Sitka spruce (Picea sitchensis) die-off French Beach

Observation by Jacob Earnshaw:

Many mature Sitka spruce trees dying off from French Beach south into Sooke along waterfront. Many dead partway up and needles thin.

Robin Mulvey, Forest Pathologist with the US Forest Service, writes:

To me, these lower crown symptoms appear consistent with either spruce aphid defoliation and feeding damage (most likely) or spruce needle cast/blight damage caused by foliar fungi. The trees are unlikely to die from this damage since upper crowns remain healthy. For a definitive diagnosis I would need to closely examine needles. In SE Alaska, spruce aphid damage is most common in coastal trees/forests following mild winters, since cold temps keep aphid populations and damage in check. Foliage diseases and spruce aphid primarily affect older needles. Elizabeth Graham is our forest entomologist, and I have several pathology contacts in BC. Alex Woods or Kathy Lewis (UNBC) or Richard Hamelin (UBC) may have information on historic spruce aphid activity or foliage disease near this location, but none can ID without close up pictures or samples. I have copied Elizabeth Graham on this message. We have detailed webpages on spruce needle casts/blights and spruce aphid on our website

Elizabeth Graham, Entomologist with US Forest Service writes:

That looks very spruce aphid like to me, but as Robin said I would need to see the needles to confirm. Temps were pretty mild this fall which helps the populations to build. I’m not sure how cold it got down there this past month but when I was looking at the spruce in Juneau I found most of the aphids had died after some long stretches of below freezing temps. There should be some good info and pictures on the website to refer to.