• Korean Journal of Weed Science
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• v.15 no.3
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• pp.232-237
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• 1995

Effect of azimsulfuron {1-(4,6-dimethoxypyrimidin-2-yl)-3-[1-methyl-4-(2-methyl-2H-tetrazol-5-yl) pyrazol-5-ylsulfonl]urea} combined with eight annual herbicides on shoot and root growth of rice (Oryza sativa L.) and barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.] was investigated. Annual herbicides used were four thiocarbamates (dimepiperate, molinate, esprocarb, and thiobencarb), two acetanilides (butachlor and pretilachlor), one urea (dymron), and one oxadiazole (oxadiazon) herbicide. Growth inhibition in rice shoot was greater with azimsulfuron mixed with the annual herbicides than with azimsulfuron only. The azimsulfuron mixtures did not bring about decrease in growth inhibition of rice shoot. However, safening effect in root growth of rice was obtained when dimepiperate, molinate and dymron were combined with greater than 10ppm of azimsulfuron. Greater inhibition in shoot and root growth of rice occurred with straight chain hydrocarbon substitute such as esprocarb and thiobencarb than with cyclohydrocarbon substitute such as dimepiperate and molinate. Application of the azimsulfuron mixtures resulted in increase. in growth inhibition of shoot and root growth of barnyardgrass as compared with when azimsulfuron only was applied.

• The Korean Journal of Pesticide Science
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• v.15 no.1
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• pp.48-54
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• 2011

Risk assessments of pesticides detected in six major rivers during peak season were estimated for algae, Daphnia, and fish using hazard quotient (HQ) indexes. The eight pesticides (isoprothiolane, hexaconazole, diazinon, chlorpyrifos, prothiofos, alachlor, butachlor, molinate) were detected within the range of 0.027~12.871 ${\mu}g/L$. Detection frequency of isoprothiolate was estimated to be high at 67.5%, and those of the others varied from 15.0 to 37.5%, Hazard Quotients (HQ) indexes varied by freshwater organisms (algae, Daphnia, and fish). Overall, the ecological risk probability due to exposure of pesticides detected in major rivers did not reveal based on HQ indexes below 1.0. Particularly, butachlor and molinate for algae, chlorpyrifos, diazinon, prothiofos for Daphnia, and chlorpyrifos for fish acted as dominant contributors in increasing the ecological risk in six major rivers. This implied that integrated ecological risk assessment is required using various biological species, reflecting toxicity sensitivity. This study may provide the essential data in establishing the priority for pesticides management in major rivers, Korea.

• The Korean Journal of Pesticide Science
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• v.10 no.3
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• pp.172-182
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• 2006

This study was designed to assess molinate fate in the lysimeter by measuring the total radioactivity in the leachate, evolved $^{14}CO_2$, and $^{14}C$-residues in soil and rice plant. The amounts of applied $^{14}C$ in the leachate from the lysimeter for 20 weeks were 1.05% in 2.31 pore volume (217,465 mL) at the first and 0.34% in the second year, respectively. The amount of $^{14}CO_2$ evolved from the lysimeter accounted for 6.47% and 0.03% of applied $^{14}C$ in the first and second year. The $^{14}C$-activities in the soil layer of the lysimeter were distributed 18.0% (1st) and 13.3%(2nd) in the depth of 0 to 10 cm, 4.3 (1st) and 1.1% (2nd) in the depth of 10 to 20 cm. Most of the applied $^{14}C$ was detected in the top 20 cm soil layer. Total $^{14}C$ in rice plants grown at lysimeter were detected 11.46% of applied $^{14}C$. 11.11% in straw, 0.24% in brown rice grain, 0.08% in chaff and 0.03% in ears were distributed in the first year. Consequently, environmental fate of molinate using lysimeter simulating a paddy rice field were investigated 25.24% in soil, 11.64% in rice plant, 1.05% in leachate, 6.74% in evolved $^{14}CO_2$ and 0.02% in volatilized organic chemicals in the first year.

• Korean Journal of Weed Science
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• v.17 no.1
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• pp.24-30
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• 1997

The influence of nutrients on the phytotoxicity of herbicides (bensulfuron-methyl, pyrazosulfuron-ethyl, imazosulfuron, dimepiperate, and molinate) was investigated in controlled-environment growth chamber with direct-seeded rice (Oryza sativa L. cv. Dongjin). The phytotoxicity of bensulfuron-methyl, pyrazosulfuron-ethyl, and imazosulfuron for rice was greater in nutrient culture than in no-nutrient condition. The root growth of rice applied with these herbicides was more inhibited than the shoot growth. The most severe inhibition was obtained with pyrazosulfuron-ethyl application. The growth inhibition of rice applied by dimepiperate was increased under no-nutrient culture condition. Dimepiperate suppressed more remarkably shoot growth than root. Especially the shoot elongation was much more inhibited than the others. The shoot growth inhibition in rice applied by molinate was severer than the root. The shoot growth was reduced under nutrient culture condition, while the root growth was reduced under no-nutrient culture.

