• Korean Journal of Environmental Agriculture
• /
• v.16 no.4
• /
• pp.285-290
• /
• 1997

This study was conducted to develop labor-saving pesticide-fertilizer mixed formulation through a single application of mixed formulation of an insecticide imidacloprid coated on a slow release urea. The release of both total nitrogen and imidacloprid into water was delayed with increasing adhesive.Imidacloprid was released out 95% within 24 hours, whereas total nitrogen released in mixed formulation until 40 days was released less extent by increasing adhesive. There was no difference between pesticide-fertilizer mixed formulation and coated urea thereafter. The content of $NH_4-N$ in the soil treated with pesticide and urea seperating was higher until 10 days but gradually decreased compare to that of pesticide-fertilizer mixed formulation or coated urea. The population density of nitrate reducing bacteria and denitrifying bacteria in soil after treatment were lower in the pesticide-fertilizer mixed formulation and coated urea than those of pesticide and urea separate treatment. The residue of imidacloprid in soil was slightly higher in the treatment of pesticide alone than the pesticide-fertilizer mixed formulation and pesticide and urea seperating treatment. The population and control efficacy of small brown planthopper, Laodelphax striatellus, were not significance different among treatments.

• The Korean Journal of Pesticide Science
• /
• v.12 no.1
• /
• pp.74-81
• /
• 2008

To elucidate the exposure of pesticide in agricultural environment and to investigate distribution of pesticide in paddy fields. This experiment was carried out to clarify pesticide distribution in paddy fields applied with different formulations and growing stages. Initial dissipation rate of applied butachlor EW and oxadiazon EC before rice planting were more than 90% within 3 days in paddy fields. The distribution of a.i. in the pesticide formulations tested depended upon the elapsed time at each growing stage of rice plant after application. Most of pesticides applied within 15 days after transplanting of rice seedlings, more than 95%, were located in the surface water and soil regardless of pesticides; butachlor, thiobencarb and molinate GR. The distribution of iprobenfos GR, tricyclazole WP and phenthoate EC, after application 2 hours in middle growing stage (46 days after rice planting) were shown as 16.1, 48.9 and 38.9% in surface water, 83.6, 15.4 and 10.7% in soil, and 0.3, 35.7 and 50.4% in rice plants of paddy fields, respectively. Also tricyclazole WP and phenthoate EC, after application 2 hours in the late rice growing stage (90 days after rice planting) were distributed to 7.8 and 9.8% in surface water, and 21.7 and 5.1% in soil, and 70.5 and 85.1% in rice plants of paddy fields, respectively.

• Journal of Food Hygiene and Safety
• /
• v.25 no.2
• /
• pp.91-99
• /
• 2010

Two pesticides commonly used in spinach were subjected to a field residue trial to ensure safety of terminal residues in the harvest. The residual patterns of two pesticides, which were Azoxystrobin and chlorpyrifos were examined after applying with the recommended dose and their $DT_{50}$ were calculated. Also degradation patterns of pesticides at storage $4^{\circ}C$ were compared to those at $20^{\circ}C$, and removal rates of pesticides by washing spinach with water were measured. Biological half-lives of azoxystrobin and chlorpyrifos were 3.2~3.8 and 3.8~4.7 days, respectively. During the storage period, the degradation patterns were appeared more obviously at $20^{\circ}C$ than $4^{\circ}C$. Removal rates of azoxystrobin and chlorpyrifos were 9.6~90.0% and 17.7~85.8% by various washing methods.

• The Korean Journal of Pesticide Science
• /
• v.17 no.4
• /
• pp.307-313
• /
• 2013

