Weird stuff on my linden tree leaves

(Question)

Hello. I have noticed weird stuff on my linden tree leaves. It comes every year for at least last three years. Some leaves look normal even with that stuff, but others took completely deformed. Overall the whole tree looks good, it continues to grow. I am concerned as I don’t know what it is and if it will damage my tree seriously eventually. I love my tree and I want it to continue growing. I took a picture and I can provide more if needed.
Your answer is very appreciated. Thank you.

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(Answer)

Hi,

I believe you are seeing spindle galls on the leaves of your linden and don’t worry as they rarely threaten the health of any affected tree. Spindle galls are caused by tiny Eriophyid mites. They are blown by the wind or carried to your tree by birds and insects. The adult females overwinter in cracks in twigs and lay their eggs in the spring. Each can lay up to 80 eggs in a month and each egg will develop into an adult in one to two weeks. The adult feed by sucking up the contents of plant cells. To protect itself, the linden forms a barrier of plant tissue that is the gall.

Spindle galls are formed on leaves and resemble the spindle of a spinning wheel – shorter at the ends than in the middle, hence the name. So the weird stuff you are seeing has been produced by the linden itself as a protection against the mite. You may find that the number of galls varies considerably from year to year. The damage caused by the galls is cosmetic so control is not recommended.

To read more about Eriophyid mites and spindle galls, click on the link below to access a good article on the gardenguides.com web site:

Linden Eriophyid Gall Mite Control