Risk factors

The disease is favoured by cold and humid climates and in damp, heavy or peaty soils as high soil water content is required for the release of zoospores of Spongospora subterranea and the infection of potato roots.

PMTV is spread from field to field in resting spores of S. subterranea carrying the virus and present on potato tubers or in contaminated soil. 

Movement of infected tubers or plants, soil, machinery or manure therefore increases the risk of spreading the disease.