This study was carried out to investigate the residual characteristics of fungicide azoxystrobin and difenoconazole in Prunus mume fruits, and establish pre-harvest residue limits (PHRL) based on dissipation and biological half-lives of fungicide residues. The fungicides were sprayed onto the crop at recommended dosage once and 3 times in 7 days interval, respectively. The samples were harvested at 0, 1, 2, 4, 6, 8, 10, 12 and 14 days after treatment. These residual pesticides were extracted with QuEChERS method, clean-up with $NH_2$ SPE cartridge, and residues were analyzed by HPLC/DAD and GLC/ECD, respectively. Method quantitative limits (MQL) of azoxystrobin were 0.03 mg $kg^{-1}$ and of difenoconazole were 0.006 mg $kg^{-1}$. Average recovery were $93.2{\pm}2.49%$, $85.5{\pm}1.97%$ for azoxystrobin at fortification levels at 0.3 and 1.5 mg $kg^{-1}$, and $100.8{\pm}6.74%$, $87.6{\pm}9.92%$ for difenoconazole at fortification levels at 0.06 and 0.3 mg $kg^{-1}$, respectively. The biological half-lives of azoxystrobin were 5.9 and 5.2 days at recommended dosage once and 3 times in 7 days interval, respectively. The biological half-lives of difenoconazole were 9.3 and 8.0 days at recommended dosage once and 3 times in 7 days interval, respectively. The PHRL of azoxystrobin and difenoconazole were recommended as 5.32 and 1.64 mg $kg^{-1}$ for 10 days before harvest, respectively.

• Journal of Food Hygiene and Safety
• /
• v.34 no.2
• /
• pp.140-147
• /
• 2019

An analytical method was developed for the determination of quinoxyfen in agricultural products using the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The samples were extracted with 1% acetic acid in acetonitrile and water was removed by liquid-liquid partitioning with $MgSO_4$ (anhydrous magnesium sulfate) and sodium acetate. Dispersive solid-phase extraction (d-SPE) cleanup was carried out using $MgSO_4$, PSA (primary secondary amine), $C_{18}$ (octadecyl) and GCB (graphitized carbon black). The analytes were quantified and confirmed by using LC-MS/MS in positive mode with MRM (multiple reaction monitoring). The matrix-matched calibration curves were constructed using six levels ($0.001-0.25{\mu}g/mL$) and the coefficient of determination ($R^2$) was above 0.99. Recovery results at three concentrations (LOQ, 10 LOQ, and 50 LOQ, n=5) were in the range of 73.5-86.7% with RSDs (relative standard deviations) of less than 8.9%. For inter-laboratory validation, the average recovery was 77.2-95.4% and the CV (coefficient of variation) was below 14.5%. All results were consistent with the criteria ranges requested in the Codex guidelines (CAC/GL 40-1993, 2003) and Food Safety Evaluation Department guidelines (2016). The proposed analytical method was accurate, effective and sensitive for quinoxyfen determination in agricultural commodities. This study could be useful for the safe management of quinoxyfen residues in agricultural products.

• Journal of the Korean Applied Science and Technology
• /
• v.35 no.4
• /
• pp.1213-1223
• /
• 2018

This study was carried out to investigate extraction efficiency by microwave for extraction of pesticide residues and the bioconversion of ginsenosides of ginseng leaf by using various lactic acid bacteria in order to promote the utilization of ginseng leaf. The hexane extraction by microwave of tolclofos-methyl and azoxystrobin in ginseng leaf was efficient. The optimal condition for extraction of tolclofos-methyl and azoxystrobin in ginseng leaf by microwave was 50 to 95 watts of power supply, 3 minutes of extraction.The gisenosides Rg1 and Rb1 contents have decreased, while the Rh1, Rg3, Rk1 and Rh2 have increased due to fermentation. The ginsenosides Rg3 of the fermented ginseng leaf has increased and the contents were $70.62{\sim}77.61{\mu}g/g$(control $2.77{\mu}g/g$). The total phenolic acid content and electron donating ability of the ginseng leaf have totally decreased after 7 days of fermentation. The total phenolic acid contents of the fermented ginseng leaf with various lactic acid bacteria did not show any tendency as different strains.

