Q How do I recognise raspberry cane blight?

A Cane blight attacks at ground level, but the first symptom you are likely to spot is the shrivelling and dying of leaves on the older, fruiting canes. Look for dark patches on the canes just above soil level. These develop cracks and become covered in black fruiting bodies the size of a pin-head. The canes become brittle and may snap off.

Caption: Raspberry cane blight causes the canes to turn brittle

Q Tell me more about raspberry cane blight.

A The disease is caused by a fungus (Leptosphaeria coniothyrium) which lives in the soil. It enters the base of canes through splits in the bark, often the result of cane-midge attacks.

Q How can I control raspberry cane blight?

A Once spotted, it cannot be treated and should be cut out below ground level and burned. Clean the secateurs with garden disinfectant before pruning any healthy canes.

Q Can raspberry cane blight be prevented?

A The spores survive for several years in the soil, so plant new raspberries elsewhere. Do not plant strawberries in infected ground either as this fungus will attack their roots. Replace the plants with new stock every seven to ten years.