Blue spruce question

Asked January 1, 2020, 3:56 PM EST

We have a row of blue spruce behind our house planted by owners of a set of condos. The trees are about 25 feet tall. They are starting to thin out in the lower section of the trees. Roughly below the 12 ft height. The leaf dense is low enough that you can see through the trees. This thinning started about 2 yrs ago. There are about 50 trees. Is this nature and due to them being planted too close together? Could this be a disease?

Midland County Michigan

1 Response

This thinning is probably being caused by a fungal pathogen which causes the tree to lose needles from the previous year, while maintaining the new growth on the tips of the branches.
Colorado Blue Spruce are vulnerable to several fungal diseases here in Michigan, primarily because these trees are natives of a much more arid climate where damp conditions are not a problem. Some of these diseases are more treatable than others, so it is important to identify which fungus is affecting your tree by either sending a sample in to the Michigan State University Plant and Pest Diagnostic Lab, or by consulting a knowledgeable arborist. For more information on sending in a sample, go to and read about how and where to submit samples. If you would rather get an arborist onto your site, you can find an ISA-certified arborist on the site that is maintained by the International Society of Arboriculture. (It is always a good idea to check references in addition to using only ISA-certified arborists)
I am providing a link to a great article that explains all of the most common diseases of Colorado Blue Spruce, along with management and treatment options. At the bottom of the article is a link to a list of less problematic trees to consider when next planting.
I hope this is helpful!