• Korean Journal of Soil Science and Fertilizer
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• v.43 no.1
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• pp.25-35
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• 2010

The periodic application effects of two different herbicides on soil physical properties were observed in a slightly hilly orchard of pear tree located on the southestern flank of the Palbong Mountain in Gongju Chungnam : (1) bare surface vegetation; (2) glyphosate-treated plot; (3) paraquat-treated plot. The slope of experimental plots ranged from 5.5%to 10.2%at an altitude of 125 mand 896 $m^2$ ($28m{\times}32m$) in area. The total respective rainfall events were 47, 52, 52 times during experimental period from 2006 to 2008, while approximately 65 percent of daily rainfall intensity from2006 to 2008 was less than 20 mm a day. The organic matter contents on the surface 15 cm soil ranging from1.23%to 1.84%in 2006 were changed into from1.35 %to 2.28%in 2008 in the order of control > glyphosate > paraquat > bare plot in 2008, indicating that the herbicide treatment influenced the accumulation organic matter in soil. The changes in soil particle contents showed that the loss of soil particles in top 5 cm soil depth was greater in a bare soil than in other treatments such as control, glyphosate, and paraquat-treated plot. The net changes in the bulk densities showed that there were little variations between May of 2006 and Nov. of 2008 even though there were some losses of the soil particles. The soil strength of the glyphosate-treated bare plots was much greater than those of other plots such as control, glyphosate, and paraquat plots. However the soil strengths in control plots were lower than those in the plots of glyphosate and paraquat treated ones.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.4
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• pp.287-292
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• 1981

The field studies were carried out in paddy field over a four year period in order to find out the effects of butachlor, nitrofen, oxadiazon or CG 102, benthiocarb-S, and bentazon applied successively to the same paddy field for four years on weed succession and rice yields under different fertilized conditions including compost, chemical fertilizer and straw application. Total dry weight of weeds was steadily increased yearly over 4 year period regardless of fertilized conditions, and significantly higher increase of weed dry weight was observed on non-fertilized and compost plots. The most dominant weed species was Scirpus hotarui, and Potamogeton distinctus, Eleocharis kuroguwai and Cyperus serotinus were predominated on compost plot, E. kuroguwai and E. aclularis on non-fertilized plot, E. kuroguwai, C. serotinus, and Monochoria vaginalis on chemical fertifizer plot, and C. serotinus on straw plot. When the same herbicides were used continuously on the same plots, weed control effect was decreased and thus weed population was greatly increased particularly on butachlor and nitrofen treated plots. P. distinctus, E. kuroguwai, and C. serotinus were predominated on butachlor treated plot, P. distinctus and C. serotinus on nitrofen treated plot, C. serotinus on benthiocarb-S treated plot, C. serotinus and P. distinctus on oxadiazon or CG 102 treated plot and P. distinctus on bentazon treated plot. Annual weeds were slightly increased by repeated annual application of oxadiazon or CG 102 and benthiocarb-S, whereas perennial weeds were predominated by successive application of butachlor, nitrofen. and bentazon for 4 years. Yield reduction of rice became prominent by successive application of same herbicides. particularly butachlor and nitrafen. This results suggested that successive annual application of same herbicides should be limited and herbicide combination or herbicide rotation should be applied to control the remaining weed species.

• The Korean Journal of Pesticide Science
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• v.10 no.4
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• pp.351-358
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• 2006

This study was conducted to evaluate herbicidal properties of picolinafen in terms of crop safety, weed control spectrum, application window, residual efficacy and resistant weed control. Herbicidal phytotoxicity of picolinafen to wheat and barley was greatest when applied at 0 days after sowing (DAS), but decreased significantly as plant growth advanced. Picolinafen showed greater activity against broadleaved weeds than grass weeds. Picolinafen showed highest activity when it was applied at early post emergence timing (5 to 15 DAS), and showed significantly decreased activity at 20 DAS application. The $LT_{50}$ values (the period from application required for residual control by 50%) was 9.3 and 6.5 days against Digitaria ciliaris and Brasica naus at 60 g ai $ha^{-1}$, respectively. Picolinafen showed similar activities against both triazine resistant and sensitive Amaranthus retroflexus. Collectively, picolinafen appeared to have a good fitness to control resistant broad leaved weeds control by early post emergence application.

