The Resistance And Resistance Chemical Control Of Japanese Foxtail (Alopecurus Japonicus Steud.) To Haloxyfop-R-Methyl And Its Cross Resistance, Multiple Resistance With Different Herbicides

In this paper, different Japanese Foxtail (Alopecurus japonicus Steud.) populations from the main oilseed rape production area, including Anhui, Shanghai, Zhejiang and Jiangsu were collected and their suspectibility to haloxyfop-R-methyl were determined in laboratory to get an overall understanding on the distribution of resistance population. The resistance level of A. japonicus population collected from different years and their filigal generation were evaluated. Also the resistance level of A. japonicus haloxyfop-R-methyl-resistant population to other aryloxyphenoxy propanoate (AOPP) and cyclohexanedione (CHD) herbicides were evaluated by seed and whole plant bioassay. Toxicity of different herbicides to resistant population were conducted in laboratory to screen effective and low cost herbicides and make mixtures.The resistance level to haloxyfop-R-methyl of different A. japonicus population were evaluated by seed bioassay. The resistance level of A. japonicus population collected from Jintan city xuepingshangyang fallow,which were treated by 50% lethal dose was least and the ED50 was 6.00μg·m-2. The resistance level of A. japonicus population collected from Jurong oilseed rape fields,which were treated by 50% lethal dose was most of all,the ED50 was 1927.64μg·m-2 and the relative resistant level reached 321.27.So we defined the A. japonicus population collected from Jintan city xuepingshangyang fallow was susceptible population and the A. japonicus population collected from Jurong oilseed rape fields was resistant population.It was found that the resistance level of A. japonicus to haloxyfop-R-methyl from different years were increased by years, of which the relative resistant level exceeded 320. The resistance level of untreated progenies of 2007,2008 were close to their parents,,The resistance level of 2007 F1T, which were treated by 50% lethal dose were significantly higher than their parents and untreated progenies (2007F1C), while it was close to that of 2008. The resistance level of 2008 F1T, which were treated by 50% lethal dose, were significantly higher than their parents and untreated progenies (200F1C), and were close to that of 2009. The resistance level of all progenies which were treated by haloxyfop-R-methyl were significantly higher than their parents, which suggested that the resistance level of this A. japonicus biotype to haloxyfop-R-methyl were stable and could be expressed in their progenies.The suspectibility of A. japonicus resistant to haloxyfop-R-methyl to different herbicides were determined by seed and whole plant bioassay. The results revealed that this resistant population was also resistant to some other AOPPs, in which the resistance level was:fluazifop-P-butyl> quizalofop-P-ethyl> fenoxaprop-P-ethyl> clodinafop-propargyl> cyhalofop-butyl. However, a relative low resistance level was observed of this resistant population to cyclohexanedione (CHD) herbicide sharing the same target site with AOPPs, which were agreed with previou studies of our laboratory. Also this resistant population remained to be suspectible to the other herbicides, which had different mode of action.In order to screen out effective herbicides that could be used to control A. japonicus resistant to haloxyfop-R-methyl in oilseed rape fields, the suspectibility of A. japonicus resistant population to ten herbicides belonging to different classes were evaluated by pot experiments. Based on the ED50, the resistant population to ten herbicides was in the following sequence:acetochlor> cyhalofop-butyl> flucarbazone-sodium> clethodim> sethoxydim> fenoxaprop-P-ethyl> trifluralin> clodinafop-propargyl> chlorotoluron> isoproturon. Concerned with the controlling effect and costs, two herbicide mixtures were screened out by Gowing's method. These two herbicide mixtures were clethodim clodinafop-propargyl of 1 : 3 and clethodim:benazolin of 1:5.