Response of soybean cultivars to root rot caused by Fusarium species

Fusarium root rot complex is a major soybean disease in Canada and the United States. Since 2006, four Fusarium species, F. oxysporum Schlechtendahl emend. Snyder & Hansen, F. graminearum Schwabe, F. avenaceum (Corda: Fr.) Sacc., and F. tricinctum (Corda) Sacc., have frequently been isolated from soybean roots in eastern Ontario, Canada. The objective of the current study was to screen 57 soybean cultivars that are commercially available in Canada for resistance to these four Fusarium root rot pathogens under greenhouse conditions. Based on root rot severity and reductions in seedling emergence, plant height and root dry weight, F. avenaceum was the most pathogenicspec ies, followed by F. graminearum. The pathogenicity of F. oxysporum on soybean cultivars was not significantly different from that of F. tricinctum, but was significantly lower than that of F. graminearum. In replicated experiments, six, nine, eleven and seven cultivars were consistently rated as the most resistant to F. avenaceum, F. graminearum, F. oxysporum and F. tricinctum, respectively. Cultivar Maple Amber was resistant to all four Fusarium species based on root rot severity, while cultivar Altona was resistant to F. avenaceum, F. oxysporum and F. tricinctum. Four cultivars, 9004, AC Harmony, Lanark and Maple Arrow, each showed resistance to two different Fusarium species.