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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Crab Apple > Spots on leaves

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Crab Apple > Leaves > Spots on leaves

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  • Image: Apple Scab 1
  • Image: Apple Scab 3

Apple Scab
Venturia inaequalis

  • Olive green to brown leaf spots with an irregular or feathered edge, eventually becoming a dark brown to black
  • Infected leaves turn yellow and drop prematurely
  • Brown raised corky spots on fruit
  • Severely infected fruit may be deformed and cracked
  • More information on Apple Scab...
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  • Image: Cedar-Apple Rust 1
  • Image: Cedar-Apple Rust 3

Cedar-Apple Rust
Gymnosporangium juniperi-virginiana

  • Leaves develop yellow, then bright orange spots with a red border
  • Small raised black dots may be present on the upper side of leaf spots, fringed tubes may be seen on the underside of the leaf spots
  • Rough green to brown irregular spots on fruit, do not extend deep into the fruit
  • Juniper bushes have brown 1/4 – 1 inch round woody galls, that produce bright orange tentacles in wet spring weather
  • More information on Cedar-Apple Rust...
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  • Image: Black Rot 1
  • Image: Black Rot 2

Black Rot
Botryosphaeria obtusa

  • Round leaf spots with a purple border & tan center
  • Large brown spots with brown rings form on fruit
  • Fruit is rotted but remains firm
  • Fruit may become mummified and remain on tree
  • Branch cankers can be sunken, reddish brown or rough looking or cracked bark; cankers may remain small or enlarge to become several feet long
  • Leaves on girdled branches wilt, die and turn brown
  • Common on stressed trees & trees infected with fire blight
  • More information on Black Rot...
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  • Image: Powdery Mildew 1<
  • Image: Powdery Mildew 2

Powdery Mildew
Podosphaera leucotricha

  • Part or all of infected leaves are covered in white-gray, felt-like patches
  • Infected leaves will curl, twist, or fold upward
  • Infected blossoms are distorted, discolored, and covered in white powdery fungal growth
  • Infected fruit have bronze, corky streaks, that are skin deep
  • More information on Powdery Mildew...
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  • Image: Spotted Tentiform Leafminer 1
  • Image: Spotted Tentiform Leafminer 2

Spotted Tentiform Leafminer
Phyllonorycter blancardella

  • Feeding by larvae in between the leaf surfaces results in small, oval, spot-like “mines”, opaque at first, later turning brown
  • This can reduce photosynthesis, resulting in diminished fruit set and quality, and can also cause premature leaf and fruit drop when leaves are severely infested
  • Adult moth is small (1/10”), slender, brown, with distinct gold, black, and white wing patterns; They are present from early May – September
  • Larvae are yellow-green and small (1/10” in length when mature); they are present from late May - August

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