Cherry blackfly

Cherry blackfly can cause distorted foliage on cherries, this is unsightly 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
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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, causing tight leaf curling.

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 can suffer from curled leaves in most years

Control

Non-chemical

  • 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

  • Treatment is only feasible on trees small enough to be sprayed thoroughly
  • Small trees can be sprayed with plant oil winter tree wash (e.g. Growing Success Winter Tree Wash) in December to reduce the number of overwintering eggs
  • In spring once the leaves have become curled the damage is done and it is usually too late for effective spraying
  • Ornamental and fruiting cherries can be sprayed with organic pesticides, such as pyrethrum (e.g. Bug Clear Gun for Fruit & Veg or Pyrol Bug & Larvae Killer Concentrate), or synthetic contact sprays deltamethrin (e.g. Bayer Provado Ultimate Fruit & Vegetable Bug Killer), lambda-cyhalothrin (e.g. Westland Resolva Bug Killer). These contact sprays will give poor results once the aphids have caused the leaves to curl. Systemic insecticides, such as the neonicotinoid acetamiprid (e.g. Bug Clear Ultra), 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, including maximum number of applications and harvest interval
  • Do not spray during the open blossoms due to the danger to bees and other pollinating insects
  • Inclusion of a pesticide product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener

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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