Study On The Efficacy Of Clopyralid Against Weed And Dissipation Dynamics In Beet Field

Sugar beet can not only be used for sugar production,but also as a by-product of sugar production can also be used as a pharmaceutical intermediate to produce drugs,which is an important cash crop in China.Weed hazards in the field are another major constraint limiting sugar beet production in addition to diseases and pests.In recent years,with the increase of sugar beet planting area in China,the planting method of each major producing area has gradually changed to large-scale continuous planting.The effective control of weed and pesticide residues has become the main factor restricting the large-scale development of sugar beet.In this paper,the efficacy of 30%dichloropiclidinic acid water agent on weeds in sugar beet fields and its safety on sugar beet were studied,a residue analysis method of dichloropyridinic acid in sugar beet and soil was established,The final residue on sugar beet and the digestion dynamics on sugar beet plants and soil were studied by this method,which provided theoretical guidance for the safe use of dichloropyridunic acid on sugar beet.The main findings are as follows:1.According to the test guidelines of herbicide for the control of weeds in sugar beet fields,the control effect of 30%dichloropyridinic acid water agent on weeds in sugar beet fields and its safety on sugar beet were studied,as well as the appropriate application dose.The results showed that 30%dichloropiclidinic acid water agent with different application doses had a good control effect on weeds in sugar beet fields,and all the drug treatments had a yield increase effect compared with the blank control,and the yield increase rate was more than 77%.Among them,when the application dose of dichloropyridolic acid was 80 m L/667 m²,the sugar beet leaves had distortion and deformity,and the yield increase rate was slightly lower than that of other treatments.When the application dose is 40～60 m L/667 m²,the prevention effect is good,and the yield increase rate is high,so the recommended dosage of 30%dichloropyridinic acid was 40～60 m L/667 m².2.A method for the detection of residues of dichloropyridinic acid in sugar beet tubers,sugar beet plants and soil samples by Qu ECh ERS method combined with HPLC-MS/MS was established.The results showed that the added concentrations of dichloropicolinic acid in sugar beet tubers,sugar beet plants and soil were 0.05,0.1 and 1 mg/kg,the average recovery rate was between 84.7%～98.2%and the relative standard deviation was between 1.9～18%.The minimum limit of detection（LOD）of dichloropyridinic acid in sugar beet samples is 4.2×10^-4～2.8×10^-4 mg/kg,and the limit of quantification（LOQ）is 0.05 mg/kg,which meets the technical requirements of pesticide residue analysis and detection.3.The residual digestion law of dichloropyriridic acid in sugar beet plants and soil was clarified.the results showed that the digestion dynamics of dichloropyridinic acid in sugar beet plants and soil conformed to the first-order kinetic equation,the half-lives of dichloropyricynic acid in sugar beet plants and soil were 1.5 d and 26.5 d,and the half-life was less than 30 d,respectively,dichloropyridinic acid was an easily degradable pesticide.4.The final residue of dichloropiclidinic acid in sugar beet was determined and administered at a dose of 60 m L/667 m²（270 g a.i./ha）once,The residue of dichloropyridinic acid in sugar beet tubers during harvest was 0.019～0.040 mg/kg,the residue in sugar beet plants was 0.048～0.080 mg/kg and the residue in soil was 0.114～0.371 mg/kg.GB 2763-2021 National Food Safety Standard Maximum Residue Limits of Pesticides in Food stipulates that the maximum residue of dichloropyridinic acid in sugar beet is 2 mg/kg,and the results of this study provide scientific basis and data support for the rational use of dichloropyridolic acid.