Monitoring Of Weed Resistance Of Alopecrus L.in Wheat Field In Huanghuaihai Area And Screening Of Effective Control Agents

There are many kinds of weeds in the wheat field,among which Alopecurus aequalis,Alopecurus japonicas and Alopecurus myosuroides are common gramineous weeds in wheat fields in the Huang-Huai-Hai area.In recent years,there have been some reports of failures in chemical weed control in wheat fields.In order to grasp the current status of major weeds resistance in different regions and predict the development trend of resistant weeds,it is essential for real-time monitoring of herbicide resistance.The sensitive baseline is the basis of herbicide resistance monitoring and provides theoretical basis for resistant weed control.Considering the serious resistance of A.aequalis,A.japonicas and A.myosuroides in wheat fields,in this study,the dose-response curve,and relative sensitive baseline of them to different herbicides used in wheat fileds was determined after screening and breeding of sensitive populations.Meanwhile,the resistance levels of some resistant populations of the three weeds were determined by whole-plant dose–response experiments.Also,the herbicides which can effectively control the three resistant weeds were screend by pot method in greenhouse.The main findings are as follows:1.Determination of relative sensitive baselines:Collecting multiple sensitive populations of Alopecurus L.weeds in areas where herbicides have not been used.Screen out the most sensitive population for subculture,and Sensitive strains of three weeds of A.aequalis,A.japonicas and A.myosuroides were obtained.Using the greenhouse potting method,the dose-response curve,GR₅₀0 and relative relative sensitive baseline of A.aequalis,A.japonicas and A.myosuroides to nine herbicides including mesosulfuron-methyl,fenoxaprop-p-ethyl,pyroxsulam,pinoxaden,clodinafop-propargyl,clethodim,iosoproturon,oxadiazon,diflufenican were determined.2.Determination of resistance levels:A total of 46 populations of A.aequalis,A.japonicas and A.myosuroides collected in wheat fields in Shandong,He?nan,Anhui and Jiangsu province was preliminary screened by Mesosulfuron-methyl,Fenoxaprop-p-ethyl,Pyroxsulam,Pinoxaden at field recommended dose by the greenhouse potting method.The dose response curves and resistance levels of the populations to the four herbicides were determined by whole-plant dose–response assay.The results showed that the resistance indexs（RIs）of different A.aequalis population to Mesosulfuron-methyl was significantly different with RIs of 2.80 to 157.79;the RIs to Fenoxaprop-p-ethyl were 11.14 to 234.51;the RIs to Pyroxsulam were 15.43 to 120.53;the RIs to Pinoxaden were 3.35 to 58.09.The populations of A.japonicas also envolved resistance to different herbicides,with RIs of 1.91-146.55 to Fenoxaprop-p-ethyl,RIs of 1.23-76.29 to Mesosulfuron-methyl,RIs of 1.95-28.62 to Pinoxaden,RIs of 2.38-84.43 to Pyroxsulam,respectiviely.Considering A.myosuroides,the RIs to Fenoxaprop-p-ethyl were 10.41-140.16;the RIs to Mesosulfuron-methyl were9.25-79.89 the RIs to Pyroxsulam were 1.69-78.33;the RIs to Pinoxaden was 2.21-92.87.3.Determination of resistance levels by Petri dish method:the shoot growth inhibition rates of above 45 populations of A.aequalis,A.japonicas and A.myosuroides were determined,and the resistance levels were calculated.The results showed that the resistance levels obtained by greenhouse potting method were similar with those obtained by Petri dish method.4.Screening for effective herbicide:the efficacy of five herbicides including isoproturon,clodinafop-propargyl,flufenacet,sulfosulfuron and QYM201 against some resistant population of A.aequalis,A.japonicas and A.myosuroides was determined by potting method in greenhouse.The results showed that the tested weeds had evolved different degrees of resistance to Clodinafop-propargyl and Isoproturon.In order to prevent the further development of weed resistance,and they should not be used alone to control weeds for long term;Flufenacet had a good efficacy against the resistant weed population of A.japonicas and A.myosuroides,whereas had a poor efficacy against A.aequalis.Sulfosulfuron and QYM201showed an excellent efficacy against three resistant weeds,and QYM201 had the higest efficacy.