• The Korean Journal of Pesticide Science
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• v.21 no.1
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• pp.42-48
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• 2017

This study was conducted to compare the effect of bagging technique on the presence of pesticide residues in various parts of grape fruit (whole fruit, pulp and peel). The tested pesticides were diluted at 2,000 times and sprayed three times onto the crops at an interval of seven days and then they were collected at 0, 1, 3, 5 and 7 days after final application. Later, bagging/non-bagging samples were pre-treated with fruit, pulp and peel samples, respectively. Thiacloprid and lufenuron were not detected in any of the bagging samples. The thiacloprid residues of non-bagging samples in whole, peel and pulp samples were 0.47-1.09, 0.18-0.33 and 1.24-1.67 mg/kg, respectively. The lufenuron residues of non-bagging samples in whole fruit, peel and pulp samples were 0.16-0.62, < LOD-0.08 and 0.85-1.48 mg/kg, respectively. The biological half-lives of thiacloprid and lufenuron in whole fruit, peel and pulp of non-bagging samples were 5.7, 15.1 and 7.8 days and 4.0, 9.4 and 2.6 days, respectively. While the unbagged samples showed a sequential decrease in pesticide residues, this study concludes that bagging would be an effective method to protect the presence of thiacloprid and lufenuron residues in grape fruits.

• Korean journal of applied entomology
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• v.33 no.3
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• pp.201-206
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• 1994

Trunk implantation method of phosphamidon 50% Lq.is commonly applied to control the pine needle gall midge (Thecodiplosis laponensts Uchida et Inouye) Since trunk implantaion is normally practiced during the late Spring, it is often difficult to accommodate necessay labor in mral area. As an alternative, aerial spraylng of less toxic ~nsecticide was designed. Usage of less toxic insecticide in the aenal control of pine needle gall midge can reduce the damage to forest ecosystem. The buproferin, one of the insect growth regulator, was selected at d~fferent rate of dilutions and the treatments effects ruere evaluated at different date and time When 50 t~mes diluted solution of buprofezin 40% SC was treated on different period, there was no significant difference in dficacies. the control efficacies of buproferin 40% SC was measured by occurrences (%) of gall formation of the pine needle gall midge using a ultra low volume (ULV) sprayer and the dilutions of 10X 30X and 50X of buprofez~n 40% SC gave efficacies. 72.4. 57.6 and 8.4, respectively.

• The Korean Journal of Pesticide Science
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• v.18 no.4
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• pp.269-277
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• 2014

The multiclass pesticide multiresidue method for the simultaneous determination of diflubenzuron in agricultural products was conducted by using HPLC-UVD. The method was validated through the guidelines of linearity, specificity, limit of detection (LOD), limit of quantification (LOQ), accuracy and precision with pesticide-free spinach, Korean cabbage, eggplant, squash, sweet pepper, cucumber, Korean melon. The calibration curve of diflubenzuron was linear over the concentration range of 0.05-5 mg/kg with correlation coefficient of above 0.99999. The limit of detection and quantification was 0.008 and 0.02 mg/kg. Mean recoveries of diflubenzuron for each sample were 77.5-105.6%. Relative standard deviation (RSD) in recoveries were all less than 20%. The intra-day and inter-day precision (RSD) were 0.4-1.9% and 0.7-1.9%, respectively. The result of validation indicated that this method was accurate and rapid assay.

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

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

• The Korean Journal of Pesticide Science
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• v.12 no.1
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• pp.67-73
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• 2008

The dissipation patterns of a boscalid in cucumber under greenhouse condition was investigated to establish pre-harvest residue limit (PHRL) and biological half-life. Initial concentration of boscalid in cucumber at standard application rate was $7.29\;mg\;kg^{-1}$ and decreased to $0.04\;mg\;kg^{-1}$ after 15 days with half-life of 1.9 day, while the initial concentration was $14.69\;mg\;kg^{-1}$ and decreased to $0.11\;mg\;kg^{-1}$ after same period with half lift of 2.0 day at double application rate. PHRL was suggested by prediction curve derived from the decay curve of boscalid at double rate treatment. For example, $10.39\;mg\;kg^{-1}$ was calculated for 10 days before harvest, and $1.73\;mg\;kg^{-1}$ for 5 days. Dilution effect was major factor far the decrease of boscalid residue due to fast increasement of weight of cucumber during cultivation. Final residues level of boscalid was predicted based on the dissipation curve and guideline on safe use, when boscalid was used to control powdery mildew and gray mold. At standard rate application, $1.26\;mg\;kg^{-1}$ and $1.33\;mg\;kg^{-1}$ were calculated as final residue levels for control powdery mildew and gray mold, respectively, which are above the MRL(Meximum Residue Limit).

