Early Blight of Tomato
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Early blight (Alternaria spp.), the most common fungal disease of tomatoes in Kentucky, 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. Lesions may develop near the stem end of fruit during severe outbreaks. Fruit lesions become sunken and leathery; a thick mass of black spores may be present under humid or wet conditions.
Early blight on tomato foliage.
(Photo: Nicole Gauthier, University of Kentucky)
Severe early blight on tomato plant.
(Photo: Rebecca A. Melanson, Mississippi State University Extension, Bugwood.org)
Early blight on fruit.
(Photo: Yuan-Min Shen, National Taiwan University, Bugwood.org)
Management:
- Promptly remove and destroy diseased plant material
- Manage weeds and potential alternative hosts
- Avoid wetting fruit and leaves when irrigating
- Apply protectant fungicides
- Rotate with non-host crops
- Promptly destroy crop residues after harvest
- Deep plow to bury residual inoculum
