Inhibitory activity of triticonazole and its mixture against Fusarium graminearum in Henan Province and its control efficacy on Fusarium head blight of wheat

Fusarium head blight (FHB), caused by Fusarium graminearum, is one of the important diseases in wheat production. In order to clarify the activity of triazole fungicide triticonazole against F. graminearum, the toxicity of triticonazole against F. graminearum at different developmental stages was determined in the lab. It was found that the sensitivity from low to high is: conidia germination < germ tube elongation < mycelial growth, and the EC₅₀ values were 18.16, 1.332, and 0.4613 μg/mL, respectively. The sensitivity of 101 strains of F. graminearum collected from 9 cities in Henan Province to triticonazole was determined by the mycelial growth rate method. The results showed that the EC₅₀ values ranged from 0.0586 to 0.9183 μg/mL, with an average of (0.3866 ± 0.1969) μg/mL. The sensitivity frequency distribution showed a continuous single-peak curve. The average EC₅₀ value could be used as the sensitivity baseline of F. graminearum to triticonazole in Henan Province. The combined toxicity assessment of triticonazole with five other fungicides including pydiflumetofen, carbendazim, fludioxonil, phenamacril, and prochloraz against F. graminearum revealed synergy ratio (SR) ranged from 0.53 to 3.76. Different combinations and proportions of the compound showed additive or synergistic effects. Among them, the synergistic effect was the most obvious (SR = 3.76) when prochloraz and triticonazole were compounded at a mass ratio of 1∶3. The indoor in vitro control effect determination showed that at a dose of 400 μg/mL of active ingredient, the compound prepared with a mass ratio of 1∶3 of prochloraz and triticonazole had the highest therapeutic efficacy of 82.63%. The research results help guide the scientific and rational use of triticonazole and provide a theoretical basis and data support for the comprehensive prevention and control of wheat FHB.