Cassava

Cassava (Manihot esculenta) is subject to various phytopathogens that significantly impact agricultural production. These pathogens encompass a diverse group of organisms, including viruses, bacteria, and fungi, which specifically target the foliage, stems, and the starch-rich tuberous roots of the plant.

Key diseases affecting the crop include the Cassava Mosaic Disease (CMD), caused by geminiviruses, and Cassava Bacterial Blight (CBB), triggered by the bacterium Xanthomonas axonopodis pv. manihotis. These pathogens can lead to severe stunting, leaf necrosis, and substantial reductions in tuber quality and yield.

The biology and lifecycle of these pathogens are heavily influenced by environmental factors such as high humidity and temperature. Fungal pathogens, like Phytophthora species causing root rot, flourish in poorly drained soils where the pathogen persists in the form of mycelium or spores, ready to infect root tissues when favorable conditions arise.

Disease spread is primarily mediated through infected vegetative cuttings (stem cuttings used for propagation) and insect vectors like the whitefly (Bemisia tabaci). Secondary spread occurs through water runoff and mechanical transmission, often facilitated by farm tools that have not been adequately sanitized between operations.

Effective control requires a multi-faceted strategy focused on prevention and eradication. This includes the deployment of disease-resistant germplasm, rigorous sanitation of the planting environment, and regular monitoring for vector populations. Chemical intervention should be targeted and combined with cultural practices to ensure long-term sustainability.

• Use of certified, virus-free planting material.
• Crop rotation to break the pathogen lifecycle.
• Removal and destruction of symptomatic plants.
• Sanitization of tools to prevent mechanical transmission.