Sweet potato feathery mottle virus

Sweet potato feathery mottle virus (SPFMV) is the most prevalent and economically damaging virus affecting sweet potato crops worldwide. Belonging to the genus Potyvirus, it exists as flexuous filamentous particles containing single-stranded RNA. This virus is notorious for its ability to cause severe disease complexes when infecting plants in combination with other viral pathogens, significantly impacting agricultural yield.

The primary host for this virus is the sweet potato (Ipomoea batatas). The virus infects all plant tissues and is often systemic, meaning it spreads throughout the entire plant including roots, vines, and leaves. Because many sweet potato varieties show mild symptoms or are asymptomatic carriers, the virus often remains undetected in agricultural systems until substantial damage has already occurred.

Symptoms of SPFMV infection are diverse and depend heavily on the specific viral strain and the host cultivar. The most characteristic symptom is the feathery chlorotic pattern along the leaf veins, accompanied by general mottling or mosaic patterns on the foliage. In severe cases, particularly when interacting with other viruses, the infection leads to internal cork disease in roots, causing necrosis and cracking that renders the produce unmarketable.

Transmission of the virus occurs primarily through aphids (Aphididae) in a non-persistent manner. This means that insects can acquire and transmit the virus within seconds of feeding on an infected plant. Additionally, the virus is widely distributed through vegetative propagation, as infected cuttings provide a continuous reservoir for the pathogen to spread to new fields and seasons.

• Utilizing virus-indexed, certified disease-free planting material.
• Implementing strict insect vector control programs during the growing season.
• Maintaining spatial isolation between new fields and older, potentially infected crops.
• Systematic roguing of plants showing viral symptoms to limit spread.
• Controlling alternative weed hosts that may harbor the virus.

The economic impact of SPFMV is significant, particularly in developing regions where sweet potatoes are a staple crop. Beyond direct yield losses, the virus compromises the nutritional and sensory quality of the roots. Effective management requires an integrated approach that combines careful selection of planting stock with ongoing monitoring for both the virus itself and its insect vectors to maintain profitable production levels.