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Alternaria leaf blight (Alternaria cucumerina) is found primarily on watermelon and muskmelon but may occur on cucumber, gourds, pumpkin, and squash. This disease affects foliage and sometimes fruit. Symptoms appear on older leaves first, as small, necrotic spots that may be surrounded by a yellow halo. Lesions expand to form large brown spots with a concentric ring pattern. As lesions expand, they may merge to form large, blighted areas followed by curling of leaves and eventual decline.

Alternaria leaf blight on muskmelon foliage.

(Photo: Kenny Seebold, University of Kentucky)

Close-up of Alternaria leaf blight lesions.

(Photo: Kenny Seebold, University of Kentucky)

Management:

• Crop rotation
• Sanitation (removal of crop debris)
• Planting of resistant varieties (muskmelons)
• Fungicides

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