Fruit aphids

Most of fruit grown in gardens can be attacked by sap sucking aphids (commonly known as greenfly, blackfly or plant lice) during spring and summer. These may reduce the plant's vigour and spread viruses.

Aphid damage on fruit tree shoot

Quick facts

Common name Fruit aphids (various species)
Plants affected Most fruits
Main symptoms Distorted growth, honeydew and sooty mould
Caused by Sap sucking insects 
Timing Winter, spring and summer

What are fruit aphids?

Aphids are sap sucking true bugs often called blackfly, greenfly or plant lice. There are more than 500 species found in the UK. Most of the fruits grown in gardens can be affected by at least one species of aphid.

Many of the aphids attacking fruits have similar life cycles. They often overwinter on the trees and bushes as eggs which are laid in crevices in the bark or near the buds. Aphid eggs are shiny black, about 1mm long and ovoid in shape. They hatch in the spring as the buds begin to open and the nymphs feed on the new leaves. Aphids reproduce rapidly and their numbers reach a peak on the fruit host during late spring to early summer.

Winged aphids then develop and migrate away from the fruit tree or bush, sometimes leading to the infestation dying out completely. The aphids spend the summer on herbaceous plants until the autumn, when more winged aphids are produced which fly back to the fruit tree winter host to lay eggs. The summer host is often a wild plant and, since the aphids disperse so widely when they migrate, it is not possible to control them by spraying or removing the summer host.

Some aphids, for example woolly aphid, and brown peach aphid, do not have a wild summer host and instead remain on fruit trees throughout the year.

Summer hosts and migration periods of some common fruit aphids

Apple

  • Rosy apple aphid: Summer host = plantains (Plantago spp.). Leaves fruit in June-July
  • Apple-grass aphid: Summer host = annual meadow grass (Poa annua). Leaves fruit inMay
  • Rosy leaf-curling aphid: No migration
  • Woolly aphid: No migration

Cherry

  • Cherry blackfly: Summer host = bedstraws (Galium spp.). Leaves fruit in June-July

Peach

  • Peach-leaf rolling aphid: Summer host = clematis. Leaves fruit in May-June
  • Brown peach aphid: No migration

Pear

Plum

  • Plum leaf-curling aphid: Summer host = many herbaceous plants. Leaves fruit in May-early June
  • Mealy plum aphid: Summer host = grasses and reeds. Leaves fruit in June-July. Can remain on plum throughout summer

Currants

Gooseberry

  • Lettuce aphid: Summer host = lettuce. Leaves fruit in May-June
  • Gooseberry aphid: Summer host = willow herbs (Epilobium spp.). Leaves fruit in May-June. Can remain on gooseberry throughout summer

Blackberry

  • Blackberry aphid: Summer host = grasses. Leaves fruit in May-June

Raspberry

Strawberry

  • Strawberry aphid: No migration

Symptoms

Fruit aphids can reduce the plant's vigour and affect yield by sucking sap from leaves, stems and sometimes the fruits of trees.

Many aphids also have substances in their saliva that cause a variety of symptoms, such as stunted growth, leaf curling, distorted fruits and discoloration of the foliage.

Some virus diseases, especially of soft fruits (e.g. raspberry viruses and strawberry viruses), can be transmitted by aphids as they move from one plant to another. Infected plants may show stunted growth, leaf mottling or other symptons.

Aphids excrete a sugary substance, known as honeydew that makes the foliage and fruits sticky and can attract ants.  A black sooty mould often grows on the honeydew, especially in wet summers, which reduces the amount of sunlight reaching the leaves and can spoil the appearance of the fruit.

Control

Fruit aphid infestations are often not noticed until the plants are showing obvious signs of damage in the spring and early summer. In some cases by this time the damage is done and the aphids may have already left for their summer hosts making control measures redundant.

Natural enemies

In some years populations of these natural enemies can keep aphid numbers in check. Aphids have many natural enemies including ladybirds, hoverfly larvae, lacewing larvae and parasitic wasps. Earwigs have also been shown to reduce aphid infestations on apple trees and potentially other tree fruits.

Indiscriminate use of pesticides can reduce the numbers of these useful predators. 

Chemical control

  • Early control measures are necessary if damage is to be prevented
  • On plants small enough to be sprayed thoroughly, some overwintering eggs can be destroyed by using a plant oil winter wash (organic e.g. Vitax Winter Tree Wash) when the buds are fully dormant in November-early February on a dry frost-free day. This is recommended when fruit aphids has been a problem in previous years. Plant oil winter washes are likely to be least detrimental to natural enemy populations and also can mean that spring sprays are unnecessary
  • In the spring pesticides (including organic types) can be applied to control aphids that have hatched, provided the crop plant is listed on the label and the manufactures instructions are followed. As with winter wash only plants small enough to be sprayed can be treated
  • Plants in flower should not be sprayed due to the danger to pollinating insects. All fruits are insect pollinated
  • If spraying is considered necessary and practical the best time to spray apple, cherry, plum, currants, gooseberry and raspberry is when the blossom buds are visible, but before they open. Spray pear and peach when flowering has finished. Further applications can be given if aphids appear later in the season.
  • Sprays are less likely to be successful once leaf distortion has occurred
  • Check the labels before use but in general the synthetic pyrethroid insecticide deltamethrin can be used on all fruits listed above except gooseberry, red currant and peach; the pyrethroid lambda-cyhalothrin on all except peach. Pyrethrum (considered organic) can be used on all fruits but, being less persistent, requires very thorough application. The insecticides listed above are contact in action and will give poor control of aphids concealed by curled leaves. 
  • Acetamiprid is systemic neonicotinoid insecticide and may control aphids in curled leaves, it can be used on  apple, pear, cherry and plum.

Some pesticide active ingredients and brand names:

  • Plant oil winter washes (Considered organic, e.g. Vitax Winter Tree Wash)
  • Deltamethrin (e.g. Bayer Provado Ultimate Fruit & Vegetable Bug Killer,  Bayer Sprayday Greenfly Killer)
  • Lambda-cyhalothrin (e.g. Westland Resolva Bug Killer)
  • Pyrethrum (Considered organic, e.g. Bug Clear Gun for Fruit & Veg, Defenders Bug Killer, Pyrol Bug & Larvae Killer, ecofective Bug Killer (also contains fatty acids)
  • Acetamiprid (systemic e.g. Bug Clear Ultra), can be used on apple, pear, cherry and plum

Note: There are limitations on the products that can be used on food plants always check that the food plant is listed on the label and follow the manufactures instructions regarding harvest interval and maximum number of applications for the fruit concerned.

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

Downloads

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

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