Calonectria henricotiae

Calonectria henricotiae is a pathogenic fungus that poses a significant threat to various ornamental plants. It belongs to the Calonectria species complex, which is widely recognized in plant pathology for causing devastating necrotic diseases, particularly in nursery production and greenhouse environments where environmental conditions are optimized for both plant growth and fungal development.

The primary hosts for this pathogen include Buxus species and other woody ornamentals. The disease primarily targets the root system and the stem base, leading to systemic physiological collapse. Once the pathogen colonizes the vascular tissues, the plant's ability to uptake water and nutrients is severely compromised, resulting in rapid decline and mortality.

Symptoms often appear as chlorosis followed by wilting and necrosis of foliage. A critical diagnostic feature, especially under high humidity, is the emergence of white to yellowish conidial masses on the surface of infected stems and roots. The presence of these structures confirms the active sporulation phase of the fungus and indicates a high risk of spread to neighboring plants.

The development and spread of Calonectria henricotiae are heavily influenced by environmental moisture. High soil moisture content and elevated temperatures create an ideal environment for the fungus to produce spores. The pathogen can survive for extended periods in the soil, making it a persistent threat in nurseries where substrate hygiene is not strictly maintained.

• Implement rigorous quarantine for new plant arrivals.
• Ensure excellent drainage in pots and planting beds.
• Sanitize tools and surfaces using appropriate disinfectants.
• Avoid overhead irrigation that splashes soil onto stems.
• Apply systemic fungicides as a preventative measure during high-risk periods.

Integrated disease management is essential for controlling this pathogen. Growers must combine cultural practices, such as removing infected debris and improving aeration, with the judicious use of fungicides. Because this pathogen is soil-borne, early detection and containment are the most effective strategies to prevent large-scale losses in ornamental cultivation.