Hawthorne leaf blight, also called leaf spot, is caused by a fungus and exacerbated by cool, wet weather. Infection manifests as small reddish-brown spots; then the area between spots will yellow and leaves will eventually fall off. If canopy loss occurs several years in a row it can severely weaken the tree.
English hawthorne and Paul’s scarlet hawthorne
Prompt removal of leaves with symptoms, raking and destroying fall foliage, and foliar fungicide treatment in the spring.