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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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
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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
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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
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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
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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
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Oak gall
Cynipid wasps
- Appear like dense balls of wool on leaf undersides
- ¼ to ½ inch wide
- Found along midvein and lateral veins
- More information on Oak gall
