Cylindrocladium stem canker

Cylindrocladium stem canker, caused by the fungus Cylindrocladium theae, is a severe fungal disease affecting a variety of ornamental plants. The pathogen is recognized for its aggressive colonization of vascular tissues, which can lead to significant structural damage and the eventual death of the host plant if not managed promptly.

The fungus primarily targets Azalea species, although it can infect other ornamental shrubs within nurseries. The disease is highly problematic in humid environments where plants are grown in close proximity, allowing the fungus to spread efficiently through water splashes and contaminated soil media.

Symptoms typically begin as small, water-soaked spots on leaves that soon enlarge and turn dark brown. The most diagnostic symptom, however, is the development of sunken stem cankers. These lesions often restrict water and nutrient transport, resulting in wilting, chlorosis, and branch dieback. In high-humidity conditions, white mycelium may appear on the surface of the cankers.

Development and spread are strongly correlated with warm, humid conditions (temperatures between 20°C and 25°C). The fungus thrives in stagnant, water-logged conditions, which facilitate the production and movement of spores. Proper air circulation and effective drainage are critical to minimizing the environmental suitability for the pathogen.

• Maintain low relative humidity within the greenhouse.
• Use certified, disease-free propagation material.
• Sterilize all pots, tools, and surfaces between production cycles.
• Apply preventative fungicides based on local regulatory guidelines.
• Isolate symptomatic plants immediately to prevent secondary spread.

Integrated management is essential, combining rigorous hygiene protocols with a balanced chemical application program. Growers must focus on eliminating sources of inoculum, such as infected debris, and monitoring moisture levels to disrupt the life cycle of the pathogen. Early detection remains the most effective strategy for preserving plant health in nursery operations.