The summer of 2015 was a hard one for our native trees. Lack of snow and unusually warm dry weather early in the spring put spruce trees into stress mode.
So for the first time in our part of the world, the Spruce Aphid (Elatobium abietinum) originally from Europe, has found its way to our green shores. The result has been browning needles and sad-looking spruce in the Homer area as well as Halibut Cove.
The mild winter provided an opportunity for these pests to begin active feeding and reproduction very early in the spring and so the damage was not noted until later in the growing season when the aphids were not visible. The warm summer also provided a second population flush in the fall, when more specimens were collected and trees presented the damaged needles.
What is a homeowner to do?
On a district wide level, there is nothing to be done but watch and wonder about what the changes of warmer weather might mean for our forests. At an individual location, options are available.
First in tree care is water. Trees respond to watering deep in the root zone once a week throughout the growing season. A healthy tree can withstand some insect feeding.
Inspection of your trees will help you note any early problems, so using a hand lens in late winter/early spring to ensure aphid populations are low will help you to react quickly.
Aphids are soft-bodied insects that can be dislodged with a strong water spray. There also are chemical treatments for homeowners; as always, read the label before buying or using any insecticide. Understand the timing and temperature needs for the ingredients to be useful, pollinator activity in the area, and proper method of application prior to application or purchase. Products ranging from a soil drench to a contact spray are registered for use in Alaska, but they require careful consideration and application.
If this is out of your comfort zone or you lack the equipment, consider hiring a professional arborist to work with you. They have the training, equipment and knowledge to assist landowners. After all, tree care is their business.
Since this insect is new to our area, correct identification is very important. USDA Forest Service, Alaska Division of Forestry and UAF Cooperative Extension are on hand to assist with information and have a publication on the spruce aphid in Southcentral Alaska which can be found online here: http://www.uaf.edu/ces/districts/kenai/
Finally, the sad fact is that all things have a life span, and even our beautiful trees which have withstood so much, may fall prey to a very small insect once again.
If you have further questions feel free to contact the Cooperative Extension Service office at 907-262-5824 or 1-800-478-5824 or firstname.lastname@example.org.
Stop by when you’re in Soldotna – the offices are open from 8 a.m.-5 p.m. Monday through Friday at 43961 K-Beach Road. We are happy to see you.
Janice Chumley is the integrated pest management tech and research tech for the Kenai Peninsula District of the University of Alaska Fairbanks Cooperative Extension Service.