Why Are My Raspberry Leaves Curling?

Raspberry leaf curl virus

Raspberry leaf curl virus (RLCV) is the most serious cause of curling raspberry leaves in the UK. It is transmitted between plants by the large raspberry aphid (Amphorophora idaei), which acquires the virus from infected plants and spreads it to healthy ones as it feeds. RLCV infection causes the leaves to curl downward and cup, developing a puckered, crinkled, blistered surface texture that persists throughout the growing season. Unlike simple aphid damage (which typically affects only the soft growing tips and resolves as the aphid colony is controlled), RLCV affects leaves across the entire plant progressively and worsens year by year. Infected plants also produce small, seedy, crumbly, dry fruits of poor quality. There is no cure for RLCV once a plant is infected.

What to do

• If RLCV is suspected, confirm by observing whether the curling and leaf distortion affects only the growing tips (more likely aphids) or is widespread across the cane and persistent through the season (more likely virus). Checking the fruit quality provides additional evidence: RLCV significantly reduces fruit size and flavour.
• Remove and destroy all canes from infected plants immediately. Do not compost; burn if possible or place in council green waste. Remove the entire stool (root system) if practical to prevent re-shooting from the roots.
• Do not replant raspberries in the same ground for at least 3 years to reduce the risk of virus persisting in root fragments and re-infecting new plants.
• When replanting, choose certified virus-free canes from a reputable supplier and select aphid-resistant varieties: many modern raspberry varieties carry the A10 gene for resistance to the large raspberry aphid, which is the primary RLCV vector. Popular aphid-resistant varieties include 'Glen Ample', 'Glen Lyon', 'Glen Moy', and 'Tulameen'.

Aphids

Several aphid species attack raspberries in the UK. The large raspberry aphid (Amphorophora idaei) is the primary RLCV vector and feeds on young cane growth. The small raspberry aphid (Aphis idaei) colonies on the growing tips cause the young leaves to curl tightly around the feeding insects. Aphid damage without virus is typically confined to the growing tips and soft new growth, resolves as natural predators arrive, and does not significantly affect fruit quality.

What to do

• Inspect raspberry cane tips from April. Small aphid colonies can be removed by hand or with a jet of water. On healthy, virus-free plants, encouraging natural predators (ladybirds, hoverflies, parasitoid wasps) is the most sustainable long-term control.
• Growing aphid-resistant raspberry varieties substantially reduces both aphid infestation and the risk of RLCV transmission.
• If aphids are persistent, an insecticidal soap spray applied to the underside of leaves and growing tips in spring, before natural predators arrive in significant numbers, can reduce the population early in the season.

Cane blight

Cane blight (Leptosphaeria coniothyrium) is a fungal disease that infects raspberry canes, usually through wounds, pruning cuts, or insect damage. Infected canes develop a dark, cracked area at the base. The leaves on infected canes wilt rapidly and curl, turning brown while still on the cane. The entire cane collapses and dies within a few weeks of infection appearing.

What to do

• Remove and destroy affected canes at the first sign of the dark basal lesion: cut well below the infected area to healthy wood and destroy the removed canes. Sterilise cutting tools between cuts with a dilute bleach solution or methylated spirits.
• Improve airflow through the raspberry row by training and tying in canes carefully and keeping the row to a manageable width. Avoid damaging canes during cultivation and pest control operations, as wounds are the primary entry points for the blight fungus.

Drought

Drought causes raspberry leaves to curl upward at the edges and develop a dull, greyish-green appearance. The canes are relatively shallow-rooted and are susceptible to drought particularly during fruit development, when water stress significantly reduces yield and fruit size.

What to do

• Apply a thick (8 to 10 centimetre) mulch of compost, bark, or straw along the raspberry row to conserve soil moisture. Water during dry spells, particularly from flowering through to harvest: irrigation at this stage has the greatest impact on fruit quality and yield.

Frequently asked questions

Why are my raspberry leaves curling?

Raspberry leaves curl most commonly because of raspberry leaf curl virus (RLCV), aphid feeding, or raspberry cane blight. Raspberry leaf curl virus is a serious and incurable disease transmitted by the large raspberry aphid (Amphorophora idaei). Infected plants develop downward-curled, cupped, and puckered leaves that become increasingly crinkled and distorted as the infection progresses. The fruits become small, seedy, and crumbly. There is no cure; infected canes must be removed and destroyed. Aphids alone (without virus) cause the growing tips to curl around the feeding colonies in spring. Cane blight (Leptosphaeria coniothyrium) causes the leaves on affected canes to wilt and curl as the cane dies back from a fungal infection at the base.

How do I know if my raspberry has leaf curl virus?

Raspberry leaf curl virus (RLCV) has a distinctive set of symptoms that distinguish it from simple aphid damage or other causes of curling. Look for: leaves that curl downward and cup persistently throughout the season (not just the growing tips); a puckered, blistered, or crinkled texture to the leaf surface; leaves that are darker green or duller than healthy leaves; stunted, bushy growth with shortened internodes; and, most definitively, fruits that are small, seedy, crumbly, and dry rather than plump and juicy. RLCV symptoms worsen over successive seasons. If only the very tip of the cane shows curled leaves in spring but the rest of the plant looks normal and produces good fruit, aphid feeding rather than virus is the likely cause.

Can I eat raspberries from a plant with leaf curl virus?

The fruits from raspberry plants with leaf curl virus are safe to eat but are often of very poor quality: small, seedy, crumbly, and lacking the juicy sweetness of fruits from healthy canes. In the early stages of infection, the impact on fruit quality may be minor, but as the disease progresses over successive seasons the fruits become increasingly worthless. More importantly, the infected plant acts as a permanent reservoir of the virus, which can be spread to neighbouring healthy raspberry plants by the raspberry aphid. For this reason, once raspberry leaf curl virus is confirmed, the affected plant should be removed and destroyed even if it is still producing some fruit: the risk to nearby healthy plants outweighs the small harvest from the infected canes.

How do I prevent raspberry leaf curl virus?

Preventing raspberry leaf curl virus (RLCV) relies on preventing the large raspberry aphid (Amphorophora idaei) that transmits it, and on starting with certified virus-free planting material. Key measures: always buy raspberry canes certified as virus-free from a reputable supplier, not from gardens where the virus history is unknown; grow aphid-resistant raspberry varieties (many modern varieties bred for aphid resistance carry a gene for resistance to the large raspberry aphid, removing the primary RLCV vector); remove and destroy any canes showing RLCV symptoms immediately to prevent spread; control aphid populations by maintaining good populations of beneficial insects (ladybirds, hoverflies, parasitoid wasps) and avoiding broad-spectrum insecticides that kill predators as well as pests; and inspect new plantings regularly in spring, when aphid populations build and migration from overwintering sites onto raspberry canes first occurs.