• The Korean Journal of Pesticide Science
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• v.9 no.4
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• pp.279-286
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• 2005

The herbicidal activities against pre-emergence barnyard grass (Echinochloa crus-galli) by a series of new 2-(4-(6-chloro-2-benzoxazolyloxy)phenoxy)-N-phenylpopionamide derivatives as substrate molecule were studied using molecular holographic (H) quantitative structure activity relationships (HQSAR) methodology. From the based on the findings, the higher herbicidal active compounds are predicted by the derived HQSAR model. The best HQSAR model (VI-1) was derived from fragment distinction combination of atoms/bonds in fragment size, $7{\sim}10$bin. The herbicidal activities from atomic contribution maps showed that the activity will be able to increased according to the R-substituents variation of the N-phenyl ring and change of 6-chloro-2-benzoxazolyloxy group. Based on the results, the statistical results of the best HQSAR model (VI-1) exhibited the best pedictability and fitness for the herbicidal activities based on the cross-validated value ($q^2=0.646$) and non cross-validated value ($r^2_{ncv.}=0.917$), respectively. From the graphical analyses of atomic contribution maps, it was revealed that the lowest herbicidal activitics depends upon the 4-(6-chloro-2-benzoxazolyloxy)phenoxy group ($pred.pI_{50}=-3.20$). Particularly, the R=4-fluoro, X=isobutoxy substituent (P2) of (X)-phenoxy-N-(R)-phenylpropionamide derivative is predicted as the highest active compound ($pred.pI_{50}=9.12$).

• Applied Biological Chemistry
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• v.38 no.6
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• pp.570-576
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• 1995

The new sixteen herbicidal N-2-(1-hydroxy-2-fluoroethyl)-6-substituted(X)-benzenesulfonyl-N'-4,6-dimethoxypyrimidinyl-2-yl urea derivatives(S) were synthesized and thier herbicidal activities$(pI_{50})$ in vivo against rice(Orysa Sativa L.), Barnyard grass(Echninochloa orizicola) and Bulrush(Scirpus juncoides) were measured by the pot test under paddy conditions. The structure activity relationship(SAR) were studied using the physicochemical parameters of ortho-substituents(X) and hydrolysis rate constant(logk) and herbicidal activities by the multiple regression technique. The SAR suggested that the herbicidal activities were more dependant on the hydrolysis rate constant(logk>0) than the steric constants $(Es, small width($B_4$) and length($L_1$). Among them, halogens(2 & 5), methyl(15) and non(H) substituent(1) showed higher herbicidal activity for weeds which was not tolerent to rise and weeds. The herbicidal activity was increased and the persistency in aqueous solution was decreased by electron donating(${\sigma}0<0$) groups as ortho-substituent(X). From the relationship equation between herbicidal activity and hydrolysis rate constant, it was assumed that the both reactions would be proceeds with similar process. And the conditions on the ortho substituents to show higher herbicidal activity and the persistency in aqueous solution were also discussed.

• The Korean Journal of Pesticide Science
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• v.6 no.4
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• pp.320-323
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• 2002

New and fast degradable sulfonylurea derivaties possessing N-methylureido group were synthesized and their herbicidal effects were tested under the upland in greenhouse. N-methylureido benzenesulfonylureas showed better herbicidal activity against grass weeds than broad leaf weeds under post emergence.

