Potato mop-top virus

Potato mop-top virus (PMTV) is a serious viral pathogen classified in the genus Pomovirus, family Virgaviridae. It primarily affects potato crops, leading to significant yield losses and internal tuber quality degradation, which makes the produce unmarketable in commercial settings.

The virus is exclusively transmitted by the soil-borne obligate parasite Spongospora subterranea, which also causes powdery scab. The virus survives within the resting spores (sporosori) of this vector, allowing it to persist in the soil for over a decade, making traditional crop rotation challenging for long-term eradication.

Symptoms in the foliage often appear as stunted growth with shortened internodes, giving the plant a mop-like appearance. However, the most economically damaging symptoms are found in the tubers, appearing as concentric rings on the skin or brown necrotic arcs and flecks in the tuber flesh, commonly referred to as "spraing" or "rusting".

The spread of PMTV is highly dependent on environmental conditions that favor the vector. Cool, moist soil conditions during the early stages of tuber development are critical for the transmission of the virus from the soil to the newly forming daughter tubers. Contaminated farm equipment and infected seed tubers are the primary pathways for long-distance dissemination.

• Sourcing certified virus-free seed tubers for all plantings.
• Cultivating potato varieties with known resistance to PMTV and powdery scab.
• Implementing long crop rotations to reduce the resting spore count in the soil.
• Optimizing soil drainage and pH levels to suppress the vector's activity.
• Rigorous sanitation of all agricultural machinery to prevent field-to-field movement.