Cherry blackfly

Distorted foliage on cherries is unsightly on ornamental trees but does not stop cherry trees from flowering or bearing fruit.

Cherry blackfly (Myzus cerasi) on Cherry (Prunus sp.). Credit: RHS/Entomology.

Quick facts

Common name Cherry blackfly
Scientific name Myzus cerasi
Plants affected Fruiting cherries and ornamental forms of Prunus cerasus, P. avium and P. padus
Main symptoms Curled and distorted leaves at tips, with black aphids present
Most active May–July

What is cherry blackfly?

Cherry blackfly is an aphid that sucks sap from the foliage of fruiting cherries and ornamental forms of Prunus cerasus, P. avium and P. padus during late spring and early summer.

Symptoms

  • During late spring and early summer, the undersides of the leaves and the shoot tips are covered with shiny black aphids
  • Leaves become severely crumpled and curled
  • Later in summer the damaged leaves may dry up and turn brown
  • Foliage becomes sticky with the sugary honeydew that aphids excrete, and a black sooty mould may develop
  • Susceptible types of cherry will survive aphid damage, but they are likely to suffer from curled leaves in most years

Control

Non-chemical control

  • Where an ornamental, rather than a fruiting cherry is required, the problem can be avoided by growing the less-susceptible Japanese types of flowering cherries

Chemical control

  • Treatment is only feasible on trees small enough to be sprayed thoroughly.
  • Such trees can be sprayed with plant oil winter tree wash (e.g. Growing Success Winter Tree Wash or Vitax Winter Tree Wash) in December to reduce the number of overwintering eggs
  • Susceptible ornamental cherries can be sprayed with thiacloprid (e.g. Provado Ultimate Bug Killer) or acetamiprid (e.g. Bug Clear Ultra) in late spring, when aphids begin to appear on the foliage
  • Fruiting cherries can be sprayed with organic pesticides, such as pyrethrum (e.g. Py Spray Garden Insect Killer or Bug Clear Gun for Fruit & Veg), or synthetic contact sprays deltamethrin (Bayer Provado Ultimate Fruit & Vegetable Bug Killer), lambda-cyhalothrin (Westland Resolva Bug Killer). These contact sprays will give poor results once the aphids have caused the leaves to curl. Systemic insecticides, such as thiacloprid (e.g. Provado Ultimate Bug Killer Ready To Use), are absorbed into the foliage and may reach concealed aphids when they feed
  • The manufactures instructions for pesticides must be followed when applied to fruiting trees.
  • Once the leaves have become curled the damage is done and it is too late for effective spraying
  • Do not spray during the open blossom period due to the danger to bees and other pollinating insects

Download

Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)

Biology

  • Cherry blackfly overwinters on the tree as eggs, from which wingless aphids hatch in spring as the foliage develops
  • Winged forms appear in June-July, and these migrate to wild flowers known as bedstraws, Galium species
  • Infestations on cherries gradually die out during July, but damaged leaves remain visible for the rest of the summer
  • There is a return migration from bedstraws in the autumn, when the winter eggs are laid

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