• Korean Journal of Organic Agriculture
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• v.15 no.2
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• pp.207-218
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• 2007

Coming with the well-being era, consumer's demand for safe agricultural products is increasing. So, it is urgent to develop an environment-friendly rice production system. Accordingly, this study was conducted to develop an environment-friendly rice production system by using Amo known as EM(effective microorganisms) and also known as being effective in environment-friendly rice production with several other environment-friendly agricultural materials. The highest number of tillers per hill was obtained from level 2 of EM treatment (48.8 tillers per hill), while the lowest was obtained from the control plot (41.0 tillers per hill). Leaf area per hill at heading stage was the highest in level 3 of EM treatment $(3228.5cm^2)$, while control was the lowest leaf area $(2264.7cm^2)$, which is 70.2% compared to the level 3 of EM treatment. The highest effective tillers was obtained from the control (63.7%), while the lowest effective tillers was obtained from the level 3 of EM treatment (55.4%), which were treated with higher amounts of environment-friendly agricultural materials. Level 3 of EM treatment showed the highest number of panicles per hill (20.9), while the control showed the lowest number of panicles per hill (19.3). In the spikelets per panicle, level 2 of EM treatment showed the highest number of spikelets (85.2), while the control showed the lowest number of spikelets (81.9) and there was a statistically significant difference among the three levels and control. The highest grain filling ratio was obtained from the control (85.0%), while level 3 of EM treatment was the lowest grain filling ratio and there were no great difference between treatment levels. Regarding the 1000 grain weight, the control showed the highest 1000 grain weight (21.7g), which is heavier by about 1g compared to treatment levels. Level 2 of EM treatment showed the highest rough rice yield per 10a, while level 3 of EM treatment was the lowest and they also showed a statistically significant difference among treatment levels.

• Korean Journal of Agricultural Science
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• v.35 no.1
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• pp.69-83
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• 2008

The self-supply rate of Korea in 2006 was approximately 27.3 % by importing 13.99Mt for 19.79Mt of demanded amount. Among the imported crops, wheat, corn, and soybean consumed 95 % for the total imported amount, and wheat, corn, and soybean were 3.5Mt(Table use : 0.22Mt; Feed stuff : 0.13Mt), 8.7Mt(Table use : 0.19Mt; Feed stuff : 0.68Mt), and 1.2Mt (Table use : 0.03Mt; Feed stuff : 0.09Mt), respectively. On the other hand, our government has prepared the strategies for a great fear of food according to sharp price rise of the international crops by maintaining the self-supply rate of 5 % excluding 5.23Mt of rice in Korea. Also concern for recycled energy known as future energy for era of high oil price and global warming due to green house gas is rapidly growing. Therefore, our country which has relied on import of the whole oil needed in Korea and has to keep Kyoto Agent to request reduction of green house gas fully support research and practical use for agricultural products as resource of alternate energy. At first, we have to develop the mass production technology in order to secure a program of self-supply of food for bioenergy production utilizing agricultural product in Korea. But we assume that this matter is difficult to achieve under the current agriculture system that more emphasizes the environment conservation such as environmentally-friendly agriculture than production of food.

• Korean Journal of Organic Agriculture
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• v.19 no.spc
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• pp.251-254
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• 2011

Botrytis cinerea infects stems and leaves of greenhouse tomatoes and can cause serious economic losses. This study was conducted to develop environment-friendly control method against tomato gray mold. Antagonistic microorganisms (bacteria) were screened for control activity against Botrytis cinerea, both in vitro and in vivo, using stem sections. One hundred bacterial strains were isolated from the rhizospheric soil of various plants including tomato. These strains were screened for growth inhibition of Botrytis cinerea on agar plate by the dual culture and thirty strains showing strongly inhibitory effect against the pathogen were selected first. Among thirty strains, JB 5-12, JB 22-2, JB 22-3, U 4-8 and U46-6 reduced significantly disease incidence, when applied simultaneously with the pathogen. These results suggested that five antagonistic bacteria strains selected have the potential to control tomato gray mold in organic farming.

