Abstract:

The purpose of this study was to investigate the combined virulence of prothioconazole and fluazole hydroxylamine against fusarium head blight caused by Fusarium graminearum. In this study, the mycelial growth rate method was used to determine the indoor biological activity of prothioconazole and fluazole acylhydroxylamine against Fusarium graminearum, and to determine the optimal ratio of prothioconazole and fluazole acylhydroxylamine for the control of fusarium head blight. The results showed that the EC₅₀ levels of prothioconazole and fluazole acylhydroxylamine against fusarium head blight were 22.44 and 0.33 mg·L^-1. Among the three different ratios of prothioconazole and fluazole hydroxylamine, the EC₅₀ was the smallest at 2∶3, which was 0.19 mg·L^-1. The EC₅₀ value was the highest at 1∶1 ratio, which was 0.47 mg·L^-1. The results showed that the co-toxicity coefficients of prothioconazole and fluazole hydroxylamine were 137.54, 285.91 and 175.36, respectively, with the weight ratios of 1∶1, 2∶3 and 1∶2, respectively. All things considered, the best blending effect of prothioconazole and fluazole hydroxylamine at 2∶3 was the best. The control efficacy of 300, 400 and 500 mL·hm^-2 of 50% prothioconazole fluazole hydroxylamine suspension on fusarium head blight was 91.76%, 97.03% and 99.77%, respectively, after 25 days. 50% prothioconazole fluazole hydroxylamine suspension can prevent and control fusarium head blight, which is used in the early stage of fusarium head blight, applied twice, and the interval between the two applications is about 10-15 days.

Key words: prothioconazole, fluazole hydroxylamine, fusarium head blight, co-toxicity, field efficacy