• The Korean Journal of Pesticide Science
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• v.17 no.4
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• pp.435-439
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• 2013

Bacillus amyloliquefaciens M27 was selected as a control agent for the biological control of cucumber powdery mildew. The new mixture of B.amyloliquefaciens M27 and plant (Eucalytus) extract was developed to improve the control activity of B.amyloliquefaciens M27 against cucumber powdery mildew. The mixed formulation showed the high preventive and curative control effect against cucumber powdery mildew when it was diluted at 500 times and foliar-sprayed. Its control effect was higher in preventive spraying than curative spraying. When 500-fold diluted solution of the formulation was sprayed preventively four times at five-day intervals, three times at seven-day intervals and twice at ten-day intervals, the diseased leaf area was shown to be 4.4%, 8.0%, 27.9%, respectively; Whereas the diseased leaf area in the control plot was 45.4%. When the 500-fold diluted formulation was sprayed curatively four times at five-day intervals, three times at seven-day intervals and twice at ten-day intervals after occurred cucumber powdery mildew, the diseases leaf area was 11.5%, 25.2%, 51.8%, respectively; whereas in the control plot, the diseases leaf area was 64.3%. When the 500-fold diluted formulation was treated four times at five-day intervals in the plastic house, its control effect was higher than that treated three times at seven-day intervals and twice at ten-day intervals. As the results, the mixed formulation of B.amyloliquefaciens M27 and plant extract could be a promising candidate of bio-fungicides for the environment-friendly control of powdery mildew of cucumber.

• The Korean Journal of Pesticide Science
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• v.21 no.1
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• pp.17-25
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• 2017

Dissipation pattern and biological half-lives of fungicides boscalid and pyraclostrobin were calculated on jujube. The pesticides were sprayed on jujube in two different field at the standard rate, respectively. The raw agricultural commodities were harvested at 0 (2 hr), 1, 3, 5, 7, 10 and 14 days after treatment, and analyzed by HPLC/DAD. The method limit of quantification (MLOQ) was $0.02mg\;kg^{-1}$ for boscalid and pyraclostrobin. The recovery ranged 101.8~109.3% with below 5% of CV (Coefficient of variation) for boscalid and 104.2~115.4% with below 5% of CV for pyraclostrobin. An average initial deposit at field 1 and field 2 samples were observed 0.40 and $0.48mg\;kg^{-1}$ for boscalid and, 0.76 and $0.57mg\;kg^{-1}$ for pyraclostrobin, respectively. The biological half-lives of field 1 and field 2 were 11.0 and 13.2 day for boscalid, and 6.1 and 12.7 days for pyraclostrobin.

• Research in Plant Disease
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• v.23 no.3
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• pp.268-277
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• 2017

Fusarium head bight (FHB) is a devastating disease on major cereal crops worldwide which causes primarily by Fusarium graminearum. Synthetic fungicides are generally used in conventional agriculture to control FHB. Their prolonged usage has led to environmental issues and human health problems. This has prompted interest in developing environmentally friendly biofungicides, including botanical fungicides. In this study, a total 100 plant extracts were tested for antifungal activity against F. graminearum. The crude extract of Pterocarpus santalinus heartwood showed the strongest antifungal activity and contained two antifungal metabolites which were identified as ${\alpha}$-cedrol and widdrol by GC-MS analysis. ${\alpha}$-Cedrol and widdrol isolated from P. santalinus heartwood extract had 31.25 mg/l and 125 mg/l of minimal inhibitory concentration against the spore germination of F. graminearum, and also showed broad spectrum antifungal activities against various plant pathogens. In addition, the wettable powder type formulation of heartwood extract of P. santalinus decreased FHB incidence in dose-dependent manner and suppressed the development of FHB with control values of 87.2% at 250-fold dilution, similar to that of chemical fungicide (92.6% at 2,000-fold dilution). This study suggests that the heartwood extract of P. santalinus could be used as an effective biofungicide for the control of FHB.

• The Korean Journal of Pesticide Science
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• v.19 no.3
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• pp.329-334
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• 2015

With 86 isolates of Botrytis cinerea obtained from diseased fruits of tomato, strawberry and cucumber, it was conducted to detect the fungicide resistance of B. cinerea against mepanipyrim through an agar dilution method. FGA medium was used for monitoring the resistance. Among 86 isolates of B. cinerea, resistant isolates were composed by 23.3%, which was different according to regions isolating the pathogen. In accordance with isolation region, the isolation frequency of resistant isolates was as follows; that of Gyeonggi, Gyeongnam/Pusan and chungnam was 28.6%, 33.3% and 12.8%, respectively. The resistant isolates of B. cinerea showed the cross resistance between mepanipyrim and pyrimethanil. Also the pathogenicity of B. cinerea resistant to mepanipyrim was high as like that of sensitive isolates. Because of them, it should be necessary to manage the spraying system of mepanipyrim and the monitoring for the fungicide resistance.