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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Annuals and Perennials > Marigold > Leaves discolored white, yellow or pale green

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Marigold > Leaves > Leaves discolored white, yellow or pale green

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  • Powdery mildew 1
  • Powdery mildew 2
  • Powdery mildew 3

Powdery Mildew
Golovinomyces (syn. Erysiphe) cichoracearum

  • Powdery, fluffy white spots and 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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  • Spider mite damage 1
  • Spider mite damage 2
  • Spider mite close up 3

Spider Mites
Tetranychus urticae

  • 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 spider mites
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  • Aster yellows 1
  • Aster yellows 2
  • Aster yellows 3

Aster Yellows
Phytoplasma

  • Part or all of the leaves may turn yellow
  • Flowers fail to develop, remain small green and may be distorted
  • Clumps of weak shoots known as witches broom develop throughout the plant or on flower stalks
  • More information on aster yellows

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