Pathogenicity of<i>Fusarium</i>spp. from Diseased Sugar Beets and Variation Among Sugar Beet Isolates of<i>F. oxysporum</i>

Abstract

Sugar beets (Beta vulgaris) with symptoms of Fusarium yellows were collected from fields in California, Colorado, Montana, Oregon, Texas, Wyoming, and Manitoba, Canada, during 1982-1988. Forty-eight isolates of seven species of Fusarium and two nonsporulating, unidentifiable «Roseum» types were obtained from root tissue on a medium selective for Fusarium spp. Three isolates of F. oxysporum (the reported causal agent of Fusarium yellows) from California, one each from Colorado and Texas, and two each from Montana, Oregon, and Canada, a Colorado isolate of F. acuminatum, two isolates of F. avenaceum from Texas, and one «Roseum» type from Colorado all caused foliar yellowing, wilt, root necrosis, and in some cases eventual death of sugar beet seedlings in greenhouse tests (.)