Pathogenicity of Fusarium graminearum and F. poae Causing Fusarium Head Blight on Barley Under Controlled Conditions

Fusarium head blight (FHB) is one of the most damaging diseases of barley. FHB is caused by a species complex of Fusaria, of which Fusarium graminearum is the species of greatest concern for barley in Canada. Field surveys showed that two or more Fusarium species often co-exist within the same field or grain sample and F. poae has been reported as another dominant species in barley in eastern Canada. The aim of this study was to determine the pathogenicity of F. graminearum, F. poae and a co-inoculation of both species causing FHB in barley under controlled conditions. Spray inoculation was performed on two susceptible barley genotypes at 10 to 14 days after heading. FHB severities were rated on a scale of 0-9 at 4, 7, 14, 21, and 28 days after inoculation. There was a significant difference in FHB severity between F. graminearum and F. poae, with F. graminearum being more pathogenic species. F. poae was less pathogenic and not statistically different from the control treatment (inoculated with deionized water only). When heads were co-inoculated with the mixture of both Fusarium species, the resulting FHB severity was significantly lower than that caused by F. graminearum alone, indicating that the presence of F. poae may reduce the pathogenicity of F. graminearum in causing FHB.