• Weed & Turfgrass Science
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• v.2 no.1
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• pp.38-46
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• 2013

With increasing environmental issues from synthetic chemical herbicides, microbe-originated herbicides could be a fascinating alternative in current agriculture. We isolated Streptomyces strains that produced herbicidal active metabolite(s) against a grass weed Digitaria sanguinalis. According to the result from 16S rDNA sequence comparison with the close strains, the best isolate (Code name MS-80673) was identified as Streptomyces scopuliridis KR-001. The closest type strain was Streptomyces scopuliridis RB72 which was previously reported as a bacteriocin producer. The optimal culture condition of S. scopuliridis KR-001 was $28^{\circ}C$, pH 7.0 and culture period 4 to7 days. Both of soil and foliar application of the crude culture broth concentrate was effective on several troublesome or noxious weed species such as a Sciyos angulatus in a greenhouse and field condition. Phytotoxic symptoms of the culture broth concentrate of S. scopuliridis KR-001 by foliar application were wilting and burndown of leaves, and stems followed by discoloration and finally plant death. In crops such as rice, wheat, barley, hot pepper and tomato, growth inhibition was observed. These results suggest that the new S. scopuliridis KR-001 strain producing herbicidal metabolites may be a new bio-herbicide candidate and/or may provide a new lead molecule for a more efficient herbicide.

• Korean Journal of Weed Science
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• v.3 no.1
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• pp.69-74
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• 1983

The behaviour of mixtures of herbicides was determined to obtain the basic informations about effective herbicide use, enhancing herbicidal efficacy and reducing the chemical cost. Fourteen herbicides with 91 mixed combinations were evaluated by Limpel et al method at the Echinochloa crus galli Beauv-Monochuria vaginalis Presl.-Scirpus hotarui Ohwi (importance values of these weeds were 63%, 16% and 10%, respectively) community type. Thirty eight mixed combinations showed the antagonistic response. Among these 14 mixed combinations including chlormethoxynil + naproanilide mixture were greater than 11% in antagonistic effect. On the other hand, 40 mixed combinations including chlormethoxynil + SW751 mixture showed additive response (${\pm}2%$). For synergistic response, 13 mixed combinations were belonged to this group. Particularly, 3 mixed combinations, chlormethoxynil + butachlor, chlormethoxynil + bifenox and nitrofen + ACN/MCPB/nitrofen mixtures were greater than 11% in synergistic effects. The mixture of thiobencarb + oxyfluorfen was analyzed by isobole technique. This mixture showed the synergistic response and the interaction index was approximately 2. The most optimum mixtur for inducing 90%n weed suppression was 0.012 kg ai/ha for oxyfluorfen and 0.45 kg ai/ha for thiobencarb.

• The Korean Journal of Pesticide Science
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• v.9 no.3
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• pp.250-261
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• 2005

This study was conducted to investigate the herbicidal response and effective control strategy of sulfonylurea(SU)-resistant Scirpus juncoides Roxb. occurred in the paddy fields of Korea. A biotype of Scirpus juncoides Roxb. resistant to SU was identified in the paddy fields treated with SU herbicide-based mixtures for seven consecutive years. The apparent SU resistance observed in Scirpus juncoides Roxb. was completely confirmed in greenhouse tests. The susceptible biotype was almost controlled at the recommended dose of all the tested, but the resistant biotype was survived 20 to 30% even at 10 times higher dose of each the recommended dose of SU herbicides. The $GR_{50}$ values of 4 SU herbicides for the resistant biotype were 53 to 88 times higher than those for the susceptible biotype. The acetolactate synthase(ALS) isolated from the resistant biotype against bensulfuron-methyl and pyrazosulfuron-ethyl was less sensitive than that of the susceptible biotype. The $I_{50}$ values of the resistant biotype against bensulfuron-methyl and pyrazosulfuron-ethyl were 498 and 126 times higher than those for the susceptible biotype. A rapid diagnosis for identifying resistance of Scirpus juncoides Roxb. was possible within at least 3 days after SU herbicides. Three herbicides having different mode of action from SU herbicide, carfentrazone-ethyl, pyrazolate and simetryne exhibited excellent controlling effects on the resistant biotype of Scirpus juncoides Roxb. till 3.5 leaf stage. Among the SU-based herbicides, pyriminobac-methyl+pyrazosulfuroil-ethyl+carfentrazone-ethyl GR and azimsulfuron+carfentrazone-ethyl+pyriminobac-methyl GR were very effective to control resistant biotype of Scirpus juncoides Roxb. without rice injury. The resistant biotype which were not controlled with SU herbicise-based herbicides survived from the fields were effectively controlled by bentazone SL.

