Early Blight of Potato
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Early blight (Alternaria spp.) appears on leaves and stems as dark-brown lesions with concentric rings. Older leaves are usually affected first, but the disease spreads upward to newer growth under favorable conditions. Lesions enlarge and coalesce; extensive blighting (sudden death) and loss of leaves can result. Tubers are affected in severe outbreaks resulting in small, sunken, brown spots.
Early blight on leaf.
(Photo: Gerald Homes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org)
Early blight on tuber.
(Photo: Sandra Jensen, Cornell University, Bugwood.org)
Management:
- Select resistant cultivars
- Purchase pathogen-free seed stock
- Apply protectant fungicides
- Promptly destroy crop residues after harvest
- Rotate with non-host crops