• The Korean Journal of Pesticide Science
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• v.9 no.3
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• pp.205-213
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• 2005

This study was conducted to evaluate the response of the selected aquatic plants to sulfonylurea(SU)-herbicides, which have been used widely in rice-cultivating areas in Korea, and the possibility of using them as bio-indicator species for biodiversity conservation. The aquatic plants identified in Kangwon province where butachlor have been used extensively for many years were much more varied than those in Chonnam where SU-herbicides have been used extensively for many years. The growth responses of Monochoria korsakowii, Marsilea quadrifolia and Salvinia natans to sulfonylurea herbicides such as bensulfuron-methyl(BSM) and pyrazosulfuron-ethyl(PSE), were much more sensitive than those to butachlor and molinate. The $GR_{50}$ values of BSM and PSE for M. korsakowii, M. quadrifolia and S. natans were relatively very low when compared with those of butachlor and molinate. The number of internode and dry weight of M. quadrifolia which was exposed to herbicides runoff from rice fields were seriously affected. The acetolactate synthase(ALS) activities of M. quadrifolia sensitively inhibited by BSM and PSE were, and $I_{50}$(Inhibition 50%) were 5.6 and 2.1 nM, respectively.

• Korean Journal of Weed Science
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• v.15 no.1
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• pp.46-53
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• 1995

The herbicidal activity of thiocarbamate herbicides and its effect on cell division and elongation were determined. The herbicides studied were molinate(S-ethyl-N,N-hexamethylenethiocarbamate), dimepiperate [S-(${\alpha}$,${\alpha}$-di methylbenzyle)piperidine-1-carbothioate], esprocarb [S-benzyl-N-ethyl-N-(1,2-dimethylpropyl) thiocarbamate], and thiobencarb [S-(4-chlorobenzyl)-N, N-diethylthiocarbamate]. The herbicides applied at the rates ranged from $10^{-6}$ to $10^{-5}M$ did not affect germination and post-germination root growth of rice(Oryza sativa L.) and barnyardgrass [Echinochloa crus-galli(L.) P. Beauv.], but inhibited the post-germination shoot growth. There was no inhibition of gibberellin-induced ${\alpha}$-amylase biosynthesis in de-embryonated rice seeds by the herbicides at $10^{-5}M$, but about 50-60% inhibition occurred at $10^{-4}M$. When the herbicides were applied 7 days after seeding, the rates required to 50% growth inhibition of barnyardgrass were 146g, 91g, 96g, and 102g ai/10a for molinate, dimepiperate, esprocarb, and thiobencarb, respectively. No effect of the herbicides on cell division was found at $10^{-4}M$, but about 31 to 47% inhibition as compared with the untreated check was obtained by treatment of the herbicides at $10^{-3}M$. However, about 33 to 38% inhibition of cell elongation occurred at $10^{-5}M$ of the herbicides. They also inhibited IAA-induced cell elongation.

• Korean Journal of Weed Science
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• v.18 no.1
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• pp.28-35
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• 1998

Cyhalofop/bentazon ME and pyribenzoxim EC herbicides were originally developed as foliarapplied herbicides to control weeds at 4-5 leaf stages of barnyard grass 20-25 days after seeding (DAS) in direct-seeding culture but further possible utilization of these two herbicides earlier than 3-4 leaf stages of rice were evaluated for a field where early weed infestations might be severe. The application of cyhalofop/bentazon ME and pyribenzoxim EC at right after rice emergence and the 2-3 leaf stages of rice had an excellent weed control efficacy with above 90% up to 30 DAS without a phytotoxicity of rice plant and the control efficacy of over 80% was maintained until 60 DAS. However, these two herbicides controlled Echinochloa crus-galli very effectively above 97% but Aneilema keisak and Aeschynomene indica were not controlled by cyhalofop/bentazon ME and Cyperus serotinus by pyribenzoxim EC. Therefore, to control those problem weeds, second systematic application of pyribenzoxim EC and pyrazosulfuron/mefenacet G for A. keisak and A. indica, and pyrazosulfuron/molinate G, cyhalofap/ azimsulfuron/molinate G, pyrazosulfuron/mefenacet G and bentazon SL for C. serotinus at 30 DAS was found to be very efficient herbicide systems.

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 1996.12a
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• pp.65-65
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• 1996

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 1996.12a
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• pp.66-66
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• 1996

• The Korean Journal of Pesticide Science
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• v.2 no.1
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• pp.32-39
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• 1998

This study was performed to develop jumbo granules floated and spreaded on the water surface after application, having low production and formulation cost, and safe to environment for paddy herbicides and to establish the formulation recipe. The jumbo granules of azimsulfuron with molinate(0.075+7.5%) was formulated by KCl as water soluble carrier and paraffin oil as solvent to impose the floating and spreading force to granules. That showed 100% of total granules to be floated on and spreaded upto the water surface within 25 minutes after application. Change in carriers, surfactants and pH did not affected to improve the time-course degradation of azimsulfuron in jumbo granules, but salt formation of azimsulfuron added by 1.15M solution of NaOH a little. Addition of N-methyl acrylate and modification of formulation process affected decrease in degradation of azimsulfuron upto 1.2, 2.1, and 7.2% after 2, 6 and 12 weeks under storage at $40{\pm}2^{\circ}C$, respectively, which showed the establishment of formulation recipe of the jumbo granules.