Why Are My Raspberry Shoot Tips Curled and Sticky?

Young raspberry shoot tips that curl inward and feel sticky are infested with raspberry aphids. The tightly-curled leaf clusters at growing points are caused by the mechanical and chemical effect of aphid feeding — the aphids protect themselves inside the curled leaves while feeding on the tender shoot tissue. The sticky feel is honeydew, the sugar-rich excretion produced by aphids as they process plant sap. Raspberries host several aphid species, of which the raspberry aphid (Amphorophora idaei) is the most significant because it transmits viral diseases.

Direct damage from aphids

Mild aphid infestations cause curled shoot tips and stunted growth on affected shoots but are rarely plant-threatening to established canes. The curling itself unrolls as the leaves mature and the plant grows away from the infestation. Large colonies can slow cane growth and reduce vigour if the season is prolonged and the infestation goes unmanaged.

Virus transmission — the main concern

Raspberry aphid is a vector for multiple raspberry viruses including raspberry mosaic virus complex and raspberry leaf curl virus. A single aphid that has fed on a virus-infected plant can transmit the virus to a healthy one in minutes. This is the real reason to manage aphid populations: not the physical feeding damage but the viral legacy that follows. Raspberry viruses cause progressive decline, reduced yield and poor fruit quality for which there is no treatment.

Control methods

Insecticidal soap sprays applied directly to infested shoot tips dislodge and kill aphids. Apply in the evening to minimise impact on pollinating insects. Physical water jets work for light infestations. Encouraging natural predators — ladybirds, lacewing larvae, parasitic wasps — is the best long-term management. Varieties with resistance to raspberry aphid (which confer resistance to the viruses the aphid transmits) are available and worth considering when replanting.