Sensitivity of the isolates of Fusarium pseudograminearum to carbendazim in Henan Province

Wheat stem rot caused by Fusarium pseudograminearum has become the main disease in Huang-Huai wheat area, which poses a great threat to the stable and high yield of wheat. In order to detect the sensitivity to carbendazim of F. pseudograminearum causing wheat stembase rot in Henan Province, China, 90 isolates of were collected from 8 counties in 2019, the inhibitory activities of these isolates were determined by mycelial growth rate method. The results were analyzed by variance analysis and cluster analysis, and the sensitivity of tebuconazole and fludioxonil was also tested, to analyze the correlation efficient existed between carbendazim and the two fungicides, tebuconazole and fludioxonil. The results showed that the minimum inhibitory concentration of carbendazim was 2.4 μg/mL, the EC₅₀ values ranged from 0.436 to 1.73 μg/mL, the maximum value was 3.98 times the minimum value, and the average EC₅₀ value was (0.750 ± 0.291) μg/mL. The sensitivity frequency distribution map showed that although there were subpopulations with low sensitivity to multiple bacteria, there were still 61 strains tested within the corresponding main peak range, and the sensitivity frequency distribution was a continuous single peak curve, which could be used as the sensitivity baseline of the pathogen to carbendazim. The results of variance analysis showed that the sensitivity of the different county to carbendazim was less different, and the average EC₅₀ value in different cities ranged from 0.604 μg/mL to 1.04 μg/mL, and the lowest and highest strains were Hongqi and Huixian from Xinxiang, respectively, with a difference of 1.72 times. The susceptibility of the strains to carbendazim was significantly different in the same city, and the difference of EC₅₀ value was 3.98 times in Nanyang Neixiang. Cluster analysis showed that there was no significant correlation between the sensitivity of F. pseudograminearum to carbendazem in Henan Province and their geographical origin. There was no significant correlation between the sensitivity of wheat stem rot pathogen to carbendazim and its sensitivity to tebuconazole and fludioxonil. The results of greenhouse control showed that 50% carbendazim wettable powder can be used for wheat seed dressing treatment and the highest control efficacy on wheat stem rot up to 76.66% when the treatment dosage was 3.90 mg/g. The results of this study laid a theoretical foundation for the chemical control of wheat stem rot with carbendazim and provide important information for the sensitivity monitoring of pathogenic bacteria to fungicides.