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Black Mold on Tomato

  • Alternaria alternata

Black mold is characterized by obvious lesions that appear on the surface of ripe fruit. Lesions are light to dark brown and vary from small flecks affecting only epidermal tissue to large, more or less circular, sunken lesions. During warm, humid weather the fungus may sporulate to form a black, velvetlike layer on the surface of the sunken lesions.

Solutions

Black mold is favored by wet conditions and high humidity. Avoid overhead sprinklers late in the season and keep beds dry. Pick fruit as soon as it ripens. Some varieties may show resistance.

Damaged fruit showing large, sunken black lesions; . Credit: Jack Kelly Clark, UC IPM
Sunken lesions of black mold on tomatoes. Credit: Jack Kelly Clark, UC IPM
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