Spruce Rust (Chrysomyxa ledicola) Appearing on Spruce Trees (Picea mariana)

Observation from Wilson Justin:

The spruce along the highway between mile 157 and 162 show signs of stress, the tips of the branches are orangish and the deep green of the trees are fading. First noticed the change on the Nabesna Road a couple of years ago and mentioned it to Park Service personnel. Originally I thought of water deprivation but in many places where I've noticed the small scale changes it's both dry and wet. The outbreak at Nelchina is much more dramatic and much quicker. One summer whereas up at Twin Lakes on the Nabesna Road its been at least 5 years since I first notice the orange tips.

Comment from Matt Lorenz:

I have had a couple of friends ask if I had noticed it as well. I did notice it also the last time I went to Anchorage. I’m not sure who exactly I could ask about that or what would be the difference with that stretch of road/land. One likely possibility (suggested by Rita Stadtmiller who lives at 163.5 mi Glenn) is Spruce Rust. I looked online and found a good write-up from USDA Forest Service AK Region. I’ll publish in the paper the next time I have space. According to the FS, it only bothers new needles and is mostly a cosmetic problem that rarely kills trees. I guess the test will be how they look next year.

Robin Mulvey, Southeast Alaska Forest Pathologist with the U.S. Forest Service, writes:

The damage in this location was caused by spruce needle rust. This disease causes trees to have an orange tinge when they are heavily infected, and damage is restricted to current-year foliage (new growth, tips). Our spruce needle rust webpage has a lot of information about where this disease has been detected before; it is very widespread in Alaska within the range of spruce (and the alternate host Labrador tea) and has periodic severe outbreaks when the conditions are right. We have had reports of severe disease at many locations this year and will incorporate all of these observations into our annual conditions report write-up. Thanks for the observation! This disease may reduce tree growth this year in affected areas, but does not typically have long-term impacts on tree health since outbreaks don’t generally occur in the same location year after year.

Comments from LEO Editors

Spruce needle rust affects trees in the southeast, southcentral, and interior parts of Alaska. The fungus that causes spruce needle rust only affects new needles, which distinguishes it from other diseases that cause discoloration in spruce trees such as spruce needle cast or broom rust. For more information, see the attached Spruce Needle Rust publication from the US Forest Service. Erica Lujan