• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.48 no.5
• /
• pp.402-406
• /
• 2003

Greenhouse and laboratory studies were conducted to determine the allelopathic potentials of extracts or residues from sweet potato (Ipomoea batatas L. (Lam). The extracts applied on filter paper in a Petri dish bioassay significantly inhibited root growth of alfalfa. Aqueous leachates at 40g dry tissue $\textrm{L}^{-1}$ (g $\textrm{L}^{-1}$) from leaves showed the highest inhibition against alfalfa, and followed by stems and roots. Alfalfa root growth was significantly inhibited by methanol extracts of the same plants as the concentration increased. The effect of residue incorporation into soil on seedling growth of com, soybean, barnyard grass and eclipta was examined in the greenhouse, and results showed that the leaf residues at 200g $\textrm{kg}^{-1}$ by plant parts inhibited shoot dry and root dry weights of test plants by 60-80%. By means of HPLC, causative allelopathic substances present in plant parts of sweet potato "Sinyulmi" were identified as coumarin, trans-cinnamic acid, o-coumaric acid, p-coumaric acid, and chlorogenic acid. Total content of these compounds for leaves extracts were detected as the greatest amount in EtOAc fraction, especially trans-cinnamic acid was the greatest component. These results suggest that sweet potato plants have herbicidal potentials, and that their activities exhibit differently depending on plant parts.ant parts.

• Korean Journal of Environmental Agriculture
• /
• v.37 no.2
• /
• pp.117-124
• /
• 2018

BACKGROUND: Oxycarboxin(5,6-dihydro-2-methyl-N-phenyl-1,4-oxathiin-3-carboxamide-4,4-dioxide) as oxanthiin is a systemic fungicide commonly used for control of various pathogens in agronomic and horticultural crops. In an effort to develop an analytical method to trace the fungicide, a method using HPLC equipped with UVD/MS was studied. METHODS AND RESULTS: Oxycarboxin was extracted with acetone from hulled rice, soybean, Kimchi cabbage, green pepper, and apple samples. The extract was diluted with saline water, followed by liquid-liquid extraction with methylene chloride. Florisil column chromatography was employed for the purification of the extracts. Oxycarboxin was determined on a Zorbax SB-AQ $C_{18}$ column by HPLC with UVD. Accuracy of the proposed method was validated by the recovery tests from crop samples fortified with oxycarboxin at 3 levels per crop. CONCLUSION: Mean recoveries ranged from 78.3% to 96.1% in five representative agricultural commodities. The coefficients of variation were less than 10%, and limit of quantitation of oxycarboxin was 0.04 mg/kg. A confirmatory technique using LC/MS with selected-ion monitoring was also provided to clearly identify the suspected residue. The method was reproducible and sensitive to determine the residue of oxycarboxin in agricultural commodities.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.38 no.3
• /
• pp.156-164
• /
• 2018

Pesticide application in agriculture provides significant benefits such as protection from disease, prevention of harmful insects, and increased crop yields. However, accurate toxicological tests and risk assessments are necessary because of many related adverse effects associated with pesticide use. In this review, we discuss and analyze residual pesticides contained in livestock feed in Korea. A pesticide residue tolerance standard for livestock feed has not been precisely established; so, risk assessments are required to ensure safety. Standards and approaches for animal criteria and appropriate methods for evaluating residual pesticides are discussed and analyzed based on technology related to animal product safety in Korea. The safety of livestock feed containing pesticides is assessed to establish maximum residue limits relative to pesticides. Analysis of residual pesticides in milk, muscle, brain, and fat was performed with a livestock residue test and safety evaluation of the detected pesticide was performed. Efficacy of organic solvent extraction and clean-up of feed was verified, and suitability of the instrument was examined to establish if they are effective, rapid, and safe. This review discussed extensively how pesticide residue tolerance in livestock feed and hazard evaluation may be applied in future studies.

