Raspberry cane blight

What you see

Canes that fruited well suddenly wilt, the leaves wither, and the cane snaps easily at the base. Dark patches with a silvery-purple sheen appear near ground level, and the bark cracks and peels.

Conditions

Enters through wounds - cane midge damage, pruning cuts, string ties, wind rub. Wet summers and damaged canes together are what triggers it.

Treatment

Cut affected canes right out at ground level and burn or bin them. Disinfect secateurs between cuts. Do not leave stubs.

Prevention

Handle canes gently and avoid wounding them. Control cane midge. Thin canes for airflow, tie carefully with soft ties, and prune only in dry weather.

Months: June, July, August, September

Plants

Raspberry, Blackberry

Remedies

Bordeaux mixture (copper)

The thing people get wrong

This is a wound disease, so the answer is in how you handle the plant, not in a bottle. The two habits that cause most of it are pruning wet and tying canes tight with wire or plastic string, which rubs a doorway through the bark all summer. Soft ties and dry secateurs prevent most cases outright.