Gnomonia cane canker

Gnomonia cane canker, caused by the fungus Gnomonia rubi, is a significant fungal disease affecting raspberry canes. The pathogen colonizes the stems of the plants, often leading to necrosis, structural weakness, and a reduction in the overall vigor of the raspberry bushes.

The primary host for this pathogen is the common raspberry. The infection targets the canes, where it disrupts the vascular system. Because of this, the plant struggles to transport nutrients and water effectively, which leads to diminished yields and the potential death of severely affected stems.

The most visible symptoms include the development of reddish-brown spots on the canes during the growing season. As the fungus matures, these spots enlarge and may encircle the stem. Tiny black dots, known as pycnidia, appear within these lesions, serving as the primary source for further spore dispersal across the field.

Environmental conditions play a critical role in the development and spread of Gnomonia rubi. High humidity, frequent rainfall, and stagnant air in dense, unpruned patches facilitate the germination and movement of spores. The pathogen survives the winter in infected stem tissue, ready to re-emerge when conditions become favorable in the spring.

Effective management requires a proactive approach centered on sanitation and environmental control. Key strategies include:

• Pruning and removing infected canes immediately upon detection.
• Destroying pruned material to remove the source of inoculum.
• Ensuring adequate spacing between rows to promote air circulation.
• Applying fungicide treatments during the pre-bloom and post-harvest stages.