Currant blister aphid

Currant blister aphid is one of a number of aphids that attack currants. It is a sap-sucking insect that infests the lower leaf surface in early summer and causes leaf distortion.

• Leaves at the shoot tips appear puckered or blistered
• The distorted foliage takes on a reddish or yellowish green discoloration
• Pale yellow aphids can be found underneath the blistered areas in late spring-early summer

Currants affected by blister aphid still make growth and produce a good crop, so treatment is not essential.

Non-pesticide control

• Where possible tolerate infestations of currant blister aphid, this aphid does not usually affect plant vigour or cropping
• ​Aphids have many natural enemies, including ladybirds, hoverfly larvae, lacewing larvae and several parasitoid wasps. In spring damaging aphid infestations often build before natural enemies are active in sufficient numbers to give good control
• Use finger and thumb to squash infestations on small plants

Pesticide control

• Organic sprays, such as natural pyrethrum (e.g. Bug Clear Gun for Fruit & Veg, Ecofective Bug Killer), fatty acids (e.g. Solabiol Bug Free, Doff Greenfly & Blackfly Killer) or plant oils (e.g. Vitax Organic 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
• More persistent insecticides include the synthetic pyrethroids lambda-cyhalothrin (e.g. Westland Resolva Pest Killer), deltamethrin (e.g. Provanto Ultimate Fruit & Vegetable Bug Killer) and cypermethrin (e.g. Py Bug Killer)
• Follow label instructions when using pesticides. On edible plants make sure the food plant is listed on the label and follow instructions on maximum number 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 the RHS. It is a list of products currently available to the home gardener

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

• Currant blister aphids are pale yellow and live on the underside of the leaves where they feed by sucking sap
• They also secrete chemicals into the foliage and this causes puckering, distortion and discolouration
• Other species of aphid also occur on currants but they do not produce this characteristic blistering symptom. 
• 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)
• Infestations on currants come to an end at that time, although damaged foliage remains visible until leaf fall
• The aphids return to currants in the autumn when overwintering eggs are laid

Aphids
Aphid predators
Blackcurrants
Blackcurrant big bud mite
Blackcurrant gall midge
Chemical labels explained
Chemicals: using a sprayer
Chemicals: using safely and effectively
Conifer aphids
Currant and gooseberry leaf spot
Currant aphids
Cypress aphid
Fruit aphids
Green spruce aphid
Gooseberries, red and white currants
Harlequin ladybird
Hedgerow fruit
Hellebore aphids
Ladybirds
Lupin aphid
Mealy cabbage aphid
Pear bedstraw aphid
Plum aphids
Privet aphid
Raspberry and blackberry aphids
Rose aphids
Rose root aphid
Rosy apple aphid
Willow bark aphid
Woolly aphid
Woolly beech aphid
Woolly vine or currant scale