Douglas Fir: Cooley spruce gall adelgid
Photo by: A.L. Antonelli
Biology
This aphid-like insect feeds on newly growing needles. adelgids appear as woolly or cottony tufts on the needles, with heavily infested trees appearing “frosted” or flocked.
Small purplish insects are found underneath the cottony tufts. Adelgid feeding can cause needles to become distorted or bent and yellowed. Infested needles sometimes drop prematurely.
This pest is a serious concern in Christmas tree plantations but is less important in the landscape. Cooley spruce gall adelgids also infest spruces but cause distinctive galls on spruce that are not seen on Douglas fir.
Chemical control must be aimed at crawlers during or shortly after bud-break.
Management Options
See "Using Integrated Pest Management (IPM) in the Landscape" for successful problem management techniques.
Non-chemical Management
Select non-chemical management options as your first choice!
- Planting spruce and Douglas fir trees as far apart as possible may help reduce adelgid infestations.
- Hand-wipe to control minor infestations (where possible).
Chemical Management
IMPORTANT: Always read and follow label directions when working with pesticides.
For more information on using pesticides visit :
- Apply to control crawlers when new tips are expanding.
- Esfenvalerate is toxic to bees. Do not apply products containing esfenvalerate on or near blooming plants.
- To minimize risk to bees, apply in the evening after bees have stopped foraging for the day.
- Homeowners should not make foliar applications to trees over 10 ft tall. Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.
Approved Pesticides
If you choose to use a pesticide, some examples of products that are legal in Washington are listed below. Some products are labeled for just INDOOR or just OUTDOOR use, or may allow both uses. Be sure to choose a product appropriate for your situation. Always read and follow all label directions.
Additional Image
Photo by: C.R. Foss
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Evidence of noncompliance may be reported through your local Extension office.