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Aphids are sap

Sap is a fluid that circulates through a plant's vascular system, in a similar way to blood moving through our veins. Phloem sap carries the sugars produced in the leaves by photosynthesis down to roots and other storage organs, as well as carrying minerals and hormones. Xylem sap is watery and transports nutrients absorbed by the roots upwards to the rest of the plant. Some plants leak sap from wounds or pruning cuts, and this is known as bleeding. -sucking true bugs. They range in size from 1 to 7 mm (¼ in or less) long. Some aphids are known as greenfly or blackfly, but there are species that are yellow, pink, white or mottled. There are more than 500 aphid species in Britain. Some feed on only one or two plant species, but others can be found on a wide range of plant hosts. Many have lifecycles that involve more than one host plant. Almost any plant can be a host to aphids, including ornamentals, vegetables, fruits, greenhouse plants and houseplants. More information on aphids .

Currant blister aphid is one of a number of aphids that feed on currants . Is pale yellow and up to 2.5 mm in length. It can be found on 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 discolouration
• Pale yellow aphids can be found underneath the blistered areas in late spring-early summer
• This aphid is a food source for many aphid predators and colonies can be wiped out

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

Aphids form the basis of many food chains and it is not unusual to have some of these animals in a healthy balanced garden ecosystem. On established bushes aphids can usually be considered part of the biodiversity

The variety of living organisms (plants, animals, fungi and microorganisms) in a particular environment. Boosting the biodiversity of your garden has many benefits, including supporting wildlife, improving soil health and reducing the likelihood of pest and disease problems. they support, natural enemies will normally reduce numbers during summer.

• Some damage from these aphids can be tolerated with no effects on quality or quantity of yield.
• 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
• Check currants frequently from spring onwards so action can be taken before a damaging population has developed
• Use finger and thumb to squash aphid colonies where practical

Currant blister aphids are pale yellow and live on the underside of the leaves where they feed by sucking sap

Sap is a fluid that circulates through a plant's vascular system, in a similar way to blood moving through our veins. Phloem sap carries the sugars produced in the leaves by photosynthesis down to roots and other storage organs, as well as carrying minerals and hormones. Xylem sap is watery and transports nutrients absorbed by the roots upwards to the rest of the plant. Some plants leak sap from wounds or pruning cuts, and this is known as bleeding. . Whilst they feed, 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

A bud is a small, undeveloped shoot that contains the potential for new growth. Buds are typically found on stems, where they can be apical (found at the tip) or axillary (found between leaf axils) and may develop into leaves, shoots or flowers. burst until July. After this, round 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. The aphids return to currants in the autumn when overwintering eggs are laid.