Sweet potato feathery mottle virus

Pathogen and type of disease
The feathery mottle disease of sweet potato is caused by Potyvirus batataplumei, a member of the genus Potyvirus. It is a systemic viral disease that affects the plant's vascular system, leading to physiological stress and metabolic disruption. The virus is characterized by thread-like (flexuous) particles and is highly persistent in infected tissues.

Host range
The primary host for this pathogen is the sweet potato (Ipomoea batatas). Because the virus is systemic, it readily colonizes vegetative parts, making propagation via slips or tubers a significant pathway for the virus to persist and move into new planting seasons. It remains a major concern in regions where sweet potato cultivation is intensive.

Symptoms and signs of infection
The characteristic symptoms include feathery, chlorotic patterns or vein clearing on the leaves. Infected plants may exhibit stunted growth, reduced leaf size, and occasional leaf distortion. While some varieties may show mild symptoms, others can experience severe yield losses if environmental conditions favor rapid viral replication.

Conditions for development and spread
The virus is primarily transmitted by aphids in a non-persistent manner, meaning they pick up the virus from an infected plant and transmit it to a healthy one during feeding. Environmental factors that promote aphid activity and high insect populations contribute significantly to the disease incidence. Additionally, the movement of infected plant material between fields or regions is a primary cause of long-distance dissemination.

Economic impact and management
The impact of this virus includes reduced tuber quality, size, and overall crop yield. Effective management requires an integrated approach to crop health:

• Sourcing clean, virus-indexed propagation material.
• Implementing rigorous vector control programs using systemic insecticides.
• Removing and destroying symptomatic plants as soon as they are spotted in the field.
• Maintaining field hygiene and controlling weeds that might serve as alternative virus reservoirs.