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目的:研究低毒内吸性杀虫剂吡虫啉在化橘红果实中的残留动态。方法:在化橘红采果前期,树干基部注射吡虫啉可溶性溶液,施药后定期采集化橘红果实,采用高效液相色谱法测定果实中吡虫啉的残留量。结果:以每厘米树干胸径注入0.8mL吡虫啉药剂后,化橘红果实中的农药残留量始终保持在很低的水平;以每厘米树干胸径注入1.5 mL吡虫啉药剂后,前7 d果实中的农药残留量一直在很低的水平,7 d后迅速上升,14 d时达到高峰,之后逐渐下降,30 d降至0.835 mg.kg-1,低于国内和国际上吡虫啉在柑橘类成果中最大残留限量(MRLs≤1 mg.kg-1)。以施用1.5 mL.cm-1吡虫啉药剂对化橘红蛀茎害虫的防治效果最佳。结论:在化橘红果实采收期前30 d,以每厘米树干胸径注入1.5 mL吡虫啉药液,能有效地防治化橘红蛀茎害虫,且果实中的农药残留量始终在安全范围内。
OBJECTIVE: To study the residual activity of imidacloprid, a low toxic systemic insecticide, in orange fruits. Methods: The imidacloprid soluble solution was injected into the trunk at the early stage of the harvesting of the red tangerine fruit. The orange-red fruits were harvested periodically after the application. The residues of imidacloprid in the fruit were determined by high performance liquid chromatography. Results: After injecting 0.8 mL of imidacloprid per centimeter of trunk diameter, the pesticide residues in the orange fruits always kept at a very low level. After injecting 1.5 mL of imidacloprid per centimeter at the DBH, the pesticide residues in the first 7 d The amount of imidacloprid was the highest at the first 7 days and then peaked on the 14th day, then decreased gradually to 0.835 mg.kg-1 on the 30th day, lower than the maximum residue limit of imidacloprid in citrus fruits at home and abroad (MRLs ≤ 1 mg.kg-1). The application of 1.5 mL.cm-1 imidacloprid on the orange-red stem borer pest control effect best. CONCLUSION: Injection of 1.5 mL imidacloprid per centimeter of trunk diameter at the 30th day before the harvested orange fruits can effectively prevent and cure the orange-red stem borer insects, and the pesticide residues in the fruits are always in the safe range.