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

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Petunia > Leaves > Discolored leaves

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  • Aster yellows 1
  • Aster yellows 2
  • 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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  • Image: gray mold 3
  • Image: gray mold 2
  • Image: gray mold 1
  • - CLICK PHOTO TO ENLARGE -

Two-Spotted Spider Mites
Tetranychus basicola

  • Active during summer, particularly abundant during hot, dry weather
  • Pale stippling appears on the upper leaf surface
  • Leaves are discolored off green to whitish, yellowish, or bronze
  • Premature leaf drop can occur
  • Visible webbing occurs on infected leaves when populations are high
  • Adults are tiny (1/50th inch long) and oval, greenish or yellowish with a dark spot on either side of the body
  • More information on Two-Spotted Spider Mites (86 K PDF)
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  • Image: gray mold 3
  • Image: gray mold 2
  • Image: gray mold 1

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
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  • Tobacco mosaic virus 1
  • Tobacco mosaic virus 2
  • Tobacco 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 (517 K PDF)

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