• Korean Journal of Environmental Agriculture
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• v.40 no.4
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• pp.260-269
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• 2021

BACKGROUND: Diquat dibromide is a fast-acting nonselective herbicide and plant growth regulator. In this study, in order to understand the possibility of unintentional pesticide contamination in the following crops, the phytotoxicity and transition of diquat dibromide residue in soil into the following crops such as pepper, radish, lettuce and corn have been assessed through phytotoxicity trial and residual evaluation in the unintentional contamination of the higher residual diquat dibromide. METHODS AND RESULTS: The pepper, radish, lettuce and corn were cultivated in the sandy soil and loam soil where the 35 mg/kg and 90 mg/kg diquat dibromide were applied, respectively. Mild growth inhibition symptoms were observed in radish, lettuce and corn crops at the 90 mg/kg- diquat dibromide treatment on the 30 day of cultivation. Diquat dibromide was analyzed using liquid chromatography QTRAP (LC-MS/MS). The recovery rates of diquat dibromide from soil and crop were determined within range from 89.1 to 116.4% with relative standard deviation less than 14.7%. Diquat dibromide residues in soil were found to be 23.90-30.22 and 69.59-82.57 mg/kg from the 35 mg/kg and 90 mg/kg of diquat dibromide-treated soil, respectively after 30 days of crop cultivation. This result implicates that diquat dibromide did not convert to metabolites and remained mostly in the soil, even though it was partially decomposed during crop cultivation. In addition, the diquat dibromide in pepper and radish that were grown for 47 days, and lettuce and corn that were cultivated for 30 days were detected to be 0.01 mg/kg or less in the sandy loam and loam soil where the 90 mg/kg diquat dibromide was applied. CONCLUSION(S): Diquat dibromide did not cause severe phytotoxicity in the following crops as well as it did not uptake and distribute to the following crops, even though it was considered to be residual in the soil.

• Korean journal of applied entomology
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• v.46 no.2
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• pp.261-267
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• 2007

Bioassay of mosquito, Culex pipiens molestus, larva was investigated by several environment-friendly insecticides. These insecticides were Novaluron as chitin synthesis inhibitor, Metho-xyfenozide as ecdysone agonist, Pyriproxyfen as juvenile hormone mimic, and Spiromesifen as lipid biosynthesis inhibitor. The 50% lethal concentration $(LC_{50})$ of these insecticides were 0.00039, 0.07193, 0.65006 and 0.04839 ppm, respectively. Novaluron has lower concentration than any other insecticide. To determine the treatment time against larval stages, insecticides were applied to different larval stages of C. pipiens molestus. Mortality ratios of mosquito larva treated with Novaluron were 100.0, 84.5, 71.0 and 48.5% on 2, 4, 7 and 10 days after hatching from eggs, respectively. Otherwise, with the other insecticides, mortality ratios were under 80% with 2 days old larva. When exposure periods were tested to 3 or 4 days old larva against 4 insecticides, at least 3 hours were needed to 100% control effect against Novaluron, and over 12 hours with other insecticides.

• Korean Journal of Environmental Agriculture
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• v.30 no.1
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• pp.76-81
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• 2011

BACKGROUND: Acorus gramineus is of medicinal plants that exhibit variable biological activities for human health and against insect pests. The extracts of A. gramineus was examined in an attempt to develop a natural repellent against human disease-mediating Culex pipiens. METHODS AND RESULTS: The roots of A. gramineus dried under dark conditions were homogenized and extracted with ethanol. The extracts were subjected to repellent activity assays against C. pipiens in a hand-made acrylamide box with three accessible rooms. Significantly low number of mosquitos was found in the room previously fumigated with the extracts at 50 mg/L on the filter paper, exhibiting less than 20% of mosquitos tested. More than 50% of mosquitos tested was found in the room without the extracts, but less than 30% was found in the room that released mosquitos. GC/MS analysis detected ${\beta}$-asarone as a main component of the extracts. The commercial asarones (${\alpha}$ and ${\beta}$) showed a repellent activity at 50 mg/L on the filter paper similar to the extracts. CONCLUSION(S): A. gramineus has potential for use as a mosquito repellent since ${\beta}$-asarone, a main component of the plant, exhibited a strong repellent activity against C. pipiens.

• Korean Journal of Environmental Agriculture
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• v.30 no.2
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• pp.173-178
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• 2011

BACKGROUND: Starfish is one of major sea invertebrates that have become a serious economic threat to aquacultural farms in Korea. Much effort has sacrificed to reduce the economic losses of the farms by predatory starfish, including developing and searching biological resources for medicinal and agricultural purposes. In the present study, we investigated aphicidal activity of the extracts from the starfish Asterina pectinifera against green peach aphid. METHODS AND RESULTS: Fresh starfishes were cut into small pieces, homogenized and soaked in methanol. The methanol extracts were centrifuged and the resulting supernatant was subjected to aphicidal activity assays and a series of silica gel column chromatography. More than 70% mortality of aphids were observed by the extracts at a concentration of 1,000 mg/L, exhibiting dose-dependent mortality. TOF-MS analyses detected polyhydroxysteroid as a main aphicidal compound from the starfish extracts. Transmission electronic microscopy could demonstrate that the extracts with polyhydroxysteroid caused aphids death by affecting their epicuticular membrane. CONCLUSION(s): This is the first report of aphicidal activity of the starfish Asterina pectinifera extracts against green peach aphid. Starfish biological resources may be used as a potential candidate for developing a new type natural insecticide.

