The Sensitivity and Resistance Risk Assessment of Coniella vitis to Mefentrifluconazole

Abstract

Coniella vitis, one important fungal pathogen, causes grape white rot which can significantly reduce yield and quality of grape. Fungicide application is the main control measure of grape white rot. To evaluate the resistance and risk of C. vitis in Shandong province to mefentrifluconazole, in this experiment, the sensitive baseline of C. vitis to mefentrifluconazole was established, and resistance risk of the pathogen was evaluated by analyzing the genetic stability, biological characteristics, and interaction resistance with other fungicides of the mefentrifluconazole resistant strain. The field evaluation suggested that mefentrifluconazole is an excellent fungicide for control of C. vitis on grape. The EC50 of 76 strains of C. vitis to mefentrifluconazole was ranged from 0.0210 to 59.0305 μg/mL. The frequency distribution map of EC50 of 64 strains of C. vitis in the first main peak against mefentrifluconazole compound normal distribution, the average EC50 is 0.7409±0.4346 μg/mL, which can be used as the sensitive baseline for C. vitis in Shandong province to mefentrifluconazole. There had resistant isolates to mefentrifluconazole emerged in the field, sharing for 3.95% of the total tested strains. No difference was observed between the resistant and sensitive strains in terms of temperature sensitivity. The average rate of mycelial growth, spore production and pathogenicity of resistant strains did not decrease compared to sensitive strains, and some resistant strains were even higher than sensitive strains. The correlation coefficent of the logarithms of EC50 values to C. vitis between mefentrifluconazole and other fungicides, including pyraclostrobin, thiram, mancozeb, carbendazol, imazalil, difenoconazole, propiconazole and tebuconazole, were -0.0812, 0.1024, -0.2865, -0.2178, 0.3198, 0.5598, 0.5511 and 0.3977. Indicating that there was no significant cross resistance between mefentrifluconazole and the above 8 fungicides. This study lays a foundation for the resistance risk assessment of C. vitis to mefentrifluoconaole.