Poplar: Poplar petiole gall aphids
Photo by: A.L. Antonelli
Biology
Aphids which cause galling of the leaf stem (petiole) are small, soft-bodied insects. The females lay eggs on tree bark in the fall.
The eggs hatch in the spring, and the aphids move to and feed on the petioles, which react by enlarging and enclosing the insects. The hard, pale green, rounded galls form along the petiole or at the base of the leaf. Aphids inside the galls are grayish and waxy in appearance.
The leaves are not damaged but may be turned at right angles to the petiole. Aphids emerge from the galls in midsummer and fly to a summer host, where they feed on roots until fall.
The aphids cause little damage to poplars but may be serious pests on alternate hosts such as lettuce.
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!
- Hose aphids from trees in fall with a strong stream of water.
- Natural enemies of aphids such as ladybird beetles, syrphid (hover) flies, green lacewings, and others help control aphid populations. Avoid use of broad-spectrum insecticides which kill these beneficial insects.
Chemical Management
IMPORTANT: Always read and follow label directions when working with pesticides.
For more information on using pesticides visit :
- Apply to foliage in early spring before gall reaction becomes widespread.
- 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.
WSU Extension programs and employment are available to all without discrimination.
Evidence of noncompliance may be reported through your local Extension office.