Needle cast is another fungal disease which primarily affects the Colorado blue spruce tree. Needle cast fungus, rhizosphaera kalkhoffi, thrives in damp cool conditions which are often seen in spring. Effective treatment and timing can quickly help trees recover and look beautiful again.
Symptoms: Affected trees will show bald patches on affected branches and areas where the needles have fallen off the tree. Dried patches suggesting drought stress may also be signs of needle cast infection.
More information: Penn State Extension, North Dakota State Extension