Home and Landscape

Early Blight on Tomatoes

  • Alternaria solani

Symptoms of early blight include black or brown spots, usually about 1 cm in diameter, that appear on leaves, stems, and fruit. Leaf spots are leathery and often have a pattern of concentric rings. They usually appear on older leaves first. Fruit spots are sunken and dry and also have a concentric pattern.

Solutions

Spores of early blight are carried by wind and require moisture for germination and infection. The disease can cause severe damage if conditions remain cool and humid for several days after a rain. Avoid overhead irrigation. Crop rotation is useful in infested gardens. Copper fungicides applied at the first sign of infestation and repeated every 7 to 10 days may provide control.

Spots on green fruit caused by early blight; . Credit: Dennis H. Hall
Fruit spots caused by early blight. Credit: Dennis H. Hall
Foliage damage showing collar rot phase of early blight; Florida. Credit: Jack Kelly Clark, UC IPM
Spots on stems. Credit: Jack Kelly Clark, UC IPM
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