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Septoria leaf spot (Sphaerulina westendorpii, formerly Septoria rubi) is a fungal disease of blackberry and black raspberry. Leaf spots are small, circular, and have whitish gray centers with purple borders; fruiting bodies are visible in centers of spots. Leaf spots often resemble anthracnose. Defoliation can occur if disease becomes severe. Canes and petioles develop lesions that resemble the leaf spots. The fungus overwinters in leaf debris or in infected canes. In spring, young, expanding leaves become infected. Secondary infections can occur throughout the growing season if conditions are rainy.

Septoria leaf spot early.

(Photo: Nicole Gauthier, University of Kentucky)

Septoria leaf spot advanced symptoms.

(Photo: Nicole Gauthier, University of Kentucky)

Management:

• Increase air circulation to encourage drying of plant tissues (pruning, thinning, spacing, and managing weeds).
• Apply fungicides.

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