Botryosphaeria stem canker

Systematic position and pathogen classification: The fungus Botryosphaeria corticis is classified under the kingdom Fungi, phylum Ascomycota, and order Botryosphaeriales. It is a significant plant pathogen known specifically for its role as the causal agent of stem canker in Vaccinium species.

Diseases and host plants: The primary disease associated with this pathogen is known as Blueberry Stem Canker. It specifically affects highbush blueberries. The fungus attacks the bark and cambium of the stems, leading to the development of necrotic lesions that can girdle the stems entirely.

Biology and life cycle: Botryosphaeria corticis survives in the infected stem tissues of the blueberry bushes. During the growing season, the fungus produces spores (conidia and ascospores) which are disseminated by rain splash, wind, and movement of contaminated tools. The spores infect healthy plants primarily through wounds, natural cracks, or pruning cuts.

Development conditions and impact: The pathogen thrives in warm, humid climates, which are common in many blueberry production regions. Its impact is severe, as the cankers disrupt the vascular system, preventing the transport of water and nutrients. This results in dieback, reduced fruit production, and eventually the death of infected canes or the entire plant.

Control and management measures: Effective disease management relies on an integrated approach to maintain plant health and reduce inoculum levels:

• Selection of resistant blueberry cultivars suited for the local environment.
• Strict sanitation protocols, including pruning and removal of infected stems.
• Proper disposal of infected plant material by burning or burying away from fields.
• Disinfecting pruning shears between plants to prevent mechanical transmission.
• Applying registered fungicides as a preventive measure during the active spore discharge period.