Study On The Sensitivity Of Ustilaginoidea Virens To Triazole Fungicides And Strobilurin Fungicide In Liaoning Province

Rice false smut is a fungal disease that occurs in the late stage of rice.In recent years,rice false smut has been widespread in China and has become one of the major diseases of rice.The disease can seriously affect rice yield and rice quality.In this paper,Ustilagunoidea virens was used as the research object and the mycelium growth rate method was used to determine the triazole fungicides(epoxiconazole,tebuconazole,difenoconazole,hexaconazole and diniconazole)in the rice false smut in Liaoning Province in 2017.Sensitive baseline of strobilun fungicides(triclopyricarb,pyraclostrobin,coumoxystrobin,trifloxystrobin and azoxystrobin)Resistance induction was induced,and the growth rate,stability,and cross-resistance with other fungicides were studied after obtaining resistant mutants.The aim is to provide a theoretical basis for the risk assessment,scientific rational use and scientific control of rice blast disease.The main results were as follows:1.Establishment of sensitive baseline of triazole fungicides to Ustilaginoidea virensA total of 78 strains from 8 regions of Liaoning Province were used as test strains.The sensitivity baseline of Ustilagunoidea virens to tebuconazole,difenoconazole,epoxiconazole,hexaconazole and diniconazole was determined by mycelial growth rate method.The results showed that the sensitivity baselines of rice blast fungus to tebuconazole,difenoconazole,epoxiconazole,hexaconazole and diniconazole were 0.0405 μg/m L,0.0780 μg/m L,0.0216μg/m L,0.0292 μg/m Land 0.0928 μg/m L,and there was no significant difference in the sensitivity of rice smut bacteria from different regions to tebuconazole,fluconazole,hexaconazole,epoxiconazole,and diniconazole.2.Establishment of sensitivity baseline of strobilurin fungicides for Ustilaginoidea virensUsing 78 strains from 8 regions of Liaoning Province as test strains,the sensitivity baseline of Ustilagunoidea virens to triclopyricarb,pyraclostrobin,ccoumoxystrobin,trifloxystrobin and azoxystrobin was determined by mycelial growth rate method.The results showed that the sensitivity baselines of Ustilagunoidea virens to triclopyricarb,pyraclostrobin,ccoumoxystrobin,trifloxystrobin and azoxystrobin in Liaoning Province were0.1095 μg/m L,0.0405 μg/m L and 0.3231 μg/m L,0.0508 μg/m L and 0.0170 μg/m L,and there is no significant difference in the sensitivity of the rice blast fungus from different regions to triclopyricarb,pyraclostrobin,ccoumoxystrobin,trifloxystrobin and azoxystrobin.3.Resistance induction of Ustilaginoidea virens to triazole fungicides and specificity of resistance-inducing strainsForty sensitive strains were selected for drug domestication and UV irradiation.Five strains of hexaconazole low-resistant strains were successfully induced and their biological characteristics were studied.The results showed that the growth rate of resistant mutants was significantly reduced.Resistant mutants were not stably inherited;there was no cross-resistance relationship between hexaconazole and epoxiconazole,tebuconazole,difenoconazole,diniconazole4.Resistance induction and resistance-inducing strain specificity of Ustilaginoidea virens to methoxy acrylate fungicidesForty strains of sensitive strains were selected for drug domestication and UV irradiation.Four strains of pyraclostrobin resistance strains were successfully induced and their biological characteristics were studied.The results showed that the growth rate of resistant mutants was significantly decreased.All the four resistant mutants were stable and inherited;there was a cross-resistance relationship between pyraclostrobin and triclopyricarb,ccoumoxystrobin,trifloxystrobin and azoxystrobin.