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Septoria leaf spot or Septoria leaf blight (Septoria lycopersici) symptoms are usually first observed in lower plant canopies but can spread upward to newer growth. Circular lesions with darkened borders and tan-brown centers can be numerous; under favorable conditions, severe blighting (sudden death) occurs. Small, black specks (pycnidia) are often found in the centers of older lesions. Disease is favored by moderate temperatures and high humidity/rainfall.    

Septoria leaf spot.

(Photo: Kenny Seebold, University of Kentucky)

Management:

• Promptly remove and destroy diseased plant material
• Manage weeds (potential alternative hosts)
• Avoid wetting leaves when irrigating
• Apply protectant fungicides
• Rotate with non-host crops
• Promptly destroy crop residues after harvest
• Deep plow to bury residual inoculum

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