• Microbiology and Biotechnology Letters
• /
• v.36 no.2
• /
• pp.115-120
• /
• 2008

Bacterial populations from the rhizosphere were obtained and the efficacy of the bacterial wilt suppression, root colonizing ability and resistance to three kinds of chemical pesticides were assayed. According to these results, SKU48-2 was selected as a potential biological agent to control the bacterial wilt caused by Ralstonia solanacearum. SKU48-2 strain at $10^8CFU/ml$ inoculum was able to suppress the bacterial wilt up to 60% in greenhouse trials. Also, the resistance of SKU48-2 to chemical pesticides make possible to use in combination with chemical pesticides for the control of bacterial wilt. Three different powder formulations of SKU48-2 were developed. The shelf-life of powder formulations was effective up to 6 months of storage. Unformulated bacterial suspension could not be stored for 2 weeks, at which time cell viability was completely lost. According to 16S rDNA sequence data, the SKU48-2 stain was identified as Bacillus subtilis.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.6
• /
• pp.375-381
• /
• 2018

This study was performed to investigate the residual characteristics of the insecticide dinotefuran in asparagus under greenhouse conditions from July to August and consequentially to obtain basic data for guidelines on the safe use of this pesticide in asparagus. Residues of dinotefuran in young stem of asparagus before and after growing mother stem were analyzed from samples collected at 0, 1, 3, 5, and 7 days after single application of a commercial formulation of dinotefuran (wettable powder, 10%) at the recommended dose (2,000 times dilution). The residue of dinotefuran in young stem of asparagus was analyzed by HPLC-UVD, and recovery of dinotefuran in young stem was tested at 0.5 and 1.0 mg/kg concentrations. As a result, the limit of quantitation (LOQ) of dinotefuran was 0.01 mg/kg, and the recovery of dinotefuran was in the range of 83.3-94.0% with a coefficient of variation less than 10%. Residues of dinotefuran in young stem of asparagus before and after growing the mother stem were lower than the tentative limit (0.05 mg/kg) from 5 and 3 days after single application, respectively. Based on these results, single application of dinotefuran (wettable powder, 10%) at the recommended dose at 7 days before harvest would have no deleterious effects on safety issues concerning pesticide residue. This result might provide basic information to construct guidelines for the safe use of dinotefuran in asparagus.

• Korean Journal of Environmental Agriculture
• /
• v.14 no.3
• /
• pp.289-295
• /
• 1995

This study was carried out to develop a controlled-release insecticide formulation for the control of rose aphid (Macrosiphum ibarae) in rose and cotton aphid (Myzus persicae) in chrysanthemum (Dendranthema grandiflorum var. Meibung) in greenhouse. Imidacloprid[1-(6-chloro-3-pyridylmethyl)-N-nitroimidazolidin-2-ylideneamine] was chosen as a toxicant. Two synthetic polymers, low density polyethylene(LDPE) and ethylene vinyl acetate(EVA), were used as polymer matrices. The tested plastic sheet formulations were prepared by heat-aided extrusion procedures after mixing imidacloprid technical and the polymers of three different combinations, and physicochemical properties as well as efficacy of the formulations were investigated. The amounts of imidacloprid recovered and incorporated in the formulations were recorded over 90% and 80%, respectively. Release of the active ingredient from the formulations was remarkably affected by mixing rates of polymers. The active ingredient in the formulations was chemically unstable with over 10% degradation rates after 90 day storage at $50{\pm}2^{\circ}C$. The residual amounts of imidacloprid in the soil treated with the formulations were paralleled with the release pattern of the formulations. Efficacy of the formulations on rose and cotton aphid was maintained over 90% even 120days after treatment under greenhouse.

• The Korean Journal of Pesticide Science
• /
• v.12 no.4
• /
• pp.351-356
• /
• 2008

This study was carried out to assess adoptability and environment impacts of ultra low volume (ULV) pesticide spray solutions aerially sprayed by manned-helicopter. Uniformity of the deposited amount in paddy fields was uneven, showing $3.1{\sim}4.7$ times differences among surveyed sites. Drifting distance of aerially sprayed droplets from the target area was within 30 m in the wind direction and 20 m in the opposite direction. Most of the aerially sprayed pesticides were deposited in/on rice plants, while those in submerged paddy water and soil were relatively small. The degradation rate of the deposited pesticides was in the decreasing order of rice plants, paddy water and soil. Soil residues of pesticides in the aerially sprayed rice paddy fields after harvest ranged from non-detected to 0.201 mg/kg. However, no pesticides were detected in brown rice and rice straw. No phytotoxic symtoms were observed in rice plants and nearby non-target crops by the sprayed pesticides.