Variation occurs between cultivars and between growth flushes, with the most infection occurring on the earliest flush of growth, and little or none on the last flush of growth in late summer. Septoria leaf spot. Most commercial blueberry plantings in eastern North Carolina are affected with Gloeosporium leaf spot which can cause severe defoliation and reduction in yield. This disease can produce flecking, leaf anthracnose and stem lesions. Gloeosporium leaf spot was first described as a stem and leaf fleck disease of blueberry.
Symptoms first appear as small reddish flecks on young leaves and stems of succulent shoots.
Leaf and stem flecks do not develop further. Development of lesions results primarily from infection through hydathodes at the margins of the leaf, and to a lesser extent through wounds. Secondary stem lesions can develop from leaf infections by growing through the petiole into the stem, and from bud infections late in the season. Stem lesions first appear on current season's growth as dark red circular to elliptical lesions around leaf scars. As the lesions enlarge, the affected stems turn brown and eventually become gray and die.