Madagascar cassava mosaic

Pathogen and disease type. The disease is caused by Begomovirus manihotismadagascarense, a virus belonging to the genus Begomovirus within the Geminiviridae family. It is a viral pathogen that systematically infects the host plant, interfering with essential physiological processes and causing significant morphological changes.

Host crops. The virus specifically targets cassava (Manihot esculenta). As a major staple crop in Madagascar, the impact of this virus on cassava plantations poses a serious threat to agricultural productivity and local food security in the affected regions.

Symptoms and signs. Affected plants exhibit characteristic mosaic patterns on the foliage, including chlorotic spots and green patches. Severe cases involve leaf distortion, curling, and a drastic reduction in leaf size, which leads to stunted plant growth and a significant decrease in the formation of tuberous roots.

Development and severity. The virus is primarily transmitted by the whitefly Bemisia tabaci. The spread of the disease is favored by warm tropical temperatures and high humidity, which support rapid vector population growth. The economic impact is substantial, as infected plants yield significantly fewer and smaller tubers, often rendering them unsuitable for consumption or processing.

Control and prevention. Management strategies focus on planting resistant cassava cultivars and utilizing virus-free propagation material. Essential preventive measures include rogueing of infected plants, controlling whitefly populations through insecticide applications or physical barriers, and maintaining field hygiene to reduce potential reservoir sources of the virus.