WSU Extension

Hortsense

Oak
 
Disease
Anthracnose 
Armillaria root rot 
Leaf scorch 
Mistletoe 
Sudden oak death 
Insect
California gallfly 
Jumping oak gall 
Leaf galls 
Oak leaf phylloxera 
Oak ribbed casemaker 
Oak treehoppers 
Pit scale 
Stem galls 
Western oak looper 



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Caption: Jumping oak galls
Photo by: A.L. Antonelli
  
Oak : Leaf galls
(revision date: 6/24/2015)


Biology
Leaf galls are caused by the feeding of several species of oak gall wasp larvae. Typical galls are enlarged or swollen plant tissues. These may assume several forms, depending on the species of wasp. Galls may be round, smooth, woolly, spiny, thorn-like, or dish-shaped. Colors vary from white to bright red to greenish, depending on wasp species and age of the gall. Many galls are formed on the leaves, but some may be found on twigs. Leaf deformities and twig dieback can result from infestations.
Management Options


Non-Chemical Management
  • Pick out and destroy galls when noticed (when practical). Many galls mature in the fall, so gall removal and destruction prior to this may help reduce numbers of wasps in the spring.
  • Prune out unsightly galls to improve tree's appearance, when practical.
Select non-chemical management options as your first choice!

Chemical Management

None recommended.

Images

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Caption: Jumping oak galls
Photo by: A.L. Antonelli