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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Oak > Leaves are curled, cupped or deformed

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Oak > Leaves > Leaves are curled, cupped or deformed

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  • Image: Oak anthracnose 1
  • Image: Oak anthracnose 2
  • Image: Oak anthracnose 3

Oak anthracnose
Discula quercina

  • Affected leaves become wrinkled, cupped or curled especially around leaf edges
  • Leaves have scattered brown, irregular spots that can coalesce into nearly completely brown leaves
  • On severely infected trees, leaves fall off early in the season, trees soon sends out new leaves
  • Damage is most common on lower and interior branches
  • Damage most common in spring as leaves are growing during wet weather
  • Most affected are trees within white oak group (white oak, bur oak, swamp white oak)
  • More information on Oak anthracnose...
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  • Image: Oak leaf blister 1
  • Image: Oak leaf blister 2
  • Image: Oak leaf blister 3

Oak leaf blister
Taphrina caerulescens

  • Heavy infestation will cause leaf to curl after the blisters have merged together
  • Raised blister-like leaf spots; appear sunken from the underside of the leaf
  • Leaf blisters are initially pale green to orange, but turn brown with age
  • Blister areas range from 1/16 to 1/2 inch in length
  • Leaves do not drop
  • Damage most common in spring as leaves are growing during wet weather
  • More information on Oak leaf blister...
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  • Image: Noxious oak gall 1
  • Image: Noxious oak gall 2
  • Image: Noxious oak gall 3

Noxious oak gall
Neuroterus noxiosus

  • Leaves become dwarfed, curled or shriveled
  • Tuber-like, irregular or potato-shaped growth that is ¼ to 4 inches long on branches
  • Associated with swamp white oak
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  • Image: Powdery mildew 1
  • Image: Powdery mildew 2
  • Image: Powdery mildew 3

Powdery mildew
Phyllactinia guttata

  • Severely infected leaves are often curled or distorted
  • White or gray powdery mats resembling talcum powder occur in spots, blotches or coat leaves
  • Lower shaded leaves are most commonly affected, common on small understory trees
  • Damage is common in spring or fall
  • More information on Powdery mildew...

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