ABSTRACT
The first report of a wilt disease of Medicago sativa L. (lucerne, alfalfa) caused by Verticillium albo-atrum was from Sweden in 1918 (Hedlund, 1923), but during the period 1938–1950 the disease was reported in a number of European countries, including Germany (Richter and Klinkowski, 1938), Holland (Hansen and Weber, 1948), and France (Krietlow, 1962). In the United Kingdom, where there had been a large postwar increase in lucerne cultivation, 12,800 hectares in 1942 to 44,000 hectares in 1954, the first recorded outbreak was in 1952 (Noble et al., 1953). Following this first occurrence the disease spread rapidly, resulting in a decline in the area under cultivation to 15,000 hectares by 1970. Subsequently the disease was recorded in Canada in 1964 (Aube and Sackston, 1964) and in Washington State (Graham et al., 1977), and today the disease is of major significance in North America.
