What's Causing the Bare Branches on My Colorado Blue Spruce Tree?

Aphids or the Cooley Spruce Gall Adelgid, Most Likely

Image of Colorado blue spruce tree.
The color of the needles of Colorado blue spruce tree (foreground) make it a popular landscape plant. David Beaulieu

Question: What's Causing the Bare Branches on My Colorado Blue Spruce Tree?

"I was given a Colorado blue spruce tree as a gift. We have had it for about 6 weeks now (August) and it looks as though it's dying. The branches are shedding and some of the top ones are almost bare. What can I do to save this beautiful 7 1/2-foot tree?"

Answer:

The symptoms you report are common for Colorado blue spruce trees and often attributed to either of two insect pests: aphids or the Cooley spruce gall adelgid.

You may need some help with identification, though.

These two insect pests look similar. However, it's easy to tell if you have an infestation of Cooley spruce gall adelgid: Adelgids leave a cotton-like substance (their egg sacs) behind on tree branches.

If you see insects on your Colorado blue spruce tree upon inspection, try spraying first with Neem oil. It's organic, and it won't hurt to see if the Neem oil can solve the problem.

For ongoing problems with these insect pests, you can take preventive measures -- but it requires good timing. For aphids, you can spray in January -- that's when their life cycle begins. In case it's Cooley spruce gall adelgid, apply a dormant oil spray in late-October and early-November. You can't spray actively growing trees (your Colorado blue spruce tree is actively growing right now, in August) since that may cause new growth to burn.