Cross-Resistancepatternsand Multiple-resistance Patterns To Fenoxaprop-P-ethyl-resistance Alopecurus Japonicus Associated With Different Mutations

Alopecurus japonicus,a widespread annual or biennialgrass weed,occurs in a majority of wheat and oilseed rape planting areas in Yangtze River Valley.Up to now,fenoxaprop-P-ethyl,isoproturon and mesosulfuron-methyl aremain herbicides used to control grass weeds including A.japonicus in fields,among which fenoxaprop-P-ethyl is one of the most important chemical agents for controlling A.japonicus inChina for many years.Frequent use of fenoxaprop-P-ethyl has led to the development of resistance in many A.japonicus populations.Six kinds of amino acid substitutions of Acetyl-CoA carboxylase(ACCase)referring to fenoxaprop-P-ethylresistance inA.japonicus have been testified including I1781L,W1999C,W1999L,W2027C,I2041N and D2078G.In this study,cross-resistance and multiple-resistance patterns offenoxaprop-P-ethyl-resistantA.japonicus with three sorts of ACCase mutations(I1781L,I2041Nand D2078G)were tested.Main results are:Thefenoxaprop-P-ethyl-resistant A.japonicus with three sorts of ACCase mutations(I1781L,I2041Nand D2078G)expressed cross-resistance to the APP herbicides(haloxyfop-R-methyl,clodinafop-propargyl,fluazifop-P-butyl and quizalofop-P-ethyl).Thefenoxaprop-P-ethyl-resistant A.japonicus with I1781L mutation had middle resistance to CHD herbicide(sethoxydim),and the resistance indices(RI)was 29.48.The JZJR-1 population with I2041N mutation was only resistant to APP herbicides,without cross-resistance to theCHD herbicide(sethoxydim and clethodim)and PPZ herbicide(pinoxaden).The JCWJ-3 population with D2078G mutation expressed cross-resistance to the APP herbicides(haloxyfop-R-methyl,clodinafop-propargyl,fluazifop-P-butyl,quizalofop-P-ethyl),CHD herbicide(sethoxydim,clethodim)and PPZ herbicide(pinoxaden),and the RIs were 10.17,61.97,68.42,20.49,112.10,43.98 and 24.85,respectively.The AHFD-3 and JCWJ-3 population have the same mutation of D2078G of ACCase,while JCWJ-3 population had higher resistance to all tested ACCase-inhibiting herbicides.The JCJT-2 and JCJT-3 population have the same mutation of I1781L of ACCase,while the RIs of JCJT-2 was higher than those of JCJT-3 to all tested ACCase-inhibitingherbicides.The results implied that the higher resistance to fenoxaprop-P-ethyl,the higher cross-resistance to other ACCase-inhibiting herbicides.Thefenoxaprop-P-ethyl-resistant A.japonicus with three sorts of ACCase mutations(I1781L,I2041N and D2078G)didn't expressedmultiple-resistance to mesosulfuron-methyl,chlorotoluron and glyphosate.The fenoxaprop-P-ethyl-resistant A.japonicus with I1781L mutation didn't expressed multiple-resistance to flucarbazone-sodium and pyroxsulam.The JZJR-1 population with 12041N mutation was only expressed low resistant topyroxsulam,and the RI was 4.67.The population of AHFD-3 and JCWJ-3 with D2078G mutation had low resistant to flucarbazone-sodium,and the RIs were 4.87 and 6.73 respectively.Therefore,we could use mesosulfuron-methyl,chlorotoluron and glyphosate to prevent the fenoxaprop-P-ethyl-resistant A.japonicus with three sorts of ACCase mutations(I1781L,I2041N and D2078G).We also should avoid use pyroxsulam to prevent the fenoxaprop-P-ethyl-resistant A.japonicus population with 12041N mutation for a long time.Besides this,we should use flucarbazone-sodium propely to prevent the fenoxaprop-P-ethyl-resistant A.japonicus population with D2078G mutation.It was important to delay the strengthening of resistance to resistant A.japonicus population.