Tannenbaum Pines

Asked August 18, 2020, 3:08 PM EDT

We had several new trees (tannenbaum pines) planted last summer in a newly landscaped area. Looked good until recently. We applied spike fertilizer on landscapers advice in spring and watered once a week when there was no rain. Now noticing inner needles have turned brown and that they are striped or banded (see photo). I'm concerned that they have a disease. Can you tell me what is happening? I have questions about two other trees that I will send separately. Thank you, Sue B (pushed submit button several times-no indication that it is sending-apologize if you get duplicates!!)

Wright County Minnesota

1 Response

A needle disease may be affecting the trees but we can’t provide a certain diagnosis by viewing the photos.

We recommend asking a certified arborist to assess the trees’ health onsite to confirm or rule out this possibility.

If you decide to do that, this information may be useful.
https://extension.umn.edu/planting-and-growing-guides/how-hire-tree-care-professional

In lieu of that, consider sending samples of the affected branches to the University of Minnesota Plant Disease Clinic. Go here to learn how to prepare samples:
https://pdc.umn.edu/submit-sample

Following is information about a common needle disease that sometimes affects mugo pine:
https://hortnews.extension.iastate.edu/2006/2-8/dothistroma.html