
Mid-Atlantic Orchard Monitoring Guide
The disease primarily affects the foliage, causing circular, necrotic lesions with a light brown interior (A) that later become surrounded by a darker purplish halo (B). Defoliation can occur by late summer on susceptible varieties that are heavily infected (C). The pathogen can also attack green, woody tissue, but it rarely attacks the fruit.