• Korean Journal of Weed Science
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• v.31 no.3
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• pp.294-307
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• 2011

This experiment carried out to confirm characteristics of macrogranule (GG) for herbicidal efficacy by using remote-controlled aerial application (RCAA) to control annual and perennial weeds in rice paddy field, application methods, and application times of formulation types. Particle of 500 g GG having average diameter of 2.5~3 mm was over 85 percent, the bulk density of the particle was $0.2\sim0.4g\;mL^{-1}$ and the particle was water floating granule. Active ingredients and external form of halosulfuronmethyl+mefenacet GG remained stable under condition of storage stability test. The disintegration time of the GG was faster as the water temperature was increased. But disintegration time was not affected by pH on the water conditions. By using hand, spoon and power applicator, drift distances of GG were 4~5m, 7 m and 10~12 m, respectively. GG showed good herbicidal efficacy and plant safety in all of the application methods such as, using hand, spoon, power applicator and RCAA. Application times of GG, GR, SC and TB by hand in $4,000m^2$ were 38 min. 4 sec, 42 min. 20 sec, 38 min. 10 sec and 21 min. 4 sec, respectively, but application time of GG by using RCAA was 1 min 32 sec. According to appearance and characteristics of formulation types, suspension concentrate (SC) and GG were possible formulation types for RCAA.

• Korean Journal of Environmental Agriculture
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• v.38 no.4
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• pp.321-331
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• 2019

BACKGROUND: Pinoxaden is the phenylpyrazoline herbicide developed by Syngenta Crop Protection, Inc. and marketed on 2006. The maximum residue levels for wheat and barley were set by import tolerance. Thus, Ministry of Food and Drug Safety (MFDS) official analytical method determining Pinoxaden residue was necessary in various food matrixes. Satisfaction of international guideline of CODEX (Codex Alimentarius Commission CAC/GL 40) and National Institute of Food and Drug Safety Evaluation-MFDS (2017) are additional pre-requirements for analytical method. In this study, liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was investigated to analyze residue of Pinoxaden (M4), which is defined as pesticide residue in Korea, in foods. METHODS AND RESULTS: Pinoxaden (M4) was extracted followed by acid digestion (2hr reflux with 1N HCl) and pH adjusting (pH 4-5 with 3% ammonium solution). To remove oil, additional clean-up step with hexane saturated with acetonitrile was required to high oil contained sample before purification. HLB cartridge and nylon syringe filter were used for purification. Then, samples were analyzed by LC-MS/MS using reserve phase column C₁₈. Five agricultural group representative commodities (mandarin, potato, soybean, hulled rice, and red pepper) were used to verify the method in this study. The liner matrix-matched calibration curves were confirmed with coefficient of determination (r²) > 0.99 at calibration range 0.002-0.2 mg/kg. The limits of detection and quantitation were 0.004 and 0.01 mg/kg, respectively, which were suitable to apply Positive List System (PLS). Mean average accuracies of pinoxaden (M4) were shown to be 74.0-105.7%. The precision of pinoxaden and its metabolites were also shown less than 14.5% for all five samples. CONCLUSION: The method investigated in this study was suitable to CODEX (CAC/GL 40) and National Institute of Food and Drug Safety Evaluation-MFDS (2017) guideline for residue analysis. Thus, this method can be useful for determining the residue in various food matrixes in routine analysis.

• Korean Journal of Environmental Agriculture
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• v.9 no.1
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• pp.9-13
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• 1990

The dissipation of insecticide fenitrothion(O,O-dimethyl O-4-nitro-m-tolyl phosphorothioate), fungicide IBP(S-benzyl O, O-diisopropyl phosphorothioate), and herbicide butachlor(N-butozymethyl-2-chloro-2', 6'-diethylacetanilide) in flooded soil planted with rice plants was investigated in outdoor pot conditions. The half lives of IBP, butachlor and fenitrothion in the flooding water treated with IBP at 98g, butachlor at 352.8g, and fenitrothion at 100g ai/10a, were 3.6, 1.7 and within 1 day, respectively. The concentration of fenitrothion at 5 days after application was found to be less than 0.0lppm. In the case of IBP and butachlor after 20 days, the concentration was 0.025 and 0.004ppm, respectively. The concentration of fenitrothion, IBP, butachlor in a soil depth of 0-3cm was 0.07, 1.45 and 3.37ppm on the 3rd day after application, and below 0.05, 0.18, 0.39ppm after 7 days, respectively. However, 27 days after application concentration of IBP and butachlor at 0-5cm soil depth resulted in 0.04 and 0.05ppm, respectively. The disappearance of pesticides was remarkably rapid, compared to those in the some soil under the laboratory conditions. Differences in the concentration of IBP in different soil profiles were few, but amounts of butachlor were remarkably higher at 0-2cm soil depth than below 2cm soil depth.

