Temporal Changes in Sensitivity of Fusarium asiaticum Field Populations to Different Fungicidal Modes of Action

Fusarium head blight (FHB), one of the most economically important diseases on wheat, is primarily managed through the application of chemical fungicides during the heading and flowering stages. To assess the long-term impact of different fungicidal mechanisms on the sensitivity of FHB pathogens, this study evaluated temporal changes in the sensitivity of Fusarium asiaticum to phenamacril (a novel cyanoacrylate fungicide) and tebuconazole (a sterol demethylation inhibitor fungicide). Sensitivity was determined by measuring mycelial growth inhibition in F. asiaticum field populations collected in 2008 (100 strains), 2021 (50 strains), and 2023 (50 strains) from Jiangsu and Anhui provinces of China, where FHB pressure and fungicide usage are high. A significant decline in F. asiaticum sensitivity to phenamacril over 15 years was observed, with EC₅₀ values nearly doubling between 2008 and 2023. In contrast, no notable change in sensitivity to tebuconazole was observed over the same period, indicating its stable inhibitory effect on F. asiaticum. These findings highlight the challenge of F. asiaticum adaptation to phenamacril, posing a significant concern for the long-term management of FHB in wheat cultivation.