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

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Petunia > Flowers > Discolored or spotted flowers

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  • Petunia aster yellows 1
  • Petunia aster yellows 2
  • Petunia aster yellows 3

Aster Yellows
Phytoplasma

  • Leaves are small and yellow on a few to all stems
  • Flowers are small pale green to white and underdeveloped
  • Clumps of weak shoots known as witches broom develop throughout the plant
  • Infected plants are often stunted
  • Often one to a few random plants within a flower bed are infected while others remain healthy
  • More information on Aster Yellows
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  • Powdery mildew 1
  • Powdery mildew 2
  • Powdery mildew 3

Powdery Mildew
Oidium sp.

  • Powdery, fluffy white spots or blotches on leaves, stems, and flower parts
  • Tiny black round spheres may be visible within white spots late in the season
  • Spots typically start on lower leaves but can spread to cover the entire plant
  • Severely infected leaves may be completely covered in white or grayish white fungi
  • In some cases, leaves become curled or twisted or turn yellow due to the infection
  • More information on Powdery Mildew
3 of 4
  • Petunia gray mold 1
  • Petunia gray mold 2
  • Petunia gray mold 3

Gray Mold
Botrytis cinerea

  • Large brown spots or blotches on leaves
  • Leaves or entire plant may be completely blighted, brown, and wilted
  • Blossoms or petals may turn brown and drop off prematurely
  • Gray fuzzy mold develops on rotted tissue under humid conditions
  • Disease develops during cool, wet weather
  • More information on Gray Mold
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  • Tobacco mosaic virus 1
  • Tobacco mosaic virus 2
  • Tobaco mosaic virus 3

Tobacco Mosaic Virus (TMV)

  • Symptoms may vary depending on cultivar, age of plant and other factors
  • Leaves have a mosaic pattern of light and dark green
  • Leaves may be distorted, curled or twisted upward
  • Lab test needed to identify which virus is causing the problem
  • More information on TMV

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