• Korean Journal of Environmental Agriculture
• /
• v.40 no.2
• /
• pp.99-107
• /
• 2021

BACKGROUND: Pesticide uptake by a rotational crop after being used for the primary crop is a potential cause of violation against the pesticide law if the pesticide is not registered in the secondary crop. This study was conducted to investigate the plant back interval (PBI) of fluopyram for the rotational cultivation of radish. METHODS AND RESULTS: Two experimental approaches were performed the evaluation of residues in radish cultivated successively in soil 16 days after treated with fluopyram onto pepper plant (T1) and in radish cultivated in bare soil treated with fluopyram at PBI 30 and PBI 60 days (T2). A modified QuEChERS method coupled with LC/MS/MS analysis showed good linearity of matrix-matched standard calibration of fluopyram with the coefficient values of determination greater than 0.995. Recovery values at levels of 0.01, 0.05, 0.1 and 0.25 mg/kg ranged from average 84.9 to 117.6% with RSD less than 10%. Fluopyram residues in radish harvested from T1 and T2 were found as levels less than maximum residue limit. CONCLUSION: This study suggests 20~30 days as the PBI of fluopyram for the rotational cultivation of radish in the greenhouse soil treated with fluopyram used for pepper as the primary crop.

• Korean Journal of Environmental Agriculture
• /
• v.29 no.2
• /
• pp.165-175
• /
• 2010

A gas chromatographic (GC) method was developed to determine residues of captan, folpet, captafol, and chlorothalonil, known as broad-spectrum protective fungicides for the official purpose. All the fungicide residues were extracted with acetone containing 3% phosphoric acid from representative samples of five agricultural products which comprised rice, soybean, apple, pepper, and cabbage. The extract was diluted with saline, and dichloromethane partition was followed to recover the fungicides from the aqueous phase. Florisil column chromatography was additionally employed for final cleanup of the extracts. The analytes were then determined by gas chromatography using a DB-1 capillary column with electron capture detection. Reproducibility in quantitation was largely enhanced by minimization of adsorption or thermal degradation of analytes during GLC analysis. Mean recoveries generated from each crop sample fortified at two levels in triplicate ranged from 89.0~113.7%. Relative standard deviations (RSD) were all less than 10%, irrespective sample types and fortification levels. As no interference was found in any samples, limit of quantitation (LOQ) was estimated to be 0.008 mg/kg for the analytes except showing higher sensitivity of 0.002 mg/kg for chlorothalonil. GC/Mass spectrometric method using selected-ion monitoring technique was also provided to confirm the suspected residues. The proposed method was reproducible and sensitive enough to determine the residues of captan, folpet, captafol, and chlorothalonil in agricultural commodities for routine analysis.

• Korean Journal of Food Science and Technology
• /
• v.41 no.6
• /
• pp.722-726
• /
• 2009

The residue distribution ratio of pesticides among the flesh, stem and leaves of hot peppers were investigated to assure the safety of pepper powder and pepper leaves. Mixed solutions of chlorothalonil (wettable powder), kresoximmethyl (water dispersible granules) and procymidone (wettable powder) were applied once onto pepper plants in a plastic film house. After 7 days, the fruits and leaves were harvested and the fruits were divided into the flesh and stems. Pesticide residues in each pepper part were then analyzed by gas chromatography. The results showed that the concentration ratios of the chemicals in the flesh:stem and flesh:leaf ranged from 1:2-5 and 1:11-39, respectively, depending on the chemical evaluated. The observed flesh:stem ratio indicates that the pesticide content of the pepper powder product can increase by 20% if pepper stems are included in the powder product. The Korea Food and Drug Administration does not set a pesticide maximum residue level (MRL) for pepper leaves if a residue ratio in leaves over flesh is more than ten times. Results from this study support non-MRL status on the pepper leaves for the studied pesticides. Additionally, we recommend that the chlorothalonil product of a wettable powder type include the phrase "prohibition of distribution or sale for pepper leaves as food" because chlorothalonil highly resided in pepper leaves as more than twenty-four times that is a criterion level to determine an inclusion of the phrase in the label of pesticide product.

