Problem type: Disease
Name of problem: Raspberry cane blight
Plant name(s): Raspberry (black, red and purple) and blackberry
Symptoms / Characteristics:
Symptoms are typically associated with wounded tissue. Discolouration originates at the wound sites and the canes become dark brown. Black fungal bodies are visible on infected areas and the bark may be covered in a grey dust. Canes are weakened and often break at the point of infection. Wilting of subsequent shoots and laterals occurs in the next growing season.
Raspberry cane blight is a fungal disease caused by Leptosphaeria coniothyrium. Cane blight and spur blight often occur simultaneously, making diagnosis difficult. Raspberry spur blight is caused by a different fungus (Didymella applanata) and, although the symptoms differ, the control methods are similar.
Control / Preventions:
Avoid wounding the canes during pruning and harvesting. Restrict pruning to periods of dry weather. Remove and destroy infected canes throughout the growing season and remove fruiting canes after harvest. Promoting good air circulation reduces disease incidence. This involves regular weeding, pruning, thinning and the removal of fruited canes. Avoid dense plantings and excess irrigation, as warm and wet conditions favour the development and spread of the disease. Water at the soil surface instead of using overhead irrigation. Implement a balanced fertilizer program. Excess nitrogen leads to rapid growth of vulnerable succulent tissue that is ideal for fungal invasion. A lime sulphur fungicide can be used as a chemical control