Why Are My Blackberry Leaves Curling?

Blackberry leaves curl for several different reasons, and distinguishing between them guides the response. The most common cause is aphid feeding on young shoot tips in spring, which causes the leaf to roll downward and inward at the edges. Drought stress in summer causes a different type of curling — the leaf edges curl upward and inward as a water-conservation response. Virus infection causes a more persistent downward rolling or crinkling that does not resolve when conditions improve.

Aphid-caused leaf curl

Rubus aphid and black bean aphid colonies feed on young shoot tips in April and May. Their feeding causes the leaf to roll inward, enclosing the colony inside the curl and providing a sheltered feeding site. Uncurl the leaf gently and you will see the insects inside. Squeezing the colony between finger and thumb or spraying with insecticidal soap directly into the curl is effective. The leaf will not un-curl once the aphids are removed — but new healthy growth above the affected tips will be normal.

Drought stress curling

In dry spells from June onward, established blackberry plants experiencing moisture stress will curl leaves upward — the leaf edges and centre ridge curl inward to reduce the leaf surface area exposed to drying sun and wind. This is a temporary response and reverses quickly after thorough watering. Water deeply at the root zone rather than lightly at the surface — the plant needs moisture reaching the main root mass. Mulching around the base with 5–8 cm of organic material reduces moisture loss significantly.

Virus-related curling

Blackberry is susceptible to several viruses — including blackberry yellow vein disease and raspberry leaf curl virus — transmitted by aphids. Virus-infected plants show persistent leaf curling and rolling, often with yellow mosaic patterns, leaf crinkling, and reduced fruit size, and the symptoms do not improve with watering or aphid control. There is no cure for a virus-infected plant; if virus is confirmed, remove and destroy the plant and replace with certified virus-free stock from a reputable supplier. Plant away from the original site.