• Proceedings of the Korean Society of Plant Pathology Conference
• /
• 2003.10a
• /
• pp.78.2-79
• /
• 2003

Pepper defensin ( CADEFl) clone was isolated from cDNA library constructed from pepper leaves infected with avirulent strain Bv5-4a of Xanthomonu campestris pv. vesicatoria. The deduced amino acid sequence of CADEFl is 82-64％ identical to that of other plant defensins. Putative protein encoded by CADEFl gene consists of 78 amino acids and 8 conserved cysteine residues to form four structure-stabilizing disulfide bridges. Transcription of the CADEF1 gene was earlier and stronger induced by X campestris pv. vesicatoria infection in the incompatible than in the compatible interaction. CADEF1 mRNA was constitutively expressed in stem, root and green fruit of pepper. Transcripts of CADEFl gene drastically accumulated in pepper leaf tissues treated With Salicylic acid (SA), methyl jasmonate (MeJA), abscisic acid (ABA), hydrogen Peroxide (H$_2$O$_2$), benzothiadiazole (BTH) and DL-${\beta}$-amino-n-butyric acid (BABA). In situ hybridization results revealed that CADEF1 mRNA was localized in the phloem areas of vascular bundles in leaf tissues treated with exogenous SA, MeJA and ABA. Strong accumulation of CADEF1 mRNA occurred in pepper leaves in response to wounding, high salinity and drought stress. These results suggest that bacterial pathogen infection, abiotic elicitors and some environmental stresses may play a significant role in signal transduction pathway for CADEF1 gene expression.

• Korean Journal of Environmental Agriculture
• /
• v.34 no.2
• /
• pp.111-119
• /
• 2015

BACKGROUND: Ethychlozate (ECZ) is a plant growth regulator of synthetic auxin for agricultural commodities (ACs). Accurate and sensitive method to determine ECZ in diverse ACs on global official purpose is required to legal residue regulation. As the current official method is confined to the limited type of crops with poor validation, this study was conducted to improve and extend the ECZ method using high-performance liquid chromatography (HPLC) in all the registered crops with method verification. METHODS AND RESULTS: ECZ and its acidic metabolite (ECZA) were both extracted from acidified samples with acetone and briefly purified by dichloromethane partition. ECZ was hydrolyzed to form ECZA and the combined ECZA was finally purified by ion-associated partition including hexane-washing. The instrumental quantitation was performed using HPLC/ FLD under ion-suppression of ECZA with no interference by sample co-extractives. The average recoveries of intra- and inter-day experiment ranged from 82.0 to 105.2% and 81.7 to 102.8%, respectively. The repeatability and reproducibility for intra- and inter-day measurements expressed as a relative standard deviation was less than 8.7% and 7.4%, respectively. CONCLUSION: Established analytical method for ECZ residue in ACs was applicable to the nation-wide pesticide residues monitoring program with the acceptable level of sensitivity, repeatability and reproducibility.

• Korean Journal of Food Science and Technology
• /
• v.16 no.4
• /
• pp.418-422
• /
• 1984

In order to determine the removal efficiency of pesticide residues in fruits and vegetables by washing processes, samples of lettuce, young Chinese radish, Chinese cabbage, green red pepper, strawberry and grape were artificially contaminated with malathion and washed according to the household practices. After three times washings with water, the remaining ratios of malathion residues in grape, green red pepper, strawberry, young Chinese radish, lettuce and Chinese cabbage were 9.7%, 25.2%, 28.0%, 29.7%, 38.9% and 57.5%, respectively. After washing with detergent solution followed by two times rinsing with water, the remaining ratios of malathion residues in the same food samples were 1.6%, 8.3%, 15.8%, 24.8%, 27.2% and 45.9%, respectively. The removal efficiency of malathion by detergent washing was significantly higher than the water washings only. The removal ratio of malathion residues was the highest in the first washing and the ratio fell greatly in the following washings. The removal efficiency was not quite different in the temperature range of $5-35^{\circ}C$ of the washing solution, but the efficiency at $100^{\circ}C$ was 2-3 times higher than other temperature ranges.