• Korean Journal of Environmental Agriculture
• /
• v.39 no.2
• /
• pp.122-129
• /
• 2020

BACKGROUND: Dissipation patterns of insecticides (acequinocyl, clothianidin, diflubenzuron, thiacloprid, and thiamethoxam) on strawberry grown in plastic-covered greenhouse were evaluated at 7 intervals including the preharvest interval after application. This study was performed to determine the residue concentrations, half-lives and dissipation rates in strawberry for the harvest periods. METHODS AND RESULTS: Acequinocyl, clothianidin, diflubenzuron, thiacloprid, and thiamethoxam were applied in accordance with critical good agricultural practices for strawberry. Strawberry samples were collected at 0, 1, 2, 3, 5, 7 and 10 days after application. Quantitaion was performed by HPLC/DAD and HPLC-MSMS system with C₁₈ column. The limit of quantitation (LOQ) values varied between were 0.00025~0.05 mg/kg on strawberry. The recoveries of acequinocyl, clothianidin, diflubenzuron, thiacloprid and thiamethoxam at two concentrations ranged from 70.9~104.9% on strawberry. The half-lives of pesticide dissipation on strawberry for two fields ranged from 1.3~8.2 days. The dissipation rates were evaluated according to the statistics method with a 95% confidence. CONCLUSION: The residue levels of insecticides (acequinocyl, clothianidin, diflubenzuron, thiacloprid, and thiamethoxam) on strawberry at 0-day after application were below the specified values by Korean MRL. To estimate dissipation rate constant of pesticides on crop for harvest periods, it is important to set the pre-harvest residue limit for human health and consumer protection in Korea.

• The Korean Journal of Pesticide Science
• /
• v.9 no.4
• /
• pp.359-364
• /
• 2005

Comparison of pesticide residue dissipation in/on cucurbitaceous fruit vegetables applied by foliar spraying under greenhouse was carried out to give information on crop grouping for assessment of pesticide risk. Even though the initial deposit of spayed pesticide on the target vegetables were somewhat different from the varieties, the dissipation patterns of the residues gave a similar tendency. In case sub-groupings of cucurbitaceous fruit vegetables are carefully arranged, the residue data among the vegetables are able to be taken for pre-harvest interval (PHI) settings or food safety assessment.

• Korean Journal of Environmental Agriculture
• /
• v.42 no.3
• /
• pp.193-202
• /
• 2023

Residue monitoring of propiconazole (PCZ) in cabbage, shallot, and spinach was conducted under multi-trial greenhouse conditions. This study aimed to understand the fate of the applied fungicide in these vegetables. Furthermore, the associated health risk of PCZ in leafy vegetables was assessed through dietary risk assessment. Commercially available PCZ (22% suspension concentrate) was administered thrice according to the OECD fungicide application interval guideline. The plant samples were extracted using a slightly modified QuEChERS technique and analyzed using gas chromatography-tandem mass spectrometry. The average PCZ recovery was between 84.5% and 117.6%, with a <5% coefficient of variance. The dissipation of PCZ residue in cabbage, shallot, and spinach after 14 days was 96%, 90%, and 99%, respectively, with half-lives of <5 days. Meanwhile, dietary risk assessments of PCZ residues in the studied vegetables using the risk quotient (RQ) were significant < 100 (RQ < 100). Thus, the population groups considered in this study were not at substantial risk from consuming leafy vegetables sprayed with PCZ following critical, good agricultural practices.

• Korean Journal of Medicinal Crop Science
• /
• v.15 no.3
• /
• pp.220-226
• /
• 2007

For the analysis of hazard factors and the development of GAP (Good Agricultural Practices) Ginseng, 10 ginseng cultural farms wished certified GAP were selected at Geumsan-gun area, a representative site of ginseng cultivation in Korea. In order to verify the safety of GAP ginseng, possible contamination of pesticide and heavy metal residues, and microbial hazard were analyzed. Soil and water around ginseng cultivation field, and ginseng were investigated. Eighty-one pesticides including carbendazim were used as typical pesticide against plant pathogens and insect pests of ginseng plant and general crops. There was no excess the maximum residue limit (MRL) in residue figure of the soil. Including the residue figure of the arsenic (0.81 ml/kg) and 7 other heavy metals was also suitable to cultivate the ginseng plant. The irrigation water and dilution water for pesticide application were also safety level for GAP. Fresh ginsengs from the farms were sampled and investigated pesticide residues and contaminations of bacteria. Among 23 pesticides tested, we didn't detect any kinds of pesticide residues, but tolclofos-methyl was frequently found in the other ginseng field. On the investigation of microorganism hazards, 2 gram negative bacteria and 1 gram positive bacterium were found in the fresh ginseng. Number of total bacteria was $1.5{\times}10^3$ cfu/ml, which was less than the other agriculture products. At these results, 10 selected ginseng farms were good cultural places for GAP ginseng production and the ginseng cultured from Geumsan-gun area were a good safe far human.

