Wheat powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is one of the most significant diseases affecting production in wheat-growing regions of China. Fluxapyroxad and mefentrifluconazole exhibit broad-spectrum activity against a wide range of plant pathogens, including Bgt. This study presents a comprehensive investigation of the efficacy of fluxapyroxad and mefentrifluconazole in controlling wheat powdery mildew in three Chinese provinces. Sensitivity baselines for Bgt isolates against fluxapyroxad (0.9111 μg/ml) and mefentrifluconazole (1.3224 μg/ml) were established. Bgt isolates collected from 2022 to 2024 demonstrated sensitivity or low resistance to fluxapyroxad and sensitivity, low resistance, or moderate resistance to mefentrifluconazole. The results revealed positive cross-resistance between mefentrifluconazole and tebuconazole but not between fluxapyroxad or mefentrifluconazole and other fungicides. For fluxapyroxad, three site mutations were identified within the SDHD subunit, but they did not result in amino acid changes. For mefentrifluconazole, overexpression of QCYP51A and QCYP51B genes was identified as a significant factor contributing to low-level resistance in Bgt. Both fluxapyroxad and mefentrifluconazole, individually and in combination, exhibited high control efficacy (>89%) against wheat powdery mildew. This research provides valuable insights into the current status of Bgt resistance to these fungicides and offers guidance for their judicious application in the field.
Bi et al. (2026) studied this question.