Blueberry Facts

Leaf spot diseases
Septoria albopunctata, Gloeosporium minus, Gloeocercospora inconspicua (fungi)
Annemiek Schilder, MSU Plant Pathology
Bill Cline, NCSU Plant Pathology

Leaf spot diseases are widespread in blueberries but tend to be more prevalent in the southern United States.

Symptoms
Septoria and Gloeocercospora spot are characterized by small to medium brown leaf spots with purplish margins; Gloeosporium spot causes larger reddish brown, irregular lesions on leaves. Both Septoria and Gloeosporium also cause lesions on succulent green stems. Severe leaf spotting can result in premature defoliation of bushes.


Septoria stem lesions.	Gloeosporium leaf spot.	Septoria leaf spot.

Disease cycle
Leaf spot infections occur on immature leaves; symptoms may take a month or more to become visible. Most leaf spots begin to appear in mid- to late season and are favored by wet weather. The causal fungi all produce rain-splash-dispersed spores and overwinter in infected tissues.

Management
Plant resistant cultivars; limit overhead irrigation; reduce humidity in the canopy; apply effective fungicides before the onset of symptoms.

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