Abstract
Potato mop-top virus (PMTV) is a soil-borne virus that constrains potato production in temperate regions worldwide and has recently been detected in Australia, including north-west Tasmania. Infection occurs via roots and spreads systemically, but virus distribution within plants is uneven and symptoms are often absent. Tuber spraing, characterized by internal necrotic arcs and rings, is the most economically important symptom, while latent post-harvest necrosis complicates detection and risk assessment. PMTV is transmitted by Spongospora subterranea , whose motile zoospores mediate infection and resting spores enable long-term soil persistence. Environmental conditions strongly influence transmission and symptom expression, yet virus–vector–host interactions remain poorly understood. To date, no potato cultivar has been identified that exhibits strong infection resistance, and symptomless cultivars can act as virus carriers. Economic impacts primarily reflect tuber quality defects. Improved understanding of transmission, symptom development, and cultivar responses is needed to support predictive risk assessment and integrated management.