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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Vegetable > Tomato > Dark spots on stems

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Tomato > Stem > Dark spots on stems

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  • Image: Early Blight 1
  • Image: Early Blight 2
  • Image: Early Blight 3

Early Blight
Alternaria solani

  • Infects leaves, stems and fruit
  • Black leathery spots on fruit start on stem end
  • Dark irregular leaf spots, often surrounded by yellow tissue
  • Sunken dark round stem lesion with concentric circles inside
  • Occurs in warm wet weather, common at the end of summer
  • More information on Early Blight...
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  • Image: White Mold 1
  • Image: White Mold 2
  • Image: White Mold 3

White Mold
Sclerotinia sclerotiorum

  • Dark, firm water-soaked lesion on stem
  • Girdled stems die and turn bone white
  • Inside dead stems are black mouse poop shaped sclerotia
  • Fruit are soft and rotted
  • Cottony white mycelia inside and outside infected stems when humidity is high
  • Favored by cool humid conditions
  • More information on White Mold...
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  • Image: Late Blight 1
  • Image: Late Blight 2

Late Blight
Phytophthora infestans

  • Irregular watersoaked lesions on leaves, turn olive then brown
  • Leaves, stems and petioles turn brown and shrivel
  • Fruit spot is round olive colored, can cover whole fruit
  • Infected tissue is covered with white mycelia is wet weather
  • Disease spreads very rapidly in cool wet weather
  • More information on Late Blight...

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