An Or White oak has clusters of oak galls close to the main trunk. What does that tell us? - Ask Extension
We live in Corvallis and one of our Oregon White Oak trees has for several years had a fair amount of young growth along the main trunk of the tree (s...
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An Or White oak has clusters of oak galls close to the main trunk. What does that tell us? #832573
Asked May 29, 2023, 6:15 PM EDT
We live in Corvallis and one of our Oregon White Oak trees has for several years had a fair amount of young growth along the main trunk of the tree (see attached picture). This year we are seeing a lot more oak galls on that tree (compared to neighboring trees). Many of the galls are in numerically large clusters (not just one to a few galls per cluster, but half a dozen or more in a very tight cluster). Another unusual aspect of the oak gall clusters is how many of the clusters are right along the main trunk of the tree rather than out on the branches where we have mainly noticed them in the past. Both the number of galls per cluster and the location of the oak gall clusters may simply be a response to the amount of young growth happening along the main trunk of the tree. Are any of these features good, bad or neutral for the health of the Oregon White Oak? 1) clusters with many oak galls per cluster? 2) Most clusters close to the main trunk of the tree and/or 3) lots of young oak growth up and down the main trunk of the oak tree. See attached pictures.
Benton County Oregon
Expert Response
Hi Cliff:
Thank you for your questions regarding galls on your white oak, as well as advantageous branching, also known as epicormic branching.
Galls first. Oak galls are formed by a variety of tiny wasps called Cynipid wasps; in fact, there are over 200 species of Cynipid wasps that occur throughout the West!
Damage from these insects is usually cosmetic and therefore management is not necessary. Attacked trees often reflush their leaves as normal the following year.
Keep your eyes open for squirrels! Squirrels can debark white oak twigs in search of a wasp larvae meal. This debarking girdles the oak twigs causing a striking dieback of white oak branches. This damage generally will not kill an oak tree but can be an aesthetic issue.
Read more about oak galls here.
Now about those young shoots growing on the trunk you captured in your pic (thank you!). Epicormic branches are defined as shoots arising from adventitious or dormant buds on the stem or branch of a woody plant, often following exposure to increased light levels or fire. There are many causes, including environmental, like light exposure or lack thereof, and genetics.
Your white oak should be fine! It's always a good idea to watch for any change in your trees. Photo document and/or describe when and what you are seeing, if anything. There are instances, such as non-seasonal leaf loss and canopy thinning, that may be indicative of a more serious issue.
Please reach out should you have any more questions.
Thank you!
Thank you for your questions regarding galls on your white oak, as well as advantageous branching, also known as epicormic branching.
Galls first. Oak galls are formed by a variety of tiny wasps called Cynipid wasps; in fact, there are over 200 species of Cynipid wasps that occur throughout the West!
Damage from these insects is usually cosmetic and therefore management is not necessary. Attacked trees often reflush their leaves as normal the following year.
Keep your eyes open for squirrels! Squirrels can debark white oak twigs in search of a wasp larvae meal. This debarking girdles the oak twigs causing a striking dieback of white oak branches. This damage generally will not kill an oak tree but can be an aesthetic issue.
Read more about oak galls here.
Now about those young shoots growing on the trunk you captured in your pic (thank you!). Epicormic branches are defined as shoots arising from adventitious or dormant buds on the stem or branch of a woody plant, often following exposure to increased light levels or fire. There are many causes, including environmental, like light exposure or lack thereof, and genetics.
Your white oak should be fine! It's always a good idea to watch for any change in your trees. Photo document and/or describe when and what you are seeing, if anything. There are instances, such as non-seasonal leaf loss and canopy thinning, that may be indicative of a more serious issue.
Please reach out should you have any more questions.
Thank you!
