My 40' spruce tree, which I believe is a Colorado, has a definite
pattern of a yellow spiral from top to bottom.

Root damage on a spruce tree typically shows up in a spiral as the xylem and
phloem in this tree spirals the trunk.
Spruce have very shallow root systems that are easily damaged by foot traffic,
too much water, construction problems or a lack of room to expand. When one
section of the root system is damaged, you see the results in the part of the
tree that it supplied.
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