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Extension > Garden > Diagnose a problem > What's wrong with my plant? > Deciduous Trees > Oak > Unusual growths or bumps on leaves

Oak > Leaves > Unusual growths or bumps on leaves

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  • Image: Jumping oak gall wasp 1
    Credit: J. Hahn, University Of Minnesota
  • Image: Jumping oak gall wasp 2

    Credit: T. Haugen Brown

  • - CLICK PHOTOS TO ENLARGE -

green arrowJumping oak gall wasp
Neuroterus saltatorius

  • Growths the size of BBs or small seeds on leaf undersides
  • Leaf upper surface has brown spots, 1/16 to 1/8 inch diameter, encircled by yellow halo
  • Foliage can be discolored or turn brown when leaves heavily infested
  • Can cause premature leaf loss
  • Commonly associated with white oaks
  • More information on Jumping oak gall wasp...
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  • Image: Oak leaf blister 1
    Credit: M. Grabowski, University Of Minnesota
  • Image: Oak leaf blister 2

    Credit: M. Grabowski, University Of Minnesota

  • Image: Oak leaf blister 3

    Credit: M. Grabowski, University Of Minnesota

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green arrowOak leaf blister
Taphrina caerulescens

  • 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
  • Heavy infestation will cause leaf to curl after the blisters have merged together
  • 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: Hedgehog gall 1
    Credit: J. Hahn, University Of Minnesota
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green arrowHedgehog gall
Acraspis erinacei

  • Soft, round tufted growth with orangish-reddish hairs on leaf surface; also found on underside attached to middle leaf veins
  • Ranges in size from ¼ to ½ inch
  • Commonly associated with white oaks
  • More information on Hedgehog gall...
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  • Image: Oak apple gall 1
    Credit: J. Hahn, University Of Minnesota
  • Image: Oak apple gall 2

    Credit: J. Hahn, University Of Minnesota

  • Image: Oak apple gall 3

    Credit: J. Hahn, University Of Minnesota

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green arrowOak apple gall
Amphibolips spp.

  • Spherical, smooth growths are dark greenish to brownish and up to 2 inch diameter in size and filled with spongy material
  • Found on leaf stem or vein in middle of leaf
  • Red and black oak are preferred hosts
  • More information on Oak apple gall...
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  • Image: Oak gall 1
    Credit: J. Hahn, University Of Minnesota
  • Image: Oak gall 2

    Credit: J. Hahn, University Of Minnesota

  • Image: Oak gall 3

    Credit: J. Hahn, University Of Minnesota

  • - CLICK PHOTOS TO ENLARGE -

green arrowOak gall
Cynipid wasps

  • Unusual swellings that are smooth, round and semi-circular bumps
  • Found on leaf surfaces
  • Range in size from ¼ to ½ inch; red to brown in color
  • More information on Oak gall...
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  • Image: Oak gall 1
    Credit: Brittany Koch, University of Minnesota
  • - CLICK PHOTO TO ENLARGE -

green arrowOak gall
Cynipid wasps

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