In order to evaluate the risk of resistance in fungus Fusarium oxysporum from peanuts to hy-mexazol,the sensitivity of 112 F.oxysporum isolates from Shandong Province,Henan Province,Hebei Province,Liaoning Province and Beijing City was determined by mycelial growth inhibition test.Hy-mexazol-resistant mutants were obtained by 20-generation exposure to hymexazol and UV irradiation.Mutants obtained by fungicide adaption and their parent strains were used for assays on their genetic sta-bility,cross-resistance and biological fitness.Results showed that the sensitivity frequency distribution of F.oxysporum isolates presented a unimodal curve close to a normal distribution,and the sensitivity baseline was 37.34 μg/mL.Resistance factor of five hymexazol-resistant mutants obtained by fungicide adaption ranged from 9.21 to 13.16,and the resistance of mutants could be inherited stably for ten gen-erations.Twelve resistant mutants were obtained by UV irradiation,the resistance frequency was 8.57× 10-6.The fitness of resistant mutants obtained by fungicide adaption was lower than that of their parent strains.Besides,there was no cross-resistance between hymexazol and carbendazim,prothioconazole or pyraclostrobin.The above results suggest a low to moderate risk level of resistance in F.oxysporum to hymexazol.When using hymexazol for the control of peanut root rot,it is recommended that it should be used in rotation with fungicides with no or negative cross-resistance in the pathogen to control the de-velopment of resistance in the field.
维普
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