Verticillium Wilt of Alfalfa

Abstract

Verticillium wilt is a serious disease of alfalfa with the potential to reduce yields as soon as the second harvest year and to limit productive stand life to 3 years or less. Verticillium wilt (VW) , a fungus-incited disease, was discovered in Sweden in 1918 and was responsible for major crop losses in the cooler alfalfa-growing regions of Europe during the 1950s. The disease was detected in 1962 in Quebec and British Columbia, but didn't become established in North America until the mid 1970s. Following its detection in Washington State in 1976, the disease became widely distributed throughout the Pacific Northwest where it caused substantial losses. This is also the production region for much of New York's alfalfa seed. Infested seedlots have played a major role in the spread of VW into most of the northern tier of states and the provinces of Canada where the disease is now found.