Distribution of Potato Mop‐top Virus in Scotland in Relation to Soil and Climate

Abstract
SUMMARY: Although more than half the potato stocks examined seemed free of potato mop‐top virus (PMTV), infection was found in 66 cultivars. In the field, up to 48 per cent of plants in a stock were affected, and in the store up to 38 per cent of tubers. PMTV‐infested fields occurred in 13 Scottish counties on several types of both freely drained and imperfectly drained soil. The occurrence of the virus seems unrelated to accumulated temperature but is strongly related to annual rainfall. Little PMTV occurred where the rainfall was less than 30 in. (760 mm) but its prevalence increased with increase of rainfall from 30 to 45 in. (760 to 1,140 mm) and above 45 in. the probability of infection was great.