• Korean Journal of Environmental Agriculture
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• v.14 no.1
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• pp.45-54
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• 1995

esters of the acid analytes were synthesized using $H_2SO_4$ as the catalyst. Efficiency of derivatization and instrumental molecular-response were compared with herbicides methylated with $BF_3-methanol$(14% W/V), $H_2SO_4-methanol$(33% V/V), and diazomethane. The molecular integrity of TFE-2,4-D, TFE-dicamba, and TFE-mecoprop, in the mixture, was confirmed by the GC/MSD method. The TFE-Esterification efficiency was maximized by adjusting the volume of $H_2SO_4$ the reaction time, and temperature. Optimal efficiency for the herbicide mixture was obtained by adding 1 ml of $H_2SO_4$ and 1 ml of TFE to the dried sample and allowing the reaction to proceed at $22^{\circ}C$ for 8 hr or using 0.5 ml $H_2SO_4$ and 1 ml of TFE at $60^{\circ}C$. For 120 min increasing the temperature and decreasing the reaction time were required for maximum esterification efficiency. The sensitivity of the GC/ECD to the TFE esters was about $2{\sim}20$ times greater than that to the methyl ester derivatives. The herbicides were extracted and esterified to TFE derivatives simultaneously from soil leachates previously spiked with the analytes. Herbicide recovery, peak resolution, and detector sensitivity were excellent without using column cleanup procedures.

• Journal of Ecology and Environment
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• v.36 no.1
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• pp.39-47
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• 2013

The expression of transgenic traits in genetically modified crops is sometimes associated with decreases in crop performance or fitness. These decreases in performance or fitness of transgenic plants in unfavourable conditions may provide valuable information about the ecological consequences of transgene escape. In a glasshouse trial, we tested the cost associated with resistance to herbicides by comparing the growth, yield, and competitive ability of transgenic rice with its parental non-transgenic line. This new line was developed for constitutive overexpression of protoporphyrinogen oxidase (PPO) to increase resistance to herbicides. We evaluated nine agronomic traits of transgenic and non-transgenic rice grown in a replacement series design over four densities. Competitive ability was also assessed between transgenic and non-transgenic plants by analyzing their relative yields based on biomass and seed weight data. Our results indicated that non-transgenic plants showed greater performance than did the transgenic plants when those genotypes were grown in mixtures. The non-transgenic rice plants exhibited superior competitive ability at certain combinations of planting densities and genotype proportions. These results suggest that PPO-herbicide resistance incurs some costs in plant performance and competitive ability.

• Applied Biological Chemistry
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• v.40 no.4
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• pp.277-282
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• 1997

Acetolactate synthase (ALS) was partially purified from Escherichia coli MF2000/pTATX containing Arabidopsis thaliana ALS gene. The partially purified ALS was examined for its sensitivity toward various modifying reagents such as iodoacetic acid, iodoacetamide, N-ethylmaleimide (NEM), 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB), p-chloromercuribenzoic acid (PCMB), and phenylglyoxal. It was found that PCMB inhibited the enzyme activity most strongly followed by DTNB and NEM. Since iodoacetic acid did not compete with substrate pyruvate, it appeared that cysteine is not involved in the substrate binding site. On the other hand, the substrate protected the enzyme partly from inactivation by phenylglyoxal, which might indicate interaction of arginine residue with the substrate. The partially purified enzyme was inhibited by end products, valine and isoleucine, but not by leucine. However, the ALS modified with PCMB led to potentiate the feedback inhibition of all end products. Additionally, derivatives of pyrimidyl sulfur benzoate, a candidate for a new herbicide for ALS, were examined for their inhibitory effects.

