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Question from Carlton, Salt Lake City, UT (received 5/2/20) -

I have a tannenbaum mugo pine tree planted in our front yard that is about three years old in Salt Lake City. The tree began to yellow/brown last summer and this spring the pine needles are covered in what appears to be pine scale but looks smaller and browner than the photos of pine scale found online. It appears they have a yellow inside when scraped off the needle. The spots are over nearly the entire tree. Is this indeed pine scale and, if so, what is the best treatment of the many available options?

Answer from Dr. Mike Kuhns, USU Extension Forester and Professor (sent 5/5/20) -

Carlton,

It appears that this is black pineleaf scale. This can be successfully treated using a systemic insecticide. The insecticide is sprayed on the bark of the trunk, where it is taken up through deep bark furrows. It can also be injected into the soil, where it is taken up by the roots. The chemical name is dinotefuran and the common name is Safari. It can only be applied by a certified applicator.

I would suggest visiting the USU Integrated Pest Management website for more information on black pineleaf scale. You may also find this management guide by the U.S. Forest Service useful

Good luck.