Red Oak dropping leaves

Asked August 10, 2014, 8:57 PM EDT


My Red Oak tree has started dropping clumps of dead leaves. The problem started in the crown about 8 weeks ago, and was dropping clumps of green leaves, now it is dropping clumps of brown leaves as well as green. It is also dropping sap from the places where the leaves drop. The tree is starting to look really thin, and the problem is definitely getting worse. Swingle said it had kermes scale, and treated it, but I think this is a different problem, and I fear we will lose this tree. Any help you can give in diagnosis and / or treatment is greatly appreciated.

Thank you,


Jefferson County Colorado

4 Responses

Your pictures and description are consistent with a Kermes scale infestation. To read more about the insect and management, please see this CSU Plantalk:

The insect can be aggressive, so you'll want to stay on top of the infestation.
Good luck!

Hi Mary,

Thank you for your response. In regards to the kermes infestation, I have read conflicting information on when and how it is best to apply the control. The link you sent says fall and winter, but Swingle and Mountain High both say during the summer months. Also, should it be a systemic application, or a spray at the base of the trunk, or a spray all over the tree? They each recommend different things, so it makes it difficult for me to know what is best.

Thanks again,


Most applicators have good luck with two applications per year, one in the spring or early summer and then another in late October or early November. The summer spray is usually a systemic, which moves through the plant's conductive tissue. Depending on the product used, it can be a trunk application. The fall application is often sprayed on the tree which kills the crawler stage. The crawlers aren't affected by the systemic products because they are on the tree and not yet feeding on the sap. Hope this helps!

Yes, it does help! Thank you very much for your time and knowledge.