Cane spot (Elsinoe veneta)
This fungal disease can be a serious problem in raspberries, hybrid berries and blackberries. Spots first appear in May and June then travel up the plant. The purple spots grow like fairy rings, leaving dead cells in a depression as they expand. Infections which overwinter on last years' canes will infect the following year's new growth unless checked.
- Purple spots on lower parts of stems
- Spots grow and spread upwards, leaving silvery-white depressions with purple margins - typically elliptical on stems and circular on leaves.
- Leaves and fruit may be distorted and leaves may die back
- In severe cases, plant may die
Prevention & control
- Grow resistant varieties
- Good rotation - plants new canes on another part of your plot
- Remove and burn infected canes in the autumn to prevent overwintering and infection of next year's new growth
- If it becomes a problem, you can spray with Bordeaux mixture (copper/quicklime) at fortnighly intervals from when the leaf buds first open to when the first petals fall