Skip to Main navigation Skip to Left navigation Skip to Main content Skip to Footer

University of Minnesota Extension

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

Print Icon Email Icon Share Icon

Oak > Leaves > Unusual growths or bumps on leaves

1 of 6
  • Image: Jumping oak gall wasp 1
  • Image: Jumping oak gall wasp 2

Jumping 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...
2 of 6
  • Image: Oak leaf blister 1
  • Image: Oak leaf blister 2
  • Image: Oak leaf blister 3

Oak 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...
3 of 6
  • Image: Hedgehog gall 1

Hedgehog 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...
4 of 6
  • Image: Oak apple gall 1
  • Image: Oak apple gall 2
  • Image: Oak apple gall 3

Oak 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...
5 of 6
  • Image: Oak gall 1
  • Image: Oak gall 2
  • Image: Oak gall 3

Oak 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...
6 of 6
  • Image: Oak gall 1

Oak gall
Cynipid wasps

Don't see what you're looking for?

  • © Regents of the University of Minnesota. All rights reserved.
  • The University of Minnesota is an equal opportunity educator and employer. Privacy