• Weed & Turfgrass Science
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• v.7 no.2
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• pp.120-129
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• 2018

This experiment was conducted to find the most suitable crop establishment method and weed management practices for transplanted aman rice in Bangladesh. Rice variety Bangladesh Rice Research Institute (BRRI) dhan44 was used as planting materials where three crop establishment methods ($T_1$: direct wet seeding by drum seeder; $T_2$: hand broadcasting; $T_3$: transplanting) and four weeding options ($W_1$: Hand weeding (HW); $W_2$: BRRI weeder+HW; $W_3$: Herbicide+HW; and $W_4$: no weeding) were tested. Among the crop establishment methods, the highest grain yield ($5.12t\;ha^{-1}$) was obtained with the $T_3$, while the highest benefit cost ratio (BCR) of 2.08 was found in $T_2$. In case of the weed management method, $W_1$ showed superior results on the plant $density/m^2$ (139.66) at 60 days after transplanting (DAT), grain yield ($4.97t\;ha^{-1}$), and BCR (2.03). On the other hand, the highest plant dry matter (36.20 g) at 60 DAT and the highest yield ($6.10t\;ha^{-1}$) were obtained in a $T_3W_1$ combination. The results of this study show that the productivity of rice during aman season could be most significantly increased with the use of transplanting ($T_3$) alone, hand weeding ($W_1$) alone, or a combination of the two methods ($T_3W_1$).

• Korean Journal of Plant Resources
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• v.19 no.5
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• pp.612-616
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• 2006

In recent years, there has been increasing concerns in gene flow from GM crops to wild or weedy relatives as a potential risk in the commercialization of GM crops. To access the possibility of the environmental impacts by GM rice, small-scale experiments of gene transfer were carried out. Herbicide and drought stress resistant GM rice and non-GM rice Nakdongbyeo, wild rice Oryza nivara, and weedy rice Sharebyeo were used for artificial pollination experiments and bar gene was used as a tractable marker after pollination. The harvested putative hybrid seeds after artificial pollination were germinated and true hybrid plants were selected by basta treatment. The hybrid plants were verified again by PCR amplification of bar and trehalose-6-phosphate phosphatase (TPP) genes and RAPD PCR analysis.

• Korean Journal of Weed Science
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• v.7 no.2
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• pp.179-185
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• 1987

Laboratory studies were conducted to evaluate safening effect of CGA 123'407 (4,6-dichloro-2-phenyl-pyrimidine) against pretilachlor, butachlor, and benthiocarb in rice plants. Butachlor and benthiocarb at 50 ppm or higher concentrations significantly inhibited rice growth and pretilachlor gradually inhibited growth of rice plants with increase in concentration starting from 0.5 ppm. CGA 123'407 at 0.1 ppm or higher concentrations was effective in reducing injury of rice plants when butachlor and benthiocarb were applied at rate of 10 ppm. Rice injury from pretilachlor at 10 ppm was also reduced by addition of CGA 123'407 at 0.25 ppm or higher concentrations Herbicidal activity of pretilachlor, butachlor, and benthiocarb was not affected by mixture treatments of CGA 123'407.

• Korean Journal of Agricultural Science
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• v.41 no.2
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• pp.85-99
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• 2014

