Strasseria oxycocci

Strasseria oxycocci is a specialized fungal pathogen categorized within the order Sphaeropsidales. It is well-documented in agricultural science as the primary cause of shoot blight in cranberries (Vaccinium macrocarpon). This pathogen acts as a necrotrophic parasite, invading the host tissues and eventually causing localized cell death within the stems and shoots.

The primary symptom of the disease caused by this fungus is the formation of distinct lesions on cranberry vines. As the infection progresses, these lesions turn dark and expand, eventually girdling the shoot. This process cuts off the transport of nutrients and water, leading to the rapid wilting and necrosis of the apical portion of the plant, which negatively impacts fruit set and yield.

The biology of Strasseria oxycocci revolves around the production of pycnidia, which are asexual fruiting bodies that emerge from the epidermis of the infected stems. These pycnidia release masses of conidia, which serve as primary and secondary inoculum. The pathogen thrives under cool, moist conditions, typically overwintering in debris or infected plant tissue left on the field surface.

Environmental conditions play a decisive role in the spread of the disease. High relative humidity and prolonged periods of leaf wetness—often caused by dense canopy structures or improper irrigation management—significantly accelerate spore germination and colonization. Wounds caused by insect pests or frost damage further increase susceptibility, making the crop more vulnerable to infection.

Integrated management practices for controlling this pathogen are essential for sustainable cranberry production:

• Strict field sanitation by removing and destroying symptomatic plant materials.
• Promoting good canopy airflow to reduce moisture accumulation on the vines.
• Strategic application of copper-based or systemic fungicides during high-risk periods.
• Monitoring pest populations to minimize mechanical wounds that facilitate entry.
• Implementation of proper water management to prevent prolonged standing water in low-lying areas.