Spur blight

Spur blight is a widespread fungal disease caused by the pathogen Didymella applanata. It primarily affects red raspberries, posing a serious threat to the vitality of the canes and the overall yield of the plantation by interfering with the plant's vascular development.

The characteristic symptoms appear on current-season canes during late summer. Dark brown or purple-colored lesions form around the leaf buds. As the infection progresses, these spots enlarge and can girdle the stem, causing the bark to crack and peel, which makes the canes susceptible to winter injury and desiccation.

The development of the fungus is highly dependent on environmental conditions, particularly moisture. Rainy weather and high humidity favor the release and spread of spores. Poor air circulation in overcrowded plantings exacerbates the problem, allowing the pathogen to thrive and spread rapidly throughout the patch.

The economic impact of spur blight is significant due to the reduction in cane vigor and fruit production. Infected canes often fail to survive the winter, leading to reduced yields in the following season. Additionally, weakened canes are more prone to secondary infections from other pests and pathogens.

Effective management requires a combination of sanitation and chemical interventions. Key practices include:

• Pruning and removing infected canes immediately after harvest to reduce inoculum.
• Maintaining proper plant spacing to ensure adequate air circulation and sunlight penetration.
• Applying registered fungicides during the vegetative growth stage and following the harvesting period.
• Prioritizing the cultivation of disease-resistant varieties and ensuring proper site drainage.