Sulfonylurea (SU)-resistant weeds of eight annual weeds, Monochoria vaginalis, Scirpus juncoides and Cyperus difformis, etc., and four perennial weeds, Scirpus planiculmis, Sagittaria pigmaea, Eleocharis acicularis and Sagittaria trifolia as of 2013 since identification Monochoria korsakowii in the reclaimed rice field in 1998. And the resistant Echinochloa oryzoides to ACCase and ALS inhibitors has been confirmed in rice fields of the southern province, Korea in 2009. In the beginning, the M. vaginalis, S. juncoides and C. difformis of these SU-resistant weeds were rapidly and individually spreaded in different fields, however, these resistant weeds have been occurring simultaneously in the same filed recently. The resistant biotype by weed species demonstrated about 10-to 1,000-fold resistance, based on $GR_{50}$ values of the SU herbicides tested. And the resistant biotype of E. oryzoides to cyhalofop-butyl, pyriminobac-methyl, and penoxsulam was about 14, 8, and 11 times more resistant than the susceptible biotype base on $GR_{50}$ values. The products and applied area of SU-included herbicides have been increased rapidly, and have accounted for about 69% and 96% in Korea, respectively. In Korea, the main cause of SU-resistant weed is extensive use of these herbicides. The top ten herbicides by applied area were composed of all SU-included herbicides by 2003. The concentrated and successive treatment of ACCase and ALS inhibitors for control of barnyardgrass in rice led up to the resistance of E. oryzoides. Also, SU-herbicides like pyrazosulfuron-ethyl and imazosulfuron which effective to barnyardgrass can be bound up with the resistance of E. oryzoides. The ALS activity isolated from the resistant biotype of M. korsakowii to SU-herbicides tested was less sensitive than that of susceptible biotype. The concentration of herbicide required for 50% inhibition of ALS activity ($I_{50}$) of the SU-resistant M. korsakowii was 14-to 76-fold higher as compared to the susceptible biotype. No differences were observed in the rates of [$^{14}C$]bensulfuron uptake and translocation. Acetolactate synthase (ALS) genes from M. vaginalis resistant and susceptible biotypes against SU-herbicides revealed a single amino acid substitution of proline (CCT), at 197th position based on the M. korsakowii ALS sequence numbering, to serin (TCT) in conserved domain A of the gene. Carfentrazone-ethyl and pyrazolate were used mainly to control SU-resistant M. vaginalis by 2006 in Korea. However, the alternative herbicides such as benzobicyclone, to be possible to control simultaneously the several resistant weeds, have been developing and using broadly, because the several resistant weeds have been occurring simultaneously in the same fieled. The top ten herbicides by applied area in Korea have been occupied by products of 3-way mixture type including herbicides with alternative mode of action for the herbicide resistant weeds. Mefenacet, fentrazamide and cafenstrole had excellent controlling effects on the ACCase and ALS inhibitors resistant when they were applied within 2nd leaf stage.

• The Korean Journal of Pesticide Science
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• v.8 no.1
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• pp.63-70
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• 2004

Sulfonylurea(SU)-resistant Monochoria korsakowii has resently been found in rice fields in Korea. A quick, practical and accurate test of confirming herbicide resistance is necessary to take timely management decision. This article describes a rapid reliable assay to detect SU-resistant biotype of Monochoria korsakowii. Up to now, the resistance to SU has been usually checked by application seedlings with herbicide. This application technique is time consuming and not practical. Therefore, we have developed efficient, rapid and practical diagnosis which allow easy detection of the SU-resistant Monochoria korsakowii by survival rate and regenerated plant length to herbicide application after cutting plants $0.5\sim1cm$ from the planted surface. This new rapid diagnosis can determine the SU resistance of the Monochoria korsakowii within 7 days at least. If the resistance of Monochoria korsakowii is identified by the rapid diagnosis, the selection of herbicide according to the stages of plants for the effective control is very important. The resistant biotype which treated with SU herbicide-based mixtures survived from the fields could effectively be controlled by soil application of butachlor+pyrazolate GR or by foliar application of the mixtures of bentazone SL and 2,4-D SL.

• Korean Journal of Soil Science and Fertilizer
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• v.13 no.1
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• pp.45-51
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• 1980

The effects of propanil, MCPA; 2, 4 5-T and silvex on the numder of new root and tiller on Taichung Native 1, Caloro, PI 245717 and Bluebonnet 50 by root administration and foliar spray at 10 levels of concentration were investigated. Phenoxy herbicides changed the growth pottern in the way of increased number of tillers and new roots rather than plant height or root length. It was suggested that MCPA is only possible to increase tillering around applicable range. Silvex stimulated tillering at higher level than that required to stimulate new root formation. Varietal response on herbicides were different along with herbicide feeding part. There was trends that the higher nitrogen response varieties also have a greater response to stimulating effect of herbicide. Propanil had no effect on growth and no injury even about 20 times of higher concentration of phenoxy herbicide.

