APHID MOVEMENT AND VIRUS SPREAD IN SEED POTATO AREAS OF ENGLAND AND WALES.

This article focuses on the investigations that were done in the 1950s to measure and compare virus spread in the seed potato growing areas of England and Wales. The pattern of aphid infestation differed in three years. In 1955, M. persicae was first detected in the crops in late June in Cotswolds, Devon, North Wales and the East Riding of Yorkshire. Exceptionally early immigration occurred in 1957, when large numbers of M. persicae and other species were flying in the early part of May, often before any potato plants had emerged. Calculation of the angle of colonization proved to be a much more sensitive method of detecting the presence and activity of aphids in seed areas than was trapping, at some sites, quite high angles of colonization were obtained although no alate M. persicae was trapped.