Q How do I recognise it?
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.
Q Tell me more about it.
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 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 it 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.