VERTICILLIUM WILT OF FORAGE LEGUMES IN CANADA

Abstract

Verticillium albo-atrum R. and B. was isolated from diseased alfalfa and ladino clover at Normandin, Que., and V. dahliae Kleb. from red clover at Ottawa, Ont., in 1962. Isolates of V. albo-atrum were more pathogenic than V. dahliae to alfalfa and birdsfoot trefoil, and V. dahliae was more pathogenic to red clover. Comparative inoculation tests in the greenhouse showed that the Canadian isolates were as virulent on forage legumes as were legume isolates obtained from Britain. All isolates tested were strongly pathogenic to lupine and sainfoin. Birdsfoot trefoil, lupine, and ladino clover, not previously reported as hosts of Verticillium, proved susceptible in greenhouse tests.This is one of the first reports of virulent Verticillium on forage legumes in North America. Since diseased plants were found only at two experimental stations, the pathogen may have been introduced on seed imported from Europe. No Verticillium wilt was found at the same locations in 1963.