2025/09/25 by Meng Cai, Zhenyuan Sun, Chunyan Yin +4 · 1 voice
Agricultural and Biological Sciences · #Fungal Plant Pathogen Control #Nematode management and characterization studies #Plant Disease Resistance and Genetics
paper · doi:10.1094/pdis-06-25-1253-re
openalex publication_date 2025/09/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Fenopyramid is a new succinate dehydrogenase inhibitor (SDHI) that will be soon launched on the market. Sensitivity detection and resistance risk assessment should be performed promptly to track the emergence of fenopyramid resistance and establish resistance management strategies. In this study, the sensitivity of 78 Rhizoctonia solani isolates to fenopyramid was evaluated, along with resistance risk, cross-resistance patterns, fitness costs, and resistance mechanisms in the laboratory. Three low-level resistant mutants and three high-level resistant mutants were obtained by repeated exposures of wild-type sensitive isolates to fenopyramid. The fitness in mycelial growth, mycelial biomass, and pathogenicity of the low-level resistant mutants were less than or similar to that of the parental isolate. There was no fitness cost in the high-level resistant mutants in comparison with that of the parental isolate. Fenopyramid had moderate to strong cross-resistance with commonly used SDHIs (thifluzamide, boscalid, carboxin, and flubeneteram) and non-SDHIs (fluazinam). Overall, the results suggest that the resistance risk of R. solani to fenopyramid is moderate. Mixtures of fenopyramid with four demethylation inhibitors (DMIs) showed synergistic effects. Therefore, it is recommended to mix fenopyramid with DMIs in a proper mass ratio to avoid and delay the development of fenopyramid resistance. No mutations or significant expression changes were detected in the target-site genes SDHA, SDHB, SDHC, and SDHD. Other resistance mechanisms may be responsible and require further investigation.