| Scab of wheat is a worldwide epidemic disease which has seriously threatened the yield and quality of wheat.Chemical pesticides are The major method of prevent to Scab of wheat is chemical pestieides,the key of eontrol effect and reduce the loss of pesticides is strengthening technologies of highly effective and precise drug application.Sudy the control effect and mycotoxin of Scab of wheat with UVA,Mist machine,Self-propelled sprayer and Electric sprayer based on 48%Phenamacril-tebuconazole suspending gagent,to compare the final residue and degradation dynamics of wheat with different spraying machineries,elear way of applying pesticide control effect and the correlation of behavior of pesticide residue.The main research results are as follows:1.The method of detecting pesticides residue of phenamacril and tebuconazole in wheat with GC-MSA method was developed for the multiresidue determination of phenamacril and tebuconazole in wheat plant and grain with GC-MS.Results showed that recoveries of the added standards phenamacril in wheat plant and grain were 78.38-91.91%and 105.14-108.83%at spiked concentrations of 0.05,0.2,and 0.5 mg/kg,and the relative standard deviations(RSDs,%)were 4.27-8.05%and 2.86%-8.40%,the limits of detection(LOQs)were 15.94 and 17.04 μg/kg.The recoveries of the added standards tebuconazole in wheat plant and grain were 88.83-110.41%and 74.84-88.87%,with 2.16%-3.36%and 1.23%-4.73%of RSD the limits of detection(LOQs)were 9.82 and 10.03 μg/kg.The extraction and purification method determined in this experiment has better extraction efficiency and purification effect,and there is no impurity interference in the detection process.The detection method has the advantages of good accuracy,sensitiveness and precision,simple operation,which meets the analysis requirements of pesticide residue.2.The method of detecting content of 5 mycotoxins including DON in wheat with UPLC-MS/MSA method was developed for the multiresidue determination of 5 mycotoxins in wheat grain with UPLC-MS/MS.Results showed that recoveries of the added standards DON,3A-DON,15A-DON,ZEN and OTA in wheat grain were 92.7-97.0%,87.8-94.8%,84.1-102.4%,97.1-98.4%and 96.9-103.2%,at spiked concentrations of 0.02,0.2,and 1.0 mg/kg,and the relative standard deviations(RSDs,%)were 3.4-4.4%,1.8-4.9%,3.1-3.9%,2.5-5.7%and 3.4-7.0%.The detection method has the advantages of good accuracy,sensitiveness and precision,simple operation,which meets the analysis requirements of pesticide residue.The sensitivity of the method was expressed in terms of the limits of detection(LOQs),which were 0.005 mg/L for the 5 mycotoxins.The method has the advantages of simple operation,good recovery,short detection time,good precision,sensitivity and accuracy.3.Effects control of scab of wheat with different spraying machineriesThe experiment was implement according to Pesticide-Guidelines for the Field Efficacy Trials.The results showed that at 24 and 48 g a.i./ha dose,the ear rate of UVA and Mist machine was the lowest,lower than 11.2%.UVA and Mist machine had the significantly increased defense effectiveness on scab of wheat than knapsack electric sprayer,while Self-propelled sprayer had the worst effect.The control effects of UVA,Mist machine,knapsack electric sprayer and Self-propelled sprayer were 82.2-84.8%,78.9-86.8%,71.2-80.7%and 62.6-70.6%.High dose application is beneficial to improve the control effect of scab of wheat,but there was no significant difference.4.Effects of the contents of 5 mycotoxins in wheat grain with different spraying machineriesDetecting the contents of 5 mycotoxin in wheat grain.The results showed that the contents of ZEN and DON can be effectively inhibited by the UVA and Mist machine in a certain concentration range.The inhibitory effect was especially obvious at 2 times the recommended dose(48 g a.i./ha).Compared with blank group,the total amount of DON toxin in wheat grains with UVA and Mist machine was significantly reduced by 76.7%and 91.0%,and the toxin content of ZEN was significantly reduced by 84.0%and 100%.The contents of 5 toxin in wheat grain with UVA and Mist machine all in standards of our country’s develop.5.Effects of different spraying machineries on the total initial deposition of tested pesticides in wheat plantThe total initial deposition of phenamacril and tebuconazole in wheat plant,the results^showed that in a certain concentration range,thJ total initial deposition of pesticides in wheat plants after spraying by UVA and Mist machine was 1.5-3.5 times as much as that after spraying by Self-propelled sprayer.The UVA and Mist machine had the best control effect,which indicated that the control effect was correlated with the total initial deposition of pesticide,and the total initial deposition of pesticide was high,which ensure the effect of pesticide in controlling scab of wheat.6.The study of degradation dynamics and final residues of pesticide residues on wheat with different spraying machineriesUnder the four spraying machineries,the degradation dynamic of phenamacril and tebuconazole in wheat plants conforms to the first-order dynamic equation Phenamacril is relatively slow in digestion and the half-life were 5.775-7.114,3.591-4.500 days with UVA and Mist machine,However,the half-life of phenamacril was 2.398-3.300 dsys with knapsack electric sprayer and Self-propelled sprayer.Tebuconazole had a longer half-life of 4.252-8.250 days compared with phenamacril with different spraying machineries.The result of final residue,in the wheat grain samples,the final residues of phenamacril and tebuconazole were lower than LOQ(0.02mg/kg),it is lower than the minimum pesticide residue limit standard for wheat formulated in China(GB 2763-2016).In consideration of the operational efficiency and food safety,it is suggested to spray 48%Phenamacril-tebuconazole SC to control the scab of wheat,and increase the dosage appropriately to achieve better control effect. |
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