Ornamental Plum: Hop aphid

• Categories: Ornamental Plum Ornamental Plum Insects Ornamental trees Ornamentals
• Last review date: 2026-08-29 08:19

Biology

Hop aphids are yellowish to bluish green in color. They feed on plum, prune, cherry, and other hosts in the winter, then migrate to a summer host such as hops or sunflower.

Some aphids remain on the winter host all year round. Their feeding causes leaves to roll. Typically, they are found on the underside of plum leaves, or inside the rolled leaves.

Heavily infested plants may drop leaves, resulting in severe defoliation.

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!

• Wash aphids from plants with a strong stream of water (most effective before leaves are rolled).
• Remove aphids by hand and hand-pick rolled leaves (when practical) to control small infestations.
• Natural predators and parasites, including ladybird beetles, lacewings, and parasitic wasps, help control aphid populations.
• Control honeydew-feeding ants, which may protect aphid colonies.
• Provide proper nutrition. High levels of nitrogen in the foliage encourages aphid reproduction. Switch to a slow-release or low-nitrogen fertilizer.

Chemical Management

• Thorough coverage of the foliage is important, including lower leaf surfaces (follow label instructions for products applied as a drench).
• Apply oils in early spring before bud swell.
• 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.

• Hi-Yield Dormant Spray
  Active ingredient: Paraffinc oil
  EPA registration number: 7401-428
• R-T-U Year-Round Spray Oil
  Active ingredient: mineral oil
  EPA registration number: 6218-78
• Safer Brand Insect Killing Soap Concentrate II [Organic]
  Active ingredient: potassium salts of fatty acid
  EPA registration number: 42697-60
• Azera Gardening [Organic]
  Active ingredient: azadirachtin, pyrethrins
  EPA registration number: 1021-1872
• This list may not include all products registered for this use.