Any idea why I have about six trees out of forty that look like this? The trees right beside this one are fine but there’s a bit of red on a few of the really mature trees as well. The needles or leaves or whatever you call them aren’t really dry and dead either, just red and unhealthy? My neighbours have the same issue.
Cytospora canker, a fungal disease, is the most common reason for unnatural needle drop on Colorado blue spruce and several other spruce varieties
The fungal diseases are not common unless the tree is experiencing some stress due to outside conditions outlined below such as poor soil conditions, excess or not enough water salinity (if they have a pool in the area that has been draining into the water table around the trees)