University of Florida

Early Blight

Fungus

Alternaria solani

Infects

Foliar plant parts and fruit.

Symptoms

Young leaf spots appear brownish-black on older foliage, spots expand beyond 1/4 in becoming zonate with a yellow halo; stem lesions appear small, dark and sunken, expanding to elongate, zoned lesions, girdling may occur at the soil line; fruit spots occur at the calyx end of ripe or green fruit, lesions enlarge to one inch or more in diameter, appear leathery, zonate and velvety black due to funnel sporulation and penetrate to 1/2 in into the fruit.

Pathogen Spread

Rain-splashed from viable fungus on host plant debris, volunteer tomatoes or weed hosts.

Favorable Conditions

Rainy, humid weather above 75 F. A mid- to late winter problem, occasionally, in peninsular Florida.

Early Blight Pictures

early blight
Image # 130.
Early blight
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leaf spots 1/4 to 1/2 in. diameter with obvious concentric zones present.

early blight
Image # 131.
Early blight-
stem lesions are circular to elliptical with a typically zonate appearance.

Early blight fruit lesion
Image #132.
Early blight-

fruit infections appear scattered with definite zonate patterns in the fruit lesion