• Korean Journal of Environmental Agriculture
• /
• v.34 no.4
• /
• pp.309-317
• /
• 2015

BACKGROUND: An analytical method was developed using GC-ECD/MS to precisely determine the residue of fipronil, a phenylpyrazole insecticide used to control a wide range of foliar and soil-borne pests.METHOD AND RESULTS: Fipronil residue was extracted with acetone from representative samples of five raw products which comprised hulled rice, soybean, Kimchi cabbage, green pepper, and apple. The extract was diluted with saline water, and fipronil was partitioned into n-hexane/dichloromethane (20/80, v/v) to remove polar co-extractives in the aqueous phase. Florisil column chromatography was additionally employed for final purification of the extract. Fipronil was separated and quantitated by GC-ECD using a DB-17 capillary column. Accuracy of the proposed method was validated by the recovery from crop samples fortified with fipronil at 3 levels per crop in each triplication.CONCLUSION: Mean recoveries ranged from 86.6% to 106.0% in five representative agricultural commodities. The coefficients of variation were less than 10%. Limit of quantitation of fipronil was 0.004 mg/kg as verified by the recovery experiment. A confirmatory technique using GC/MS with selected-ion monitoring was also provided to clearly identify the suspected residue. Therefore, this analytical method was reproducible and sensitive enough to determine the residue of fipronil in agricultural commodities.

• Horticultural Science & Technology
• /
• v.34 no.1
• /
• pp.183-194
• /
• 2016

This experiment was conducted to establish an official determination method to measure fluazinam residue in horticultural crops for import and export using GC-ECD/MS. Fluazinam residue was extracted with acetone from fresh samples of four representative horticultural products, the vegetable crops green pepper and kimchi cabbage, and the fruit crops mandarin and apple. The acetone extract was diluted with saline water and n -hexane partitioning was used to recover fluazinam from the aqueous phase. Florisil column chromatography was additionally employed for final purification of the extract. Fluazinam was separated and quantitated by GC with ECD using a DB-17 capillary column. The horticultural crops were fortified with three different concentrations of fluazinam. Mean recoveries ranged from 82.5% to 99.9% in the four crops. The coefficients of variation were less than 10.0%. The quantitative limit of fluazinam detection was $0.004mg{\cdot}kg^{-1}$ in the four crop samples. GC/MS with selected-ion monitoring was also used to confirm the suspected residue. This analytical method was reproducible and sensitive enough to measure the residue of fluazinam in horticultural commodities for import and export.

• Korean Journal of Agricultural Science
• /
• v.37 no.1
• /
• pp.1-6
• /
• 2010

Allelopathic activity of rotation crop residues to common weeds and selectivity of crops were studied for developing an alternative weed control strategy in upland organic farming. All rotation crop residues with various ratios suppressed weed growth, but the growth of crop species stimulated a little when those were grown with the mixture of rotation crop residues except a few crop species. Among the rotation crop residues used in this study hairy vetch was the most effective, followed by Chinese milkvetch, barley and rye in suppression of weed growth. The 90:10 (crop:soil, v/v) treatments incorporation rate of crop residues such as hairy vetch and Chinese milkvetch suppressed completely the growth of all weed species tested in this study. The effect of crop residues on suppression of weed growth reduced to 90% when the incorporation rates decreased to 60% [60:40 (crop:soil, v/v). It was noticed that broadleaf weed species were more susceptible to rotation crop residues than grass weed species. In the influence of crop residues on the crop growth, no growth inhibition was found in red pepper, lettuce and perllia at any incorporation rates, but tomato, cucumber and corn were slightly inhibited in a few cases at their highest incorporation levels. This study demonstrated that rotation crop residues especially hairy vetch and Chinese milkvetch have high herbicidal effects against weeds without inhibiting the growth of crop species.