• The Korean Journal of Pesticide Science
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• v.4 no.2
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• pp.72-75
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• 2000

3,4-Dimethyl-N-[4-chloro-2-fluoro-5-{(pyrazolylmethyl)oxy}phenyl]maleimides or 3,4,5,6-tetrahydro-N-[4-chloro-2-fluoro-5-{(pylazolylmethyl)oxy} phenyl]phthalimides were prepared and evaluated their herbicidal activities under paddy conditions. Those compounds which have N-methyl-5-pyrazolylmethyloxy moiety showed good tolerance in transplanted rice and strong herbicidal activities on barnyardgrass below 60 g/ha of dose.

• Korean Journal of Plant Resources
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• v.9 no.1
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• pp.47-54
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• 1996

To search herbicidal compounds in Pulsatilla koreana Nakai, methanol extract of P. koreana roots was purified by sequences of XAD-7 column chromatography, silica gel adsorption column chromatography, silica gel flash column chromatography, preparative layer chromatography and preparative high performance liquid chromatography(Prep, HPLC).The final Prep. HPLC gave two herbicidally-active fractions. These fractions treatment at 100ppm inhibited the root length of Echinochloa crus-galli seedlings by 48% and 60% as compared with the control, respectively. Components in the two active fractions were analyzed by GC-MS Spectrometry. These compounds, which were isolated from P. koreana roots, were identified as several fatty esters, hydrocarbons, squalene, evidonol, and a diazepin analogue.

• Applied Biological Chemistry
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• v.21 no.3
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• pp.185-192
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• 1978

Three herbicides including nitrofen, alachlor and butachlor f?ere applied to farm soils of oil-bearing crops rape, soybean and paddy rice and their residual levels in the soil and seeds were determined by ECD-attached gas chromatograph without hydrolysis. Applied herbicides were decreased abruptly 2 weeks after application and slowly thereafter, reaching below 10% level while the extent of disappearance varied depending on the herbicides, crops and soil conditions. The herbicides were not detected at all in the seeds of tested crops within the detection limit of the analytical methods employed.

• Korean Journal of Organic Agriculture
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• v.10 no.4
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• pp.1-7
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• 2002

CODEX의 유기농업기준에 대하여 기본적으로는 공감하고 있으나, 아시아적 기후의 특성과 농가당 소유면적이 유럽이나 미주$\cdot$오세아니아 지역에 비하여 상대적으로 너무 협소한 점을 감안하여 아시아의 유기벼 재배농가들에게 과중한 부담을 주지 않을 수 있는 선에서의 유연성을 부여해야 할 것이다. 윤작이나 휴경의 경우, 지역에 따라 벼-딸기 등의 과채류-벼-토마토 등 과채류-벼 행태나, 병-보리 또는 호밀 등의 사료 또는 녹비작물-벼-자운영 등의 사료 또는 녹비작물-벼 행태의 윤작 또는 녹비작물 재배형태의 윤작 또한 유기재배로 인정해야 할 것이다. 완충지배 역시, 일정거리 보다는 경계선상에 주작물보다 상당히 키가 큰 다른 식용이나 녹비용 작물을 재배하면서 이웃 관행농장으로부터의 영농화학물질의 비산을 막아줄 수 있는 조처만으로도 유기재배 인증획득이 가능토록 해야 할 것이다. 제체작업 또한 오리를 이용할 경우, 기본적인 제초효과는 물론 해충포식이 이루어지며, 배설물에 의한 자연적인 시비가 원활히 이루어지게 볏대를 튼튼하게 자극시켜주며, 고랑사이의 공기유통 촉진과 흙탕물에 의한 잡초 발아억제 효과 등 다양한 부대효과를 올리 수 있게 된다. 왕우렁이 제초법 또한 논의 건조와 백로 등 조류의 접근만 차단해 주면 완벽한 제초가 이루어지고 있으며, 불시 경운에 의한 제초법도 유기농업 실천에 크게 기여할 수 있는 최선의 방안으로 활용되고 있는 중이다.