• Weed & Turfgrass Science
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• v.6 no.4
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• pp.345-349
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• 2017

Herbicides are important weed control tools for increasing crop yields and the efficiency of crop production. As the use of herbicides increases, the occurrrence of herbicide-resistant weeds has been an increaing problem. In Korea, since the first occurrence of acetolactate synthase (ALS) inhibitor resistant Monochoria korsakowii was reported in the Seosan reclaimed paddy field in 1998, resistance has been reported in 14 weed species, including Echinochola spp. and their populations are gradually increasing. The objective of this study is to investigate the nationwide occurrence of ALS and Acetyl-CoA Carboylase inhibitor resistant Echinochloa spp. in Korea. In 2013, 2014, and 2015, we collected 594 accessions of Echinochloa spp. in Korean rice fields except for Jeonnam and Chungbuk provinces. They were then treated with the recommended rates of penoxsulam and cyhalofop-butyl. We harvested seeds from 45 accessions of E. oryzicola in the case of cyhalofop-butyl treatment. Also, 44 and 46 accessions of E. oryzicola and E. crus-galli survived and their seeds were harvested after penoxsulam treatment. Twenty accessions of E. oryzicola survived from both herbicides inferring possible multiple resistance. Two accessions out of 20 inferred from possible multiple resistance survived after cyhalofop-butyl treatment at a dose of $500ga.i.ha^{-1}$. Seeds of herbicide resistant populations will be provided and utilized for further research.

• Korean Journal of Microbiology
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• v.27 no.3
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• pp.285-290
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• 1989

The biololgical effect of the preemergence rice field herbicide, butachlor(commercial name, Machete) on purple nonsulfur photosynthetic bacterium Rhodospirillum rubrum KS-301 has been studied under cultural conditions. Bacterial growth showed a tendency to decline according to the degree of the concentration of butachlor until $10^{-3}$ M and slmost stopped at $10^{-2}$M. The growth inhibitory action at $10^{-3}$M of butachlor was evident (4.2-18.7% inhibition of growth rate) but had little effect in nitrogen fixation. Conversely, there was a little enhancement effect(1%) in pyruvate, dinitrogen gas growing cultures. At concentration of $10^{-3}$ M, instead of spiral form, rod shapes were observed through phase contrast microscope and instead of vesicular intracytoplasmic membrane, irregular tubular forms were observed through electron microscope. Alkaline pH value slightly reversed tha inhibitory action of butachlor.

• Korean Journal of Weed Science
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• v.31 no.4
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• pp.401-404
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• 2011

Bromobutide, a paddy field herbicide, can effectively control annual and perennial weeds. It has an excellent weeding effect especially against Monochoria vaginalis and Scirpus juncoides etc. When it is mixed with other herbicides controlling weed spectrum and application timing can be broaden. Bromobutide has stable weeding effects regardless of field and weather conditions, and there is almost no phyototoxic effects to rice.

• Korean Journal of Agricultural Science
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• v.41 no.2
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• pp.113-117
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• 2014

This study was conducted to evaluate the efficacy of benzobicyclon mixtures by using Remote-controlled aerial application (RCAA) to control annual and perennial weeds in rice paddy field. Eight annual weed species including Echinochloa crus-galli L. and three perennial weeds were dominated in the experimental field. Application of benzobicyclon mixtures using RCAA was highly effective to control both annual and perennial weed species. When compared with untreated control, no visual injuries were detected at single and double dosage of benzobicyclon mixtures. Finally, rice yield in the benzobicyclon mixtures was as much as that in the hand weeding. This study indicates that benzobicyclon mixtures using RCAA can be applied to control both annual and perennial weed species in rice paddy field.