• Korean Journal of Environmental Agriculture
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• v.41 no.1
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• pp.55-64
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• 2022

BACKGROUND: This study was conducted to evaluate the residual characteristics and safety assessment of αcypermethrin and deltamethrin in minor crops, chives and spring onion cultivated in greenhouse. METHODS AND RESULTS: The insecticides α-cypermethrin 2% EC and deltamethrin 1% EC used in the experiment were diluted 1,000 times and then sprayed on chives and spring onion twice with 1-week intervals at 0, 7, 14, and 21 days before harvest. The residual insecticides were extracted from the minor crops using QuEchERS method and analyzed by GC-MS/MS. The average initial residues of α-cypermethrin and deltamethrin in chives after 21 days decreased from 2.74 to 0.82 mg/kg and 1.12 to 0.16 mg/kg, respectively. Similarly, in spring onion the residues after the same periods decreased from 0.26 to <0.01 mg/kg for α-cypermethrin and from 0.07 to <0.01 mg/kg for deltamethrin. CONCLUSION(S): The PHIs (pre-harvest intervals) for α-cypermethrin and deltamethrin in chives are recommended as 14 days before harvest with twice applications of the pesticides, whereas for α-cypermethrin in spring onion PHI of 7 days before harvest is recommended with 3 times of applications and PHI of 21 days for deltamethrin. The theoretical maximum daily intakes of cypermethrin and deltamethrin were 68.8% and 64.2%, respectively, indicating that residues of both compounds did not pose considerable health risks to consumers.

• Journal of Practical Agriculture & Fisheries Research
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• v.12 no.1
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• pp.3-10
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• 2010

In order to promote the growth of the trees, it is the most important to fertilize efficiently. The organic nutrient "Green-one" which list public notification number 08-organic-3-112" was registered in Rural Development Administration. The "Green-one" is the environment friendly organic nutrient with new concept which is used in planting and maintenance of the trees. The "Green-one" makes the tree grow actively. Also it has a function of the anti germ and sustainable fertilizer effect. In conclusion, "Green-one" promoted the growth of P. thunbergii excellently. Expecially the growth of the root increased. The concentration of "Green-one" dilution was more better 100 times than 300 times in trees grow. This research can apply with the test of fertilizer efficiency in landscape trees.

• Korean Journal of Soil Science and Fertilizer
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• v.50 no.4
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• pp.318-324
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• 2017

Lime bordeaux mixture (LBM) and lime sulfur mixture (LSM) are representative environmental friendly organic materials for prevention of insect pests in South Korea. Recently, those have been widely used as an alternative for chemical pesticides in eco-friendly farms. However, South Korea has not established even recommendation of LBM and LSM considering the stability of heavy metals in soil. The aim of this study was to evaluate the accumulation of hazardous heavy metals in soil and plant with long-term application of LBM and LSM. Firstly, we investigated the amount of LBM and LSM used per year in several eco-friendly farms to determine a standard application rate of both materials. The pepper plant was grown on the pot in greenhouse for 14 weeks. Both materials were applied at 0, 1, 3, and 9 times of standard application rates (2.56 and $1.28L\;ha^{-1}$ of LBM and LSM per year, respectively). Dry matter yield of pepper and heavy metals (As, Cd, Cu, Hg, Ni, Pb, and Zn) concentration in soil and pepper plant were measured after 14 weeks. Yield of pepper plant did not significantly chang with up to application rate of 1 times, thereafter it markedly decreased with more than 3 times. With increasing LBM and LSM application, the concentration of Cu and Zn in soil significantly increased. Especially, Zn concentration in pepper significantly increased with increasing application rates of both materials. This might resulted in significant decrease in dry matter yield of pepper. The concentrations of those heavy metals in soil did not exceed safety levels ($150mg\;kg^{-1}$ for Cu and $300mg\;kg^{-1}$ for Zn) established by the Korean Soil Environmental Conservation Act as well as concentration of heavy metals in pepper plant by Korean Ministry of Food and Drug Safety. However, particular attention should be paid for heavy metal safety and crop productivity when using LBM and LSM in the organic farm.