kresoxim-methyl and hexaconazole

The dissipation and terminal residues of a fungicide suspension (5% hexaconazole, 25% kresoxim-methyl) in ginseng and soil were investigated by high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). At fortified levels of 0.01, 0.02, and 0.20 mg kg(-1), the recoveries of hexaconazole and kresoxim-methyl were in the range of 80.6∼94.8% and 82.4∼98.8% with relative standard deviation of 3.42-9.12% and 3.19-8.58%, respectively. The half-lives were 7.09-10.73 days in root, 6.80-7.95 days in stem, 5.31-8.49 days in leaf, and 6.30-7.97 days in soil. The terminal residues were all below the maximum residue limits (MRLs) of EU and South Korea. Risk assessment results indicated that the risk of hexaconazole and kresoxim-methyl use in ginseng at dosage of 60-90 g a.i. ha(-1) was negligible to humans. This work would help the government to establish the MRL and provide guidance on the proper and safe use of hexaconazole and kresoxim-methyl in ginseng.

Topics: Chromatography, High Pressure Liquid; Environmental Monitoring; Fungicides, Industrial; Half-Life; Methacrylates; Panax; Pesticide Residues; Phenylacetates; Plant Leaves; Plant Roots; Plant Stems; Republic of Korea; Soil; Soil Pollutants; Strobilurins; Tandem Mass Spectrometry; Triazoles

Although there is some evidence regarding the effect of solarization and biosolarization on pesticide degradation, information is still scarce. The aim of this study was to determine the effect of these disinfection techniques on the degradation of eight fungicides (azoxystrobin, kresoxin methyl, tebuconazole, hexaconazole, triadimenol, cyprodinil, pyrimethanil and fludioxonil) commonly used in pepper crops under greenhouse cultivation. Seventy-five 17-L pots filled with clay-loam soil were placed in a greenhouse during the summer season and then contaminated with the studied fungicides. Treatments consisted of different disinfection treatments, including a control without disinfection, solarization and biosolarization. For the solarization and biosolarization treatments, low-density polyethylene film was used as cover. Five pots per treatment were sampled periodically up to 90d after the beginning of each treatment and fungicide residues were analyzed by GC/MS. The results showed that both solarization and biosolarization enhanced fungicide dissipation rates with regard to the control treatment, an effect which was attributed to the increased soil temperature. Most of the fungicides studied showed similar behavior under solarization and biosolarization conditions. However, triadimenol was degraded to a greater extent in the biosolarization than in the solarization treatment, while fludioxonil behaved in the opposite way. The results confirm that both solarization and biosolarization contribute to pesticide dissipation and can therefore be considered alongside other soil disinfection techniques, as a bioremediation tool for pesticide-polluted soils.

Topics: Dioxoles; Environmental Restoration and Remediation; Fungicides, Industrial; Hot Temperature; Methacrylates; Phenylacetates; Photochemical Processes; Pyrimidines; Pyrroles; Soil; Soil Pollutants; Strobilurins; Triazoles