How Do I Treat My Rose Problem?

Anne Swithinbank’s masterclass on: rose problems

- Anne Swithinbank

Q Some of my roses have rolled leaves, making them look rather odd. Could this explain why they have not grown and flowered well this year? Mags Penwick, Burnaston, Derbyshire

A From April to June, the tiny adults of rose leaf-rolling sawfly hatch from pupae in the soil and the females insert their eggs into rose leaflets. At the same time, they secrete a chemical causing leaves to dip down and curl inwards along their length.

Protected within these green tubes, the caterpillar-like larvae feed safely. Occasionally a leaflet is probed and no egg laid but the leaves roll anyway. By July, the larvae have left the rose and enter soil to overwinter as dormant larvae, ready to pupate in spring and hatch to repeat the life cycle.

Sawfly damage is usually light, superficial and unlikely to affect the health of plants. We are often advised to pick rolled leaves off but I leave them, on the basis that they are still photosynthesising and feeding the plants. If there are only a few, it is possible to find and destroy the larvae inside. However, I doubt that the rolled leaves are to blame for the poor performance of your plants.