Tropical phytophthora

Pathogen and disease type. Phytophthora tropicalis is an oomycete pathogen belonging to the pseudo-fungi group. It is recognized as a highly destructive agent causing systemic infections, root rots, and necrotic lesions. The pathogen is known for its high virulence and the ability to cause rapid decline in host plants under favorable environmental conditions.

Affected crops. This pathogen has a wide host range. It causes significant economic damage to cacao plantations, various orchid species, eucalyptus, and a variety of ornamental and horticultural crops. Its broad host range facilitates its survival in diverse environments, from tropical plantations to commercial greenhouses.

Symptoms and signs. The disease is characterized by dark, water-soaked lesions on leaves, stems, and fruits. Root rot is a common manifestation, leading to systemic wilting of the plant as the vascular system becomes compromised. In high humidity, the affected tissues may display white, sporangial growth on the surface of the lesions.

Development and spread conditions. Phytophthora tropicalis thrives in high-temperature and high-humidity environments. Zoospores are water-dispersed, spreading easily through irrigation, rainfall, or contaminated tools. Poor air circulation and overcrowding create ideal conditions for the rapid transmission of the disease within the crop canopy.

Damage and control measures. The economic impact includes mortality in seedlings and significant losses in fruit production. Effective control involves the use of pathogen-free planting stock, strict sanitation practices, soil drainage improvements, and the strategic application of fungicides such as copper compounds or metalaxyl to mitigate outbreaks.

• Sterilization of agricultural tools and containers.
• Prompt removal and destruction of infected plant debris.
• Management of soil moisture and greenhouse ventilation.
• Implementation of crop rotation where applicable.