Thielaviopsis paradoxa

Systematic position and characteristics: Thielaviopsis paradoxa is a serious fungal pathogen belonging to the kingdom Fungi. It is the asexual (anamorphic) stage of the ascomycete fungus Ceratocystis paradoxa. As a facultative parasite, it exhibits significant soil-borne persistence and can survive as a saprophyte on plant debris, making it a persistent challenge in agricultural environments.

Diseases and host plants: The pathogen is responsible for various severe conditions including black rot, basal stem rot, and crown rot. Its host range is extensive, primarily impacting tropical crops such as pineapples, sugarcane, bananas, cocoa, and oil palms. It is particularly notorious for causing substantial losses in pineapple production during post-harvest storage.

Biology and life cycle: The fungus reproduces via two types of spores: endoconidia and thick-walled chlamydospores. Chlamydospores act as dormant structures that withstand extreme conditions in the soil. The disease spreads through infected planting material, contaminated tools, water splash, and wind, quickly colonizing host tissues through physical wounds or natural openings.

Environmental conditions and impact: Development is favored by high humidity (80%+) and warm temperatures between 25°C and 30°C. The pathogen is highly destructive because it can rapidly colonize fruits and stems, leading to severe decay, seedling damping-off, and total loss of commercial value. In post-harvest settings, it can cause epidemic levels of rot if environmental controls are not maintained.

Control and management strategies: Managing Thielaviopsis paradoxa requires integrated pest management (IPM) practices:

• Utilizing disease-free planting material and resistant cultivars.
• Removing and destroying infected crop residues to reduce inoculum levels.
• Disinfecting pruning and harvesting tools with alcohol or chlorine solutions.
• Applying fungicide dips to fruit surfaces immediately after harvest.
• Improving field drainage and managing temperature during storage to suppress fungal growth.