Botryosphaeria stem blight

Botryosphaeria stem blight, caused by the fungus Botryosphaeria vaccinii, is a significant disease affecting commercial production of blueberries and cranberries. It belongs to the Ascomycota phylum and acts as a parasitic pathogen, targeting the woody tissues of the host plants to derive nutrition, leading to severe decline.

The primary symptom of infection is the sudden wilting of individual branches or entire canes during the growing season. Lesions often form at the base of the stems or near pruning wounds. As the fungus colonizes the vascular tissue, it disrupts water and nutrient transport, which eventually kills the affected plant parts.

The disease cycle is characterized by the production of pycnidia within the infected bark. During warm and rainy weather, spores are released and dispersed by splashing water, wind, and movement of equipment. The pathogen can survive in dead wood for several years, making it an persistent threat in managed plantations.

Development and spread of Botryosphaeria vaccinii are highly dependent on climatic conditions and host vulnerability. High humidity and prolonged leaf wetness facilitate spore germination and entry into the plant. Plants stressed by environmental factors, such as winter injury or drought, show significantly higher susceptibility to the disease.

Integrated management is essential for controlling this pathogen effectively. Growers should prioritize the pruning of infected wood, ensuring that cuts are made well below the necrotic area. Furthermore, maintaining plant vigor through proper irrigation and nutrition, as well as applying preventative fungicides, is crucial for minimizing crop losses in fields.