Spruce Bark Beetles moving into Girdwood Valley
Spruce Bark Beetles moving into Girdwood Valley
By Luke Smithwick
Turnagain Times correspondent
Spruce bark beetles have plagued the Kenai Peninsula for the last decade, and now they are moving into the Girdwood Valley.
“A warm, dry summer like we had in 2005 allowed spruce bark beetles to move into the Girdwood Valley,” said Sue Barkwood, the Firewise Home Assessment Coordinator for the Girdwood Valley.
Spruce in the Girdwood rain forest is used to a certain amount of water being available consistently in summer growth months. When that amount of water is reduced, even slightly, the trees become stressed. Warmer than average temperatures increases drying and evaporation, further stressing the trees. Spruce bark beetles sense stressed trees, and will attack those trees first.
“Many of the spruce trees of the Girdwood Valley are nearing the end of their life cycle, so many of them are already diseased or inhabited by other bugs,” said Barkwood. These trees, she said, serve as perfect hosts for incoming spruce bark beetles.
“Warm, dry summers are so prime for spruce bark beetles that they even attack healthy trees,” said Michael Rasy of the Alaska Integrated Pest Management Program.
Many Girdwood residents are growing concerned as this epidemic gets ever closer to home.
“To keep the spruce around in your yard, it’s important to take care of them,” said Barkwood.
First, homeowners must distinguish between their young and old trees as beetles typically will not attack young, barkless spruce, as there is very little food for growing larvae.
As for the older trees, “there are two methods for protecting them, culturing or spraying,” said Barkwood.
Culturing involves watering the tree in times of drought, fertilizing in the spring, and avoiding pruning or cutting limbs in the spring and summer months. Pruning during the warm months leaves trees open to infestation and disease. Spraying, the other option, is done before beetles begin flying in mid to late May. Spraying is only a preventative measure. Once beetles have attacked a tree, spraying is ineffective.
According to Rasy, timeliness is of the essence. Early detection of the spruce bark beetle could make all the difference. “It’s important that you spray or remove infested or dead spruce trees before the beetles start flying in mid-May though, because by then its too late,” said Rasy. “The trees you see with red or gray needles were infested several years ago.”
Signs that beetles are active in the spruce are red bore holes and boring dust on the outer bark of the spruce. Discolored needles are a sign of a late stage of infestation. If you have trees in your yard at this stage then they need to be removed as soon as possible.
In order to help residents to respond proactively rather than reactively, Rasy encourages residents to get to know the beetle up close and personal.“It’s important to understand the life cycle of the beetles, as this will keep you savvy on keeping the spruce in your yard healthy,” he said.
According to the Alaska Cooperative Extension Service, some spruce beetle species take two years to complete their life cycle, while others take only a year. In mid to late May, the beetles come out from the base of their host tree, fly to a new tree, and burrow into the bark. As soon as they reach the phloem layer just under the bark, they lay their eggs. Pupae are born within a few weeks and begin feeding on the phloem layer of the trees, which is the fatal blow to the spruce. As they continue feeding, they slowly grow into full grown beetles. By fall, they make their way down to the base of the tree, where they spend the winter.
Seasonal variations can have an effect on the life cycle of the beetle. Cold, wet summers like 2006 aren’t very favorable for the beetles, and they won’t reproduce or attack as many trees during these summers. Predators such as the three-toed woodpecker tend to keep the beetle populations in check as well. Presence of woodpeckers feeding on your property is indicative of beetle or other pest infestation.
There are a number of services available to come and spray your spruce trees, and the Anchorage Fire Department recommends you first contact them to set up a free Firewise Home Assessment (http://www.muni.org/fire, 907-267-4980). Doing this will not only help the spruce trees in your yard but also give you the information you need to make your property ready for the unexpected wildfire.
Beginning in May, the Anchorage Fire Department will offer a wood lot in Girdwood for the summer. This is a great place to bring old and rotting debris from your yard, which is prime host material for beetles and other pests. It will be open Saturdays from 9 a.m. to 6 p.m. The exact location is to be announced. You can check back at http://www.muni.org/ fire1/Woodlots.cfm or call 267-4980.
Open burning is another option and is allowed for spruce bark beetle killed wood on your property. You must apply for a permit (http://afd.muni.org/ or 907-267-5020), and call on the day of your planned burn.
Photo: A spruce bark beetle killed this spruce tree in front of a residence located on Crow Creek Road.