WSU Extension

Hortsense

Plum, Prune (Fresh)
 
Disease
Armillaria root rot 
Bacterial canker 
Black knot 
Brown rot 
Crown gall 
Cytospora canker 
Plum pockets 
Russeting 
Shothole (Coryneum blight) 
Silver leaf 
Virus diseases 
Insect
Aphids 
Apple-and-thorn skeletonizer 
Brown marmorated stink bug 
Earwigs 
Fruittree leafroller 
Leafhoppers 
Pacific flatheaded borer 
Peach twig borer 
Peachtree borer 
Pear slug 
Scale insects 
Shothole borer 
Spider mites 
Spotted wing Drosophila (SWD) 



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Caption: Leaf curl plum aphid
Photo by: A.L. Antonelli
  
Plum, Prune (Fresh) : Aphids
(revision date: 4/11/2018)


Biology
Several aphid species can be found on plums, including the hop aphid and the leafcurl plum aphid. The hop aphid is yellowish to dark green. The leafcurl plum aphid is dark green to reddish in early spring and fall, and pale green in the summer. Aphids typically feed in colonies on the tips of new growth and the undersides of leaves. Infested leaves and shoots are curled and distorted. Feeding aphids produce large amounts of honeydew, a sweet, sticky material which may attract ants or become covered with a dark growth of sooty mold. Honeydew and sooty mold can reduce fruit quality.
Management Options

Non-Chemical Management
  • Encourage natural predators including ladybird beetles, lacewings, syrphid flies, and parasitic wasps. Avoid use of broad-spectrum insecticides which kill beneficial insects.
  • Hand-wipe or prune to control small, localized infestations when practical.
  • Wash aphids from trees with a strong stream of water before leaves curl.
  • Control honeydew-feeding ants, which may protect aphid colonies from predators.
  • Provide proper nutrition. High levels of nitrogen encourage aphid reproduction. Switch to a slow-release or low-nitrogen fertilizer.
Select non-chemical management options as your first choice!

Chemical Management

Apply superior type oils to manage overwintering aphid eggs. Use as needed through the growing season. Thorough coverage of the foliage is important, including lower leaf surfaces. Insecticidal soaps usually require multiple applications. 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.

Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
  • All Seasons Horticultural & Dormant Spray Oil Conc [Organic]
    Active ingredient: oil/pet distillate  |  EPA reg no: 4-80
  • Azamax Botanical Insecticide, Miticide, & Nematicide [Organic]
    Active ingredient: azadirachtin  |  EPA reg no: 71908-1-81268
  • Ortho Volck Oil Spray Dormant Season Insect Killer Conc
    Active ingredient: oil/pet distillate  |  EPA reg no: 239-16
  • R-T-U Year-Round Spray Oil
    Active ingredient: oil/pet distillate  |  EPA reg no: 6218-78
  • Safer Brand BioNEEM Multi-Purpose Insecticide & Repellent Conc [Organic]
    Active ingredient: azadirachtin  |  EPA reg no: 70051-6-42697
  • Safer Brand Garden Defense Multi-Purpose Spray Conc [Organic]
    Active ingredient: clarified hydrophobic extract of neem oil  |  EPA reg no: 70051-2-42697
  • Safer Brand Insect Killing Soap Conc II [Organic]
    Active ingredient: potassium laurate  |  EPA reg no: 42697-60
  • This list may not include all products registered for this use.
Images

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Caption: Leaf curl plum aphid
Photo by: A.L. Antonelli
Caption: Aphid colony
Photo by: A.L. Antonelli
Caption: Aphid cast skins
Photo by: R.S. Byther