Tomato stem rot

Tomato stem rot is a destructive fungal disease caused by the pathogen Boeremia lycopersici. This pathogen is a significant threat to tomato crops worldwide, particularly in greenhouse cultivation where high humidity and temperature control can inadvertently create optimal conditions for fungal development.

The disease affects all stages of plant growth. The fungus primarily invades the stem, causing necrotic lesions that can girdle the main stalk near the soil line. This restriction of water and nutrient transport leads to rapid wilting, chlorosis, and ultimately the death of the infected plant, causing substantial economic losses.

Diagnostic signs include dark, sunken lesions on stems that develop brown, dry spots. On leaves, the symptoms appear as small, dark brown circular lesions. The most distinct feature is the appearance of small, black, pin-head-sized fruiting bodies called pycnidia, which emerge within the necrotic tissue and act as the primary inoculum for the next infection cycle.

Environmental factors are crucial for the spread of Boeremia lycopersici. High humidity (above 80%), cool to moderate temperatures, and poor air circulation in tunnels promote sporulation. The spores are easily dispersed by splashing water, wind, and contaminated tools, making hygiene a critical component of disease management in agricultural operations.

• Implement strict crop rotation schedules.
• Use certified, disease-free seed stock.
• Maintain optimal greenhouse climate control and ventilation.
• Apply preventive fungicide treatments during periods of high humidity.
• Remove and destroy all infected plant debris immediately after harvest.

Integrated pest management (IPM) is essential for controlling this disease. By combining cultural practices, such as sanitizing equipment and controlling irrigation methods, with targeted chemical interventions, growers can significantly reduce the incidence of stem rot and ensure crop health throughout the growing season.