Cooley Spruce Gall Adelgid (Adelges cooleyi)
GDD Window (base 50): 25-120 – spring control of overwintering females, 90-180 – 1st adults active (Douglas-fir), 210-310 – 1st galls visible (spruce)
Overview:
- Small, black, soft-bodied insect. Adults can be winged or wingless.
- Overwinters as an immature females in a crevice at the base of a spruce bud.
- Eggs are covered in a waxy thread, deposited around May.
- Eggs hatch when shucks break away from the buds, exposing new needles.
- Nymphs crawl into the new needles to feed, causing needle bases to swell, forming a 1-2″ gall shaped like a pineapple in which the adelgids reside.
- Some mature adelgids emerge from galls around July or August and fly to Douglas first to lay eggs which overwinter, producing a new brood in the spring, which can damage and distort trees but does not form galls.
- In late September, galls open and adelgids escape to produce overwintering females.
- Infested trees become disfigured, weakened, and vulnerable to pests and diseases.
- Host plants: Colorado blue spruce, Douglas fir, Sitka spruce, Engelmann spruce
Management:
Cultural Practices:
- Companion plantings: parsley, nasturtiums
- Traps: Sticky traps, monitoring traps
- Remove green colored galls before adelgids emerge and they turn brown
- Avoid planting spruce and Douglas-fir together
- Plant trees with generous spacing to allow for good air circulation
- Avoid tree stress
- Prune affected branches
Materials:
- Contact insecticides:
- Pyrethroids [3]: permethrin, cypermethrin
- Carbamates [1A]: carbaryl
- Systemic insecticides:
- Neonicotinoids [4A]: Imidacloprid (soil drench), Dinotefuran
- Considerations:
- Use with caution. Can harm beneficial insects and lead to resistance if overused. Apply before gall formation.
Biorationals:
- Insecticidal soaps
- Horticultural oils
- Mineral oil, neem oil
- Apply before bud break, or after galls have opened but before adelgids move to alternate hosts
Disclaimer – Materials do not cover all possible control scenarios and are intended for licensed professionals. Tradenames do not imply endorsement and are used as examples. You must strictly follow the label for each compound prior to use. Rutgers is not responsible form is used materials or damages thereof. The label is the law. Labels will provide detailed information on use and restrictions. Additionally, application intervals, compatibility, surfactant use, PHI, PPE, important and other key information is described in detail. Always discuss treatments with your local agents. Note: Neonicotinoids can only be legally applied in commercial agriculture settings by licensed applicators. Guidelines and recommendations made in this presentation are specific to the state of New Jersey.