Septoria leaf spot of grape

Septoria ampelina

The disease mainly affects American Vitis and muscadine grapes. Angular, reddish brown to black spots that are 1 to 2 mm in diameter appear after midseason. Nearing veraison, lesions become larger with diffuse margins. Fruiting bodies may be seen with a hand lens. The area surrounding the spots may be yellow. The fungus overwinters in infected leaf debris.

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