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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Annuals and Perennials > Zinnia > Discolored or spotted flowers

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Zinnia > Flowers > Discolored or spotted flowers

1 of 2
  • Bacterial leaf spot 1
  • Bacterial leaf spot 2
  • Bacterial leaf spot 3

Bacterial Leaf Spot
Xanthomonas campestris pv. zinniae

  • Small brown to black angular spots surrounded by yellow halos on leaves
  • Spots on petals are reddish and circular
  • Spots may merge together creating larger dead black areas that dry and crack
  • Disease starts on lower leaves and progresses up the plant
  • More information on Bacterial Leaf Spot (3.46 MB PDF)
2 of 2
  • Alternaria blight 1
  • Alternaria blight 2
  • Alternaria blight 3

Alternaria Blight
Alternaria zinniae

  • Reddish brown circular spots up to ½ inch in diameter appear on leaves and petals
  • Centers of spots turn grayish white
  • Center of an older spot may fall out giving the leaf a shot-hole appearance
  • Severely infected leaves, stems, and flowers turn brown and die
  • Dark brown sunken lesions (cankers) are common on the stem near the soil line
  • Warm, wet or humid weather favors disease
  • More information on Alternaria Blight (3.46 MB PDF)

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