Drive out Lutak Road and you will see hundreds of evergreen trees that aren’t so green.
Southeast Alaska’s hemlock and spruce trees are fending off an assault by a number of pests and diseases, most notably a caterpillar that causes the conifers to turn reddish-brown.
“What we are seeing is multiple insects and some fungal diseases,” Haines state forester Greg Palmieri said in an email to the CVN. “All, at least as far as we can tell at this point, are indigenous to Southeast Alaska, and currently we are experiencing an increase in populations of the most common ones throughout the region.”
The main culprit is the western blackheaded budworm, a moth caterpillar that feeds on hemlock and spruce needles, according to U.S. Forest Service Alaska Region entomologist Elizabeth Graham.
Graham said forests across Southeast Alaska are experiencing a peak budworm infestation, a cyclical event that occurs every 30 or 40 years. While the widespread browning looks alarming, Graham said it’s not a big concern for general forest health.
“It’s actually endemic to the forest here. It’s not an invasive species or an exotic pest we haven’t dealt with before,” Graham said. “It may look really bad at first, but it’s part of the dynamic forest and how it’s changing.”
Budworms tend to feed on new growth, leaving older parts of the tree intact. And as they devour needles they create gaps in the forest, providing new habitat for wildlife and letting more light shine on the understory, Graham said.
She added that budworm poop, called frass, is also beneficial for the forest, infusing the soil with nutrients when it falls to the ground.
Forest managers first noticed the budworm outbreak in 2020. Infestations can last a few years, building up until the population crashes, Graham said. The last time there was a major outbreak in Southeast was 1992 to 1995.
The caterpillars prefer hemlock but this year they are feeding more on spruce, Graham said, likely because the population size grew and more moths laid eggs on spruce trees last fall.
“In coming weeks, the western blackheaded budworm will continue to feed and the damage will become even more apparent,” the Forest Service warned in its July 5 press release. “While most trees survive the damage caused by the budworms — and some trees may even benefit in the long term — heavy concentrations of activity can lead to the death of some trees.”
Other areas in Southeast Alaska have been hit particularly hard, Graham said, especially where a different insect called the hemlock sawfly is active.
Palmieri said in Haines he has also noticed spruce needle blight — a term that encompasses fungal foliar diseases including Lirula, Rhizosphaera and Lophodermium. He said some of the insects or diseases can cause mortality but “typically some additional stressor is acting upon the tree or trees to make them more vulnerable to attack.”
“I am always concerned when I see large outbreaks, as most people seem to be, but it is a natural part of the forest ecology and scientists from the (U.S. Forest Service) Forestry Sciences Lab in Juneau are monitoring conditions all over Southeast,” Palmieri said.
Graham and a colleague will do aerial surveys in the coming weeks in Haines and will have more information about the extent of the budworm outbreak here.