Spruce Needle Rust Fungi
Most days, we walk trails near our house to a place we call “the overlook” because it is has views high above King Salmon Creek and the Naknek River.
A few days ago, I noticed that the spruce trees on the way were orange-yellow at the tips. It looked like an infestation. My first thought was that it might be dangerous for Kiva, our Australian Shepherd.
When I got home, I looked it up and discovered it was spruce needle rust fungi, or more technically, Chrysomyxa ledi or Chrysomyxa ledicola.
It is caused by a fungus that has two hosts. The first host can be Labrador tea (bingo!), leather leaf, or bearberry. In the spring, the first host releases spores that, with the help of the wind, infect the current year spruce needles, but do not infect any of the other needles. Cool, wet weather is needed for the fungal infection to take hold. By mid-summer, the current year spruce needles release spores that resemble an orange powder.
The good news is that it doesn’t kill the tree. The infected needles will die and fall off in the fall and new growth will continue in the next year.
If you’d like to try to get rid of it anyway, the fungus is not spread back to the spruce tree, but infects the first host, so the best thing to do is to remove Labrador tea, leather leaf or bearberry that are near the infected spruce trees.
I wasn’t able to find out if it can be harmful to dogs, so I’m walking Kiva away from it just in case.
Sources:
Scientific American. Mystery of Alaskan “Goo” Rust Solved at Last.