What’s happening to birch trees in Southcentral and Interior Alaska?

(Fairbanks, AK) – Leaves on birch trees in several parts of Interior and Southcentral Alaska are turning yellow but it has little to do with a change in season.

Many of Alaska’s birch trees are being attacked by insects that leave the trees with yellow blotches on their leaves, causing the trees to look as though fall has come early. According to entomologists with the Alaska Division of Forestry and U.S. Forest Service, three invasive insect species, all native to Europe, are to blame for the damage. The amber-marked birch leafminer (Profenusa thomsoni), the late birch leaf edgeminer (Heterarthrus nemoratus), and the birch leafminer (Fenusa pusilla) are an annual nuisance to birch in many populated areas of Interior and Southcentral Alaska. All three species have been present in the state for more than a decade.

Surveys conducted along the Interior Alaska road system this summer indicate birch leaf mining damage is predominantly located in and around the cities of Fairbanks and North Pole. Two small populations were also observed on the Parks Highway between Fairbanks and Denali National Park, but no additional populations in the Alaska Interior were found.

In Southcentral Alaska, leafminer damage in birch has been especially noticeable along the Glenn Highway near Eagle River and around Palmer and Wasilla. Leafminer activity in Anchorage is much less prevalent than in the surrounding areas and surveys are ongoing to determine leafminer impacts in other areas of Southcentral Alaska.

For more information, contact Jason Moan at the Alaska Division of Forestry in Anchorage at (907) 269-8460 or jason.moan@alaska.gov or Stephen Burr at the U.S. Forest Service in Fairbanks at (907) 451-2701 or sburr@fs.fed.us.