• The Korean Journal of Pesticide Science
• /
• v.15 no.4
• /
• pp.389-400
• /
• 2011

A high-performance liquid chromatographic (HPLC) method was developed to determine residues of phenothrin and silafluofen, known as synthetic pyrethroids, in agricultural commodities. Insecticide residues were extracted with acetone from representative samples of four crops which comprised rice, apple, pepper and cabbage. The extract was purified serially by liquid-liquid partition and Florisil column chromatography. For rice and pepper samples, acetonitrile/n-hexane partition was additionally adopted to remove nonpolar interferences. Reversed phase HPLC using an octadecylsilyl column was successfully applied to separate two phenothrin isomers and silafluofen from sample co-extractives. Intact parent compounds were sensitively detected by ultraviolet absorption at 226 nm. Recovery experiment at the quantitation limit validated that the proposed method could apparently determine phenothrin and silafluofen residues at 0.02 and 0.01 mg/kg, respectively. Mean recoveries of phenothrin and silafluofen from four crop samples fortified at three levels in triplicate were in the range of 82.4~109.8% and 83.7~109.8%, respectively. Relative standard deviations of the analytical method were all less than 10%, irrespective of crop types and spiking levels. A selected-ion monitoring (SIM) LC/mass spectrometry (MS) with electrospray ionization was provided to confirm the suspected residue of phenothrin, even though no sufficient ionization of silafluofen was obtained. Both phenothrin and silafluofen could be successfully confirmed by gas chromatography/MS SIM with electron impact at 70 eV. The proposed method is sensitive, repeatable and rapid enough to apply to officially routine inspection of agricultural products.

• Applied Biological Chemistry
• /
• v.47 no.1
• /
• pp.113-119
• /
• 2004

Persistence of the triazole fungicides, bitertanol and tebucnazole was investigated after their application at recommended and double rate on greenhouse-grown peppers. The half-life of bitertanol and tebuconazole on peppers at recommended and double rate was $5.2{\sim}6.1$ and $4.6{\sim}5.2$ days, respectively. Half-lives of bitertanol and tebuconazole on pepper leaves $(16.8{\sim}22.5\;days)$ was longer than those in the peppers. Residual concentration of bitertanol and tebuconazole on pepper leaves 24 days after application were 10.1 and 17.5 mg/kg, respectively, and these levels were higher than MRL which had been established at 3.0 and 5.0 mg/kg in Korea. Pattern of dissipation was well fitted to the first-order kinetics. In household washing experiment with surfactant, dislodgeable portions on pepper leaves of bitertanol and tebuconazole were occupied 36% and 48% of the residues found 24 days after application.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.46 no.3
• /
• pp.85-92
• /
• 2004

Biomass is considered to be a major potential fuel and renewable resource for the future. In fact, there is high potential to produce significant amount of energy from biomass around the world. In spite of the potential, there are a few efforts in biomass utilization in this nation. In this study, elemental biomass data was obtained with respect to the amount and calorific values of agricultural residues. Rice straw and husks were not included in the evaluation due to their demand from alternative uses such as livestock feedings, bedding materials, and so forth. Dry basis high calorific values are about 4,500 kcal/kg for all the agricultural residues investigated, similar to literature data. Energy densities or unit area energy value, from pepper and sesame were significant and comparable to those of woody biomass. These elemental data for biomass resources will Provide the background of Planning and development of biomass energy Program, which is getting more feasible along with advances in energy conversion technologies such as micro gas turbines.

• Korean Journal of Soil Science and Fertilizer
• /
• v.46 no.6
• /
• pp.570-574
• /
• 2013

This study was conducted to assess $N_2O$ emissions in agricultural soils of Korea under the 1996 IPCC (Intergovernmental Panel on Climate Change) methodology. $N_2O$ emissions in agricultural soils were calculated the sum of direct emission and indirect emission by the N sources and emissions by field burning of crop residues. $N_2O$ emission was highest in animal manure as 1,547 $CO_2$-eq Gg. Indirect emissions by atmospheric deposition and leaching and runoff were 1,463 and 1,753 $CO_2$-eq Gg, respectively. $N_2O$ emission by field burning of crop residues was highest in pepper due to the residue/crop ratio and field burning ratio.