The effect of <i>Fusarium graminearum</i> 3-ADON and 15-ADON isolates on Fusarium head blight symptoms, Fusarium damaged kernels and mycotoxins production, in inoculated and field grown winter wheat

Fusarium head blight (FHB), caused by Fusarium spp., is a fungal disease affecting cereals and results in millions of dollars in losses in Canada. Deoxynivalenol (DON) is the most concerning Fusarium mycotoxin. A common way to screen wheat cultivars for FHB resistance and DON production is by spray-inoculation with isolates of Fusarium graminearum (Schwabe) in the field. The two main chemotypes of F. graminearum in Canada are 15-acetyldeoxynivalenol (15-ADON) and 3-acetyldeoxynivalenol (3-ADON). The objectives of this study were (1) to evaluate FHB symptoms, Fusarium damaged kernels (FDK) and mycotoxins accumulation in winter wheat ‘Emmit’ and ‘25R40‘, after spray inoculation with 15-ADON and 3-ADON F. graminearum isolates in the field, (2) to investigate relationship among FHB related traits, (3) to evaluate FDK and DON ratio. 3-ADON isolates had significantly higher FHB index (77.9% vs. 71.4%), FDK level (52.4% vs. 45.8%), and DON accumulation (48.4 ppm vs. 38.7 ppm), compared with 15-ADON isolates in just one, out of four environments. Ratio between DON accumulation and FDK level was variable across the environments. Percentage of 3-ADON, of total DON concentration, was higher, after spray-inoculation with 3-ADON F. graminearum isolates, than percent of 15-ADON in total DON amount, after inoculation with15-ADON F. graminearum isolates. Correlation between FHB visual symptoms and FDK/DON level was high in years with higher values, but low or no significant when values were low. A significant difference among the isolates, within each chemotype group existed. A highly pathogenic isolates of 3-ADON and 15-ADON F. graminearum chemotypes are recommended for screening wheat.