Some epidemiological approaches to the control of aphid-borne virus diseases in seed potato crops in northern Europe.

An account is given of progress during the last 30 years in knowledge of the epidemiology of diseases caused by aphid-borne viruses in seed potato production areas of northern Europe. During this period, Potato leafroll virus (PLRV) and strains of Potato virus Y (PVY(O), PVY(N)) were consistently the most prevalent and harmful. The main factors influencing spread involve the amount of initial virus inoculum in seed crops, agricultural practices in relation to seed potato production, the status of aphids as colonising or transient vectors in the crop, variation in their life cycles and behaviour, effects of environmental factors on aphid population dynamics, and the interaction between aphid phenology and mature plant resistance. Lessons have been drawn from comparisons of the causes of outbreaks of PLRV and PVY, and various comprehensive models have been designed to predict virus spread and optimise control. The accuracy and reliability of virus detection, and chemical control of aphids have been considerably improved, but use of the latter has been severely affected by the development in Myzus persicae of resistance to most types of insecticide. It is suggested that more attention should be given to breeding virus-resistant cultivars that would lead to decreased pesticide use and thus promote more integrated environment-friendly strategies for control.