Fusarium head blight (FHB) is one of the most serious diseases affecting cereal crops across Canada. Fungicide application is an important strategy to mitigate the disease; however, determining the correct timing of a fungicide application is difficult. The aim of this study was to determine the impact of fungicide (metconzole) applications at BBCH 59, 61, 65, 69 and a dual application (61 and 69) to mitigate FHB (FHB index and FDK content), yield and quality of winter, bread and durum wheat, and barley. Under the environmental conditions of this study, which did not favor FHB development, FHB severity was low (as measured by FHB index and FDK content) and fungicide application rarely improved yield or quality of either wheat or barley. There was little evidence of positive physiological effects of the fungicide treatments.  Fungicide application at BBCH 59 (end of heading, just prior to anthesis) was not usually the most effective application timing for FHB mitigation, and on some occasions was no better than no fungicide application, as measured by FHB index (severity in the field) and FDK content.  Application at BBCH 69 (late anthesis) was usually equally effective as fungicide applications at BBCH 61 and 65 to mitigate FHB index and FDK content.  Although the fungicides applied at heading and anthesis to cereal crops in this study provided little benefit for FHB mitigation, analysis of FHB index and FDK content indicated that optimum fungicide application timing was between BBCH 61 and 69.  The dual application was effective to reduce FHB index and FDK content, however, it did not appear to be superior to a single application.

The analyses of 3ADON and 15ADON chemotypes revealed significant interactions among temperatures, incubation periods, and experiments. Results were highly variable between experiments for both chemotypes, although both appeared to follow somewhat similar trends in DON accumulation: warmer temperatures (24 and 30^oC) and longer incubation periods (21 to 28 days) resulted in increased DON concentrations. For the 3ADON chemotype incubation periods at favorable temperatures had less impact on production that these factors did for the 15ADON chemotype, which consistently yielded higher DON levels with longer incubation periods, regardless of temperature. Despite differenced due to temperature and incubation period, it was clear that the 3ADON chemotype generated much higher amounts of DON compared to the 15ADON chemotype, suggesting that 3ADON is the more aggressive chemotype.