Knowledgebase

Oak galls? #851285

Asked September 26, 2023, 12:29 PM EDT

Hi, just looking at Northern oak the association planted in our yard last year. It has hundreds of hardish bald on it. Some larger than others. Can you tell me what this is and if I need to eliminate it?

Dakota County Minnesota

Expert Response

These are galls:
Insect and mite galls | UMN Extension

They are not uncommon. On oaks it is usually gall wasps. While the galls do take nutrients from the tree, very seldom are they prevalent enough to harm the tree. The infestations will vary from year to year. Treatment is generally not necessary but you want to treat the tree it is best done in the spring when the tree is leafing out with a chemical called Acephate. 

BTW, the tree is a Northern Red Oak.
Paul W. U of M Extension Master Gardener Dakota County Replied September 26, 2023, 6:26 PM EDT

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