Alternaria mali Roberts
Distribution: An increasing problem in the eastern North America, but has yet to be found north of Virginia.
Circular, necrotic lesions on leaves have a light brown interior.
Turner Sutton, NC State Univ.
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.