Dioscorea mosaic virus

Causal agent and disease type. Sadwavirus dioscoreae is the causative agent of this viral disease. It is a member of the genus Sadwavirus and the Secoviridae family. The disease is systemic, causing severe metabolic disturbances within the host plant, ultimately affecting its vigor and productive potential.

Host range. The virus primarily affects species of yam (Dioscorea spp.). It represents a significant constraint to yam production globally, particularly in tropical regions where yam is a staple food crop and an essential component of local agricultural systems.

Symptoms and signs. Infected plants typically display distinct mosaic patterns on leaves, characterized by alternating light and dark green areas. Symptoms often include leaf distortion, mosaic mottling, and general stunting, leading to a noticeable reduction in tuber weight and overall crop yield.

Development and transmission. The virus spreads predominantly through the use of infected tubers as planting material. Additionally, mechanical transmission occurs via contaminated farm tools during agricultural practices, and certain insect vectors may contribute to the spread of the virus within and between fields.

Economic impact and management. Damage caused by this virus results in considerable economic losses due to diminished tuber quality and yield. Control measures focus on:

• Sourcing certified virus-free planting material.
• Implementing rigorous sanitation protocols for field tools.
• Rogueing infected plants to limit further spread.
• Managing insect vector populations in the yam field.