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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Annuals and Perennials > Snapdragon > Spots or blotches on leaves

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Snapdragon > Leaves > Spots or blotches on leaves

1 of 5
  • Powdery mildew 1
  • Powdery mildew 2
  • Powdery mildew 3

Powdery Mildew
Oidium sp.

  • 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
2 of 5
  • Snapdragon rust 1
  • Snapdragon rust 2
  • Snapdragon rust 3

Snapdragon Rust
Puccinia antirrhini

  • Yellow spots or blotches can be seen on the upper surface of infected leaves
  • Raised brown pustules form on lower leaf surface primarily and grow in concentric rings with age
  • Powdery reddish brown spores rub off on hands and tools
  • Severely infected leaves wilt and die
  • Plants can be stunted and may fail to bloom
  • Disease develops during cool (below 60°F) weather
  • More information on Snapdragon Rust
3 of 5
  • Gray mold 1
  • Gray mold 2
  • Gray mold 3

Gray Mold
Botrytis cinerea

  • Brown spots or blotches on leaves or stems
  • Brown spots or blotches on flowers; flowers drop off prematurely
  • As disease progresses, entire leaves, flowers and shoots turn brown
  • Gray fuzzy mold develops on rotted tissue under humid conditions
  • Disease develops during cool, wet weather
  • More information on Gray Mold
4 of 5
  • Downy mildew 1
  • Downy mildew 2

Downy Mildew
Pernospora antirrhini

  • Leaves turn pale green to yellow and may curl slightly downward
  • Downy white fungal growth on underside of leaves
  • Plants become yellow in color and stunted
  • Infected leaves prematurely drop from the plant leaving a barren stalk with few leaves
  • Disease favors cool, wet weather
  • More information on Downy Mildew
5 of 5
  • Oedema 1
  • Oedema 2


  • Pale-green to white blisters or bumps on the undersides of leaves
  • Blisters brown with age and have a crusty or corky appearance
  • Older leaves are more affected than younger ones
  • Occurs when plants are overwatered during cool or humid weather
  • More information on oedema

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