• The Korean Journal of Pesticide Science
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• v.5 no.4
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• pp.40-44
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• 2001

Pesticide actual usage in fruit crop cultivation was surveyed, and usage trends of individual pesticides were evaluated to provide data for the development of indicators of environmental impact. The amount of pesticide used for fruit crops indicated the order of fungicide>insecticide>herbicide unlike the case of paddy rice. The fungicide rate of total usage was 72% in apple cultivation. Top ranking fungicides used on fruits were Mancozeb, Propineb, Thiophanate-methyl and the main insecticides were Mancozeb, Propineb, Thiophanate-methyl. The usuage by formulation types showed the order of WP>EC>SL>SC>SP>WG. Pesticide usage (a.i.) per hectare by different fruits was citrus 48.6kg, apple 27.1kg, pear 18.6kg, persimmon 17.5kg, peach 11.3kg and grape 9.2kg. Comparison of pesticide usage (a.i.,kg/ha) in some fruit crops between Korea and USA indicated that more pesticides were used for citrus, pear and peach in USA than Korea while more pesticides were used in Korea than USA for apple.

• The Korean Journal of Pesticide Science
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• v.4 no.4
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• pp.12-18
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• 2000

In order to artificially reduce the quinclorac residue in aqueous solution and soil, six potential photosensitizers were screened for their effectiveness in enhancing the photodegradation. The degraded amount of quinclorac in distilled water by sunlight was minor compared to that in the dark, indicating that there was little direct photolysis. The photodegradation ratio of quinclorac in methanol was 40.3%. Whereas, the ratios in the presence of photosensitizers PS-1 (aromatic ketone), PS-3 (polycyclic quinone), and PS-6 (inorganic semiconductor) were 96.6, 72.7, and 95.7%, respectively, showing the most photosensitizing effects. In sand, PS-3 was more effective than any other photosensitizer PS-1 (19.6%), PS-3 (64.1%) and PS-6 ($17.9{\sim}19.4%$). five photoproducts of quinclorac in methanol were identified by GC-MS and quinclorac added with the photosensitizer PS-1 gave three photoproducts. Photoproducts with an aldehyde group formed in methanol were confirmed by the reduction of sodium 3,5-dinitrosalicylate in the Lindsay's method. E. crus-galli war. oryzicola was not controlled by the quinclorac residues photodegraded at tile concentrations higher than 30 ppm of the photosensitizer PS-3 in a flooded rice paddy soil. These results indicate that the quinclorac residues in aqueous solution and soil can be degraded efficiently by tile photosensitizers PS-1, PS-3, and PS-6.

• Korean Journal of Weed Science
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• v.16 no.2
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• pp.160-170
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• 1996

Several physiological responses were investigated in plants treated with TOPE as a preliminary step to know its action site. Unlike photo-dependent diphenylethers, herbicidal activity of TOPE appeared slowly and its typical symptoms were both burning of leaf blades and abnormal division of meristem in grasses, Similarly, both leakage of cell electrolytes and the curling of cotyledon margin were also shown in cucumber(Cucumis sativus L.). Biosynthesis of chlorophyll in etiolated cucumber cotyledon was not inhibited directly by treatment of TOPE at low light intensity(5.5${\mu}$ mol $m^{-2}s^{-1}$ PAR) and protoporphyrin IX was not also accumulated. The contents of phytoene, phytofluene and ${\beta}$-carotene were abnormaly increased. Photosynthesis was inhibited only at high concentration. Mitochondrial respiration was inhibited at high concentration but rather increased significantly at 10${\mu}$M of TOPE. However, respiration inhibitors did not alleviate the two symptoms of TOPE in cucumber cotyledon. In the same experiments, using inhibitors of protein or nucleic acid biosynthesis, only one of the two symptoms was alleviated by chloramphenicol and cycloheximide. In contrast, both symptoms were alleviated by actinomycin-D and hydroxyurea, suggesting that nucleic acid metabolism might be preferentially related to the mode of action of TOPE. DNA, RNA and protein contents were accumulated in both cucumber cotyledon and rice (Oryza sativa L.) routs treated with TOPE, and the DNA of them was increased at first. Thus, it is conjectured that TOPE increase nucleic acid metabolism directly or indirectly, and then disturb various metabolic pathways causing abnormal physiological and morphological effects followed by final death.

• Korean Journal of Weed Science
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• v.30 no.4
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• pp.445-453
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• 2010

This study was conducted to investigate herbicidal efficacy and diffusibility of halosulfuron-methyl+mefenacet in water treated with 500 g great granule (GG) and 3 kg granule (GR). The 500 g GG was been spreading on the surface of the water within 6 minutes, 53 seconds, and it's active ingredient was diffused in the water bath of $10m^2$ size between 30 and 60 minutes. In addition, the diffusion of 500 g GG was influenced by moisture contents, so it have to immediately use 500 g GG in paddy fields when it was been unpacked. The herbicidal efficacy of the 500 g GG and 3 kg GR of halosulfuron-methyl+mefenacet was excellent to most weed species, but showed different efficacy for the control of Aneilema keisak and Scirpus juncoides, that was may be distribution pattern of active ingredient as different formulation.