Study On Residual Dynamics Of Pyraclostrobin·Metiram60%WG In Garlic And Pepper

Garlic and Pepper are universal and valuable vegetable and they are not only rich invitamins but also rich in medicinal properties.60%Pyraclostrobin and metiram WG is used toprotect the plants from damage and infestation by bacteria in garlic and pepper plantingprocess. Garlic and pepper are traditional export vegetable of China. In recent years, with theimprovement of the foreign technical barriers, many countries have stringent requirements on pesticideresidues in garlic and pepper export, which greatly restricted the export of China’s garlic and pepper. Inorder to overcome foreign technical barriers and ensure the food safety of garlic and pepper,an efficient and selective method for analyzing the residues of Pyraclostrobin and metiram ingarlic and pepper was set up. Research on the residue dynamics of Pyraclostrobin andmetiram was carried out to evaluate the impact of using Pyraclostrobin and metiram in garlicfield experiment, so as to reveal the possible approaches of its degradation. This would help toprovide basic information for developing regulations to guard a safe use of Pyraclostrobin andmetiram in garlic fields and to prevent any health problem from consumers.(1).This paper was mainly about the research on dynamic residue and final residue ofPyraclostrobin and metiram in garlic and pepper. The residue and degradation dynamic ofpyraclostrobin and·metiram in garlic and pepper were studied with HPLC for Pyraclostrobinand GC for metiram.(2). The degradation test of60%Pyraclostrobin and metiram WG(the Pyraclostrobin5%,metiram55%) was carried out in garlic fields at two places in two years. The results showedthat the degradation of Pyraclostrobin and metiram followed an equation of one-gradechemical reaction dynamics in the garlic and soils. The degradation half-life of Pyraclostrobinin garli and soil were ranged from2.6d to3.2d and9.0d to10.5d, respectively. Thedegradation half-life of metiram in garlic and soil were ranged from2.8d to3.6d and3.1d to4.1d, respectively.(3). According to the test results carried out at two places in two years, thepyraclostrobin·metiram60%WG were sprayed for3to4successive times at application dose900-1350g a.i./hm2, at7,14,21day after the last application,the final residues ofpyraclostrobin·metiram60%WG in garlic and pepper were lower than0.05mg/kg (MRL). Therefore,preharvest interval was suggested to be7days when pyraclostrobin·metiram60%WG is applied at recommended dosage for garlic.(4). The degradation test of60%Pyraclostrobin and metiram WG was carried out inpepper fields at two places in two years. The results showed that the degradation ofPyraclostrobin and metiram followed an equation of one-grade chemical reaction dynamics inthe pepper and soil. The degradation half-life of Pyraclostrobin in pepper and soil were rangedfrom3.6d to4.4d and8.8d to10.7d, respectively. The degradation half-life of metiram inpepper and soil were ranged from1.6d to2.9d and3.1d to4.4d, respectively.(5). According to the test results carried out at two places in two years, thepyraclostrobin·metiram60%WG were sprayed for3to4successive times at application dose540-810g a.i./hm2, at3,5,7,14,21days after the last application,the final residues ofpyraclostrobin and·metiram in peppe were0.0102～0.2234mg/kg and0.0220～0.0437mg/kg,were lower than0.5mg/kg and1.0mg/kg (MRL), respectively. Therefore,preharvestinterval was suggested to be3days when pyraclostrobin·metiram60%WG is applied atrecommended dosage for pepper.