• The Korean Journal of Pesticide Science
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• v.8 no.3
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• pp.175-183
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• 2004

The characteristics of the experimental compound EK-5439 [3-Chloro-2-[4-chloro-2-fluoro-5-(5-methyl-3-phenyl-4,5-dihydroisoxazol-5-yl-methoxy)-phenyl]-4,5,6,7-tetrahydro-2H-indazole] was investigated to characterize as a new herbicide to use in rice field. The selectivity between rice and barnyardgrass was very good when treated from 0 to 4 days after seeding under soil application. In the overflowing experiment, herbicidal efficacy of EK-5439 was stabilized 12 hrs after application. Vertical migrations in submerged paddy soil of EK-5439 and oxadiazon were equally observed below a soil depth of 1 cm under 5 cm/day leaching condition. Half-lives for herbicidal efficacy of EK-5439 and oxadiazon were 6.1, and 9.6 days, respectively, under submerged paddy condition. EK-5439 showed rapid adsorption to the soil clay, such as bentonite.

• Korean Journal of Weed Science
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• v.7 no.1
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• pp.74-77
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• 1987

This study was undertaken to elucidate the behavior of herbicide bensulfuron methyl [ methyl 2-[[[[[(4, 6-dimethoxy pryrimidine-2yl) amino] carbonyl] amino] sulfonyl] methyl] benzoate] in soils under flooded conditions using the test plant Monochoria vaginalis Pres 1. Besulfuron methyl moved to 3cm depth in clay loam soil and 4 cm depth in sandy loam soil. Herbicide-treated layer was found 0 to 2 cm profile in the former and 0 to 3 cm profile the latter. The half life (GR50) was 87 days in clay loam soil and 78 days in sandy clay loam soil. The period of inactivation lasted for 110 days in clay loam and 100 days in sandy clay loam soil.

• Korean Journal of Weed Science
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• v.17 no.3
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• pp.256-261
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• 1997

Effect of a new postemergence herbicide carfentrazone-ethyl on controlling weeds in pear orchards was examined and compared with that of glyphosate and glufosinate. Herbicides tested were applied in mid June when weeds had reached at an average height of 15 to 20cm. The experimented orchards were infested mainly by dicots of Artemisia princeps, Chenopodium album, Polygonum hydropiper, Erigeron canadensis, Commelina cummunis, Calystegia japonica, and Amaranthus ascenders, and monocots of Echinochlor crus-galli, Digitaria sangunalis, Setaria viridis, and several sedges, Carfentrazone-ethyl alone effectively controlled dicot weeds in the orchards, but not monocot weeds. Especially, sedges were not adequately controlled by carfentrazone-ethyl alone at any application rates examined. Glyphosate or glufosinate was more effective to control monocot weeds than carfentrazone-ethyl, whereas carfentrazone-ethyl exhibited higher effect on dicot weeds than glyphosate or glufosinate. Carfentrazone-ethyl mixed with glyphosate of the half recommended rate exhibited a higher degree of weed control, especially of E. crus-galli, as compared to the herbicide mixture of carfentrazone-ethyl with glufosinate of the half recommended rate. However, no phytotocixity of the herbicides to pear trees was observed. Our results demonstrate that catfentrazone-ethyl is useful to reduce the application rates and to accelerate the weed controlling effect of glyphosate or glufosinate. Thus, carfentrazone-ethyl in combination with glyphosate or glufosinate can successfully be used to control the most important weeds in orchards.

• Weed & Turfgrass Science
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• v.7 no.3
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• pp.219-229
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• 2018

We isolated Streptomyces scopuliridis KR-001 that produced herbicidal active metabolite(s) against several grass and broad leaf weeds. In this study, potential as natural herbicide of mutant N-29 broth filtrate of S. scopuliridis KR-001 was investigated to Ambrosia artemisiifilia in a greenhouse and field condition. The broth filtrate of mutant N-29 by foliar application showed a strong herbicidal activity to A. artemisiifilia with leaf stage in a greenhouse condition. Also, field trial of foliar application within treatment range had effectively controlled with early and middle stage of A. artemisiifilia at the natural habitats. Phytotoxic symptoms of mutant N-29 broth filtrate by foliar application were wilting and discoloration, and burn-down of leaves and finally plant death. These results suggest that mutant N-29 broth filtrate is considered possible as a natural herbicide for controlling environmentally friend to invasive alien plant such as A. artemisiifilia and may provide a new lead molecule for a more efficient herbicide.

