Disease Note

Fusarium avenaceum as One of the Causal Agents of Seedling Blight of Canola in Alberta. A. I. Calman, Department of Plant Science, University of Alberta, Edmonton, Canada T6G 2P5. J. P. Tewari, and M. Mugala, Department of Plant Science, University of Alberta, Edmonton, Canada T6G 2P5. Plant Dis. 70:694. Accepted for publication 17 March 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-694f.

Seedling blight causes poor establishment of canola (Brassica campestris L. and B. napus L.) in many fields in Alberta, Canada. Rhizoctonia solani Kühn is already known to be one of the causal agents (1,2). During 1984, 2,649 blighted canola seedlings were collected from 73 commercial fields throughout Alberta. Of 2,299 fungal cultures isolated, 142 belonged to Fusarium avenaceum (Corda ex Fr.) Sacc. Pathogenicity testing (3.6 × 10⁶ propagules per kilogram of steamed soil) on B. campestris ‘Candle’ seedlings with two isolates satisfied Koch’s postulates. In addition to reduced seedling emergence, symptoms included constrictions, tapering, and brown lesions on the hypocotyls. This appears to be the first report in Canada on isolation and pathogenicity of F. avenaceum from canola seedlings affected with seedling blight.