Three aphid (blackfly/greenfly) species feed on currants and can cause distortion to leaves, the currant-sowthistle aphid, currant blister aphid and permanent currant aphid.
Scientific names: Hypermyzus lactucae, Cryptomyzus ribis and Aphis schneideri
Plants affected: Currants
Main symptoms: Distorted and discoloured leaves
Most active: Spring and summer
What are currant aphids?
Three aphid (greenfly/blackfly) species are common on currants. All three species overwinter on the stems as eggs that hatch in the spring. Only the currant-sowthistle aphid may affect cropping and these aphids can often be tolerated as part of garden biodiversity.
- The currant-sowthistle aphid (Hypermyzus lactucae), which in late spring, causes distorted leaves with yellowish mottling, this is the only currant aphid which may affect cropping
- Currant blister aphid (Cryptomyzus ribis) causes puckered, reddish or yellowish leaves at the shoot tips. Cropping usually remains unaffected
- Permanent currant aphid (Aphis schneideri) is black and remains on currants throughout the summer. It causes pronounced stunting of the shoot tips with the leaves compressed together. This species does not normally affect the crop
Check currants frequently from spring onwards so action can be taken before a damaging population has developed. When choosing control options you can minimise harm to non-target animals by starting with the methods in the non-pesticide control section. If this is not sufficient to reduce damage to acceptable levels then you may choose to use pesticides. Within this group the shorter persistence pesticides (that are usually certified for organic growing) are likely to be less damaging to non-target wildlife than those with longer persistence and/or systemic action.
- Where possible tolerate populations of aphids. Some damage from these aphids can be tolerated with no effects on quality or quantity of yield. Aphids form an important part of many food chains and can be part of a healthy garden ecosystem
- Use finger and thumb to squash aphid colonies where practical
- Encourage aphid predators in the garden, such as ladybirds, ground beetles, hoverflies, parasitoid wasps and earwigs. Be aware that in spring aphid populations often build up before natural enemies are active in sufficient numbers and then give good control
Pesticide controlThe RHS believes that avoiding pests, diseases and weeds by good practice in cultivation methods, cultivar selection, garden hygiene and encouraging or introducing natural enemies, should be the first line of control. If chemical controls are used, they should be used only in a minimal and highly targeted manner.
- There is no point in spraying after the foliage has become distorted
- On fruit trees and shrubs. Overwintering aphid eggs can be destroyed by using a plant oil winter wash (organic e.g. Vitax Winter Tree Wash). This can be used when the buds are fully dormant in November-early February on a dry frost-free day. Plant oil winter washes are less likely to be detrimental to natural enemies and can mean that spring sprays are unnecessary
- Organic sprays, such as natural pyrethrum (e.g. Bug Clear Gun for Fruit & Veg, Neudorff Bug Free Bug and Larvae Killer), fatty acids (e.g. Doff Greenfly & Blackfly Killer) or plant oils (e.g. Vitax Plant Guard Pest & Disease Control, Bug Clear for Fruit and Veg) can give good control of aphids. These pesticides have a very short persistence and so may require reapplication to keep aphid numbers in check. Plant oil and fatty acid products are less likely to affect larger insects such as ladybird adults
- Plant invigorators combine nutrients to stimulate plant growth with surfactants or fatty acids that have a physical mode of action against aphids (e.g. Ecofective Bug Control, RHS Bug and Mildew Control, SB Plant Invigorator and Westland Resolva Natural Power Bug & Mildew). These products contain some synthetic ingredients and so are not considered organic
- More persistent contact-action insecticides include the synthetic pyrethroids lambda-cyhalothrin (e.g. Westland Resolva Bug Killer), deltamethrin (e.g. Provanto Ultimate Fruit & Vegetable Bug Killer, Provanto Sprayday Greenfly Killer) and cypermethrin (e.g. Py Bug Killer)
- A systemic containing the active ingredient Flupyradifurone (Provanto Smart Bug Killer) is available for use on ornamentals and selected edibles
On edible plants make sure the food plant is listed on the label and follow instructions on maximum number of applications, spray interval and harvest interval.
Plants in flower should not be sprayed due to the danger to bees and other pollinating insects
Inclusion of a pesticide product does not indicate a recommendation or endorsement by RHS Gardening Advice. It is a list of products currently available to the home gardener
Pesticides for gardeners (pdf document)
Currant-sowthistle aphid (Hypermyzus lactucae) is up to 2.7mm long and green, with pale legs. The eggs hatch in March or April. By May large colonies of aphids can develop on currants. Currant-sowthistle aphid colonies die out on currants during May and June and winged forms migrate to the summer host sowthistle (Sonchus spp.) where they form colonies during the summer months. In the autumn there is a return migration to currants where mating occurs and overwintering eggs are laid in the bud axils.
Currant blister aphid (Cryptomyzus ribis) are pale yellow and live on the underside of the leaves where they feed by sucking sap. Where they feed a puckering, distortion and reddish discolouration often develops. Wingless forms of the blister aphid are active on currants from bud burst until July. In midsummer, winged aphids develop and migrate to the wild flower known as hedge woundwort (Stachys sylvatica). Populations on currants come to an end at that time, although damaged foliage remains visible until leaf fall. Aphids return to currants in the autumn when overwintering eggs are laid.
Permanent currant aphid (Aphis schneideri) reaches 2.2mm in length and is black. Eggs hatch in spring and colonies soon develop on shot tips. As the common name suggests this aphid can be present on currants all year although winged forms are produced in the summer these migrate to other currants.
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