Dioscorea yellow mosaic virus

The causative agent of the disease is Macluravirus dioscoreaflavitessellati, a plant virus within the Macluravirus genus of the Potyviridae family. As an obligate parasite, it disrupts normal plant physiology, causing systemic infection that poses a significant threat to global yam production.

The primary host for this virus is the yam (Dioscorea spp.). Because yams are propagated vegetatively using tubers, the virus can easily become systemic within a crop cycle, spreading effectively if infected tubers are used as seed material for the next planting season.

Symptomatology typically includes yellow mosaic patterns on the foliage, where leaves exhibit mottled yellow and green discoloration. Advanced stages of infection often feature leaf distortion, stunting of the vines, and reduced tuber quality and size. These symptoms are most visible during periods of rapid leaf development.

Disease spread is facilitated by insect vectors, primarily aphids, which transmit the virus while feeding on plant sap. Environmental conditions that support large aphid populations, such as warm and humid climates, significantly increase the rate of viral transmission throughout the plantation.

Effective management requires a combination of strategies to minimize the viral load in the field. Essential measures include:

• Sourcing high-quality, virus-indexed seed tubers for planting.
• Prompt roguing and destruction of symptomatic plants to reduce inoculum.
• Implementing vector control programs to manage aphid populations.
• Sanitizing pruning and farming equipment to prevent mechanical transmission.
• Maintaining strict isolation of fields from known infected areas.