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Yellow spots on tree leaves #869682

Asked May 22, 2024, 7:41 PM EDT

I have what I believe is a buckthorn in my yard and the leaves are covered with yellow spots. There also seems to be a lot of gnats or some other type of tiny flying insect hovering around the tree. This has not happened in previous years.

Hennepin County Minnesota

Expert Response

Thank you for writing.
These are galls.  Essentially a gnat, mite, or small wasp bites the leaf and a bacteria or virus enters.
You are an astute observer to wonder if the gnats had anything to do with this. 
https://www.britishplantgallsociety.org/buckthorn/

Unfortunately, it will not damage your buckthorn.  Pull them out. https://extension.umn.edu/yard-and-garden-insects/insect-and-mite-galls
The easiest way for plants this size is a brush root puller that can be rented at garden equipment rental stores.  With perseverence your buckthorn will get smaller and rarer.
Steve Miles, Master Gardener, Hennepin County MN (I am a human being, not a bot nor AI). I am an avid gardener but am not a degreed or certified horticulturist or arborist. I am happy to receive follow-up questions if my responses are incomplete or unclear.  This is the University of MN' garden soil testing service.  https://soiltest.cfans.umn.edu/testing-services/lawn-garden This is guidance on how to find a tree expert.  https://extension.umn.edu/planting-and-growing-guides/how-hire-tree-care-professional The Minnesota Landscape Arboretum is a wonderful place to see and learn about plants that grow in Minnesota. https://mngardens.horticulture.umn.edu/minnesota-landscape-arboretum Replied May 22, 2024, 8:21 PM EDT

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