Leaf And Cane Spot
[VERIFY]
5 host plants
Last updated
Watch for small dark lesions that start on canes and leaves of your raspberries and blackberries, particularly during wet springs. The spots develop as the season progresses, eventually coalescing on foliage and cane tissue. In severe infections, leaf loss happens earlier than normal, sometimes dramatically stripping plants before mid-summer. This timing of symptom development makes identification straightforward once you know what you're looking for.
The significance here isn't just aesthetics; premature defoliation weakens canes before winter, reducing hardiness and fruiting potential for the following year. Dense, vigorous growth accelerates this disease since the fungus thrives in the humid microclimate that excessive foliage creates. The one management principle that matters most: prune and space aggressively to allow air flow through the fruiting canes, skip overhead watering, and clean up all debris after harvest without composting it.
Quick Reference
Management
Severe leaf infections can cause premature loss of leaves, sometimes resulting in considerable leaf
Cultural Controls
- Space plantings, prune, and train to provide good air circulation and reduce humidity.
- Avoid overhead watering.
- Provide proper culture.
- Excess fertilizer promotes dense, slow-drying, easily infected foliage.
- Clean up all plant debris.
- Destroy or discard (do not compost) diseased materials.