African cassava mosaic

African cassava mosaic disease is caused by the Begomovirus manihotisafricaense, a serious viral pathogen that significantly impacts the cultivation of cassava (Manihot esculenta). This disease is widespread across sub-Saharan Africa, representing one of the most significant biological constraints to cassava production globally.

The transmission of the virus occurs primarily through the whitefly (Bemisia tabaci). When these insects feed on infected phloem, they acquire the virus and transmit it to healthy plants. Another major pathway of disease dissemination is the use of infected vegetative cuttings for planting, which facilitates the spread of the virus across large geographic regions and between different farming communities.

Diagnostic symptoms include a characteristic chlorotic mosaic pattern on the leaves, where yellow and green patches are interspersed. Affected plants often exhibit leaf distortion, puckering, and severe dwarfing. The stunted canopy growth directly leads to reduced photosynthesis, which ultimately results in fewer and smaller starchy storage roots.

The economic impact of this disease is profound, often leading to total crop failure in highly susceptible varieties. Because cassava is a primary calorie source for millions, the reduction in tuber quality and quantity caused by the virus has severe implications for food security, causing significant losses in farm household income.

Management and prevention programs are centered on the deployment of resistant cassava varieties, which is the most sustainable solution. Furthermore, farmers are encouraged to implement strict phytosanitary practices, such as roguing (removing) infected plants to prevent inoculum buildup. Controlling whitefly populations and ensuring the use of virus-free stem cuttings remain critical components of disease mitigation.