African cassava mosaic

African cassava mosaic is a devastating viral disease caused by the Begomovirus manihotismalawiense, a pathogen belonging to the Geminiviridae family. This virus is characterized by a circular single-stranded DNA genome and is a major threat to food security in tropical regions where cassava serves as a staple food source.

The disease primarily targets cassava (Manihot esculenta). Once infected, the virus spreads systemically throughout the plant, disrupting physiological processes, hindering nutrient translocation, and drastically reducing the development of the starchy storage roots that are crucial for yield.

Symptoms are easily identifiable in the field and include:

• Characteristic mosaic patterns with chlorotic and green patches on leaves
• Severe leaf distortion and curling
• Reduction in leaf size (stunting)
• General plant dwarfing and reduced canopy cover

The transmission of the virus is predominantly mediated by the whitefly (Bemisia tabaci), which acts as a vector. Environmental conditions, particularly warm temperatures and high humidity, favor the rapid multiplication of whiteflies, thereby accelerating the spread of the virus within and between plantations.

Management and prevention strategies focus on breaking the disease cycle. Key interventions include: the cultivation of resistant or tolerant cassava varieties, the use of virus-free planting material derived from tissue culture, rigorous roguing of infected plants, and the integrated pest management of whitefly populations to minimize transmission risks.