Sensitivity of Fusarium pseudograminearum isolates to fludioxonil in Henan Province, China

Wheat crown rot caused by Fusarium pseudograminearum has become an important soil-borne disease and affects the quality and yield of wheat. In order to detect the sensitivity of F. pseudograminearum to fludioxonil in Henan Province, China, 105 isolates of F. pseudograminearum were collected from six cities in 2019. Sensitivity was determined by the mycelial growth rate method, then the methods of least-significant difference (LSD) and SPSS cluster were used for result analysis. The sensitivity of F. pseudograminearum to carbendazim and tebuconazole was determined and the correlation coefficient which existed between fludioxonil and the two fungicides, carbendazim and tebuconazole was analyzed. The results showed that the minimum inhibitory concentration (MIC) of fludioxonil was 0.2400 μg/mL. The sensitivity frequency distribution was a continuous single peak curve, and the EC₅₀ value ranged from 0.0027 to 0.0470 μg/mL. The average EC₅₀ value of (0.0263 ± 0.0101) μg/mL, could be used as the sensitivity baseline of the pathogen to fludioxonil. The variance analysis results showed that the sensitivity of the different cities to fludioxonil was different, and the EC₅₀ value ranged from 0.0150 to 0.0335 μg/mL. The maximum EC₅₀ value of the isolate from Zhongmu County Zhengzhou City was 16.78 times bigger than the minimum value. Cluster analysis showed that there was no significant correlation between the sensitivity of isolates to fludioxonil and their geographical origin. The mean EC₅₀ values of carbendazimand tebuconazole against the pathogens were (0.7881 ± 0.3153) μg/mL and (0.0886 ± 0.1453) μg/mL, respectively. There was no significant correlation between the sensitivity of the isolates to fludioxonil, carbendazim and tebuconazole. The results of greenhouse trials showed that the control efficacy of fludioxonil suspension seed coat agent could reach 58.00% (75.0 μg a.i/g) in 2020 and 63.69% (50.0 μg a.i/g) in 2021 when used to treat wheat as a seed dressing agent. The results of this study provide the basis for the rational use of fludioxonil in the control of wheat crown rot and provide information for monitoring the sensitivity of pathogenic fungi to fungicides.