Identification of Oak problem - Ask Extension
Dear CSU - A few oaks along my street have a little gall (not sure what else to call it) on the ends of the branches. It’s resulted in dead tips all...
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Identification of Oak problem #925785
Asked March 10, 2026, 2:09 PM EDT
Dear CSU - A few oaks along my street have a little gall (not sure what else to call it) on the ends of the branches. It’s resulted in dead tips all through the oaks. The HOA seems at a loss to help identify and treat. These are 22 year old trees that are so important to our neighborhood. Can you identify the culprit from a few photos I took last fall and attach to this note? And recommend what we can do to stop it, if possible? Or is it too late? Thanks for any help you can give.
Adams County Colorado
Expert Response
Susan,
All hope is not lost but treatment would be wise. You have kermes scale. Dormant oils applied before leaves emerge or systemic insecticide injections are likely to be the most effective. Any certified arborist is going to be able to do these applications.
For your reading here is some more information:
https://planttalk.colostate.edu/topics/insects-diseases/1400-11-kermes-scale-oak-trees/
https://yardandgarden.extension.iastate.edu/encyclopedia/kermes-scale
Do let me know if you have additional questions or if there are other issues that I can help with. I do site visits for HOAs and homeowners as well if necessary.
~ Cassey
All hope is not lost but treatment would be wise. You have kermes scale. Dormant oils applied before leaves emerge or systemic insecticide injections are likely to be the most effective. Any certified arborist is going to be able to do these applications.
For your reading here is some more information:
https://planttalk.colostate.edu/topics/insects-diseases/1400-11-kermes-scale-oak-trees/
https://yardandgarden.extension.iastate.edu/encyclopedia/kermes-scale
Do let me know if you have additional questions or if there are other issues that I can help with. I do site visits for HOAs and homeowners as well if necessary.
~ Cassey