• Weed & Turfgrass Science
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• v.5 no.3
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• pp.111-125
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• 2016

Cordgrass (Spartina spp.) is recognized as a highly invasive plant in estuaries throughout the world because of remarkable versatility and resiliency, significant reproduction, strong adaptability, rapid spreading, and vigorous growth. In this review, therefore, to provide insights on the effective management practices, the previous research works were summarized and discussed. Spartina spp. is a perennial halophyte, warm-season (C4) grass that reproduces both sexually through seeds and asexually by rhizomes. Management strategies for cordgrass have included various physical, biological, and chemical controls. Herbicides are usually the most cost-effective means of control. Currently, glyphosate, imazapyr, fluazifop and haloxyfop have been practically used. To improve the control efficacy, a combination of two more than methods (example, mowing-spraying) is needed to be applied consistently every year for at least 3 to 4 years and to be sprayed with enough dry time (>4-6 hr) at an early growth stage (before flowering). Consistently repeated application of same herbicide have to be avoided to prevent an unexpected emergence of herbicide-resistant lines. On the other hand, Spartina spp. have many positive functions for agricultural and eco-engineering purposes. Thus, we have to give more intensive research for effectively managing advantages and disadvantages of Spartina plantations.

• Korean Journal of Weed Science
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• v.5 no.2
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• pp.175-186
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• 1985

Research situation and recent research activities of the RDA of Korea were reviewed and summarized for rice nurserybed. Sixty five percent of total 784 weed research items were carried out as rice research while only 6 percent was belonged to nurserybed within rice research. The floristic composition based on the degree of dominance significantly affected by herbicide properties, type of nurserybed and seeding itself. Herbicidal phytotoxicity of currently used several herbicides was greatly dependent upon the covering, absorption, germination, and irrigation regimes. The new safening agent "CGA 123 407" (4,6-dichloro-2-phenyl-pyrimidine) permited the safe application of pretilachlor (2-chloro-2',6-diethyl-N-(2-propoxyethyl) acetanilide) as a pre-emergence herbicide without reducing herbicidal efficacy. Several new herbicides, pyrazolate (4-(2,4-dichlorobenzoyl)-1,3-dimethylpyrazol-5-yl-p-toluenesulphonate), SL-49 (1,3-dimethyl-4-(2,4-dichlorobenzoyl)-5-phenacyloxy-pyrazole) MY-93 (S(1-methyl-1-phenethyl)-piperidine-1-carbathioate) and DPX-84 ((methyl 2- ((4,6-dimethoxypyrimidin-2-yl) amino-carbonyl) aminosulfonylmethyl)) benzolate)) performed satisfactorily in terms of safety and herbicidal efficacy for both surface covered and surface pressed nurserybed after herbicide application and thus expected very significant contributions not only for all kind of nurserybeds but also for direct seeding.

• Journal of Microbiology and Biotechnology
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• v.8 no.4
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• pp.347-352
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• 1998

A new strain of Pseudomonas aeruginosa growing in a rice field contaminated with herbicide and effluents of a factory manufacturing explosives was isolated. This isolate showed excellent growth in unusually high concentration of acrylamide (60 mM). It utilized acrylamide as the sole source of carbon and nitrogen for growth. Other amides such as acetamide, butyramide, isobutyramide, and methacrylamide were also utilized for the growth by this isolate. Acrylamide was degraded into acrylic acid and ammonia by the enzyme amidase. More than $65\%$ of added acrylamide (40 mM) was converted into acrylic acid after 40 h of growth of the culture. Amidase activity was inducible, the highest activity being observed with isobutyramide ($12.5{\mu}M$ ammonia/mg protein/min). These results demonstrate that this bacterium can degrade a variety of amides.