• Korean Journal of Agricultural Science
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• v.44 no.1
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• pp.1-15
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• 2017

In major field crops, synthetic herbicides have been used to control weeds worldwide. Globally, herbicide resistance in weeds should be minimized because it is a major limiting factor for food security. Cross resistance can occur with herbicides within the same or in different herbicide families and with the same or different sites of action. Multiple resistance refers to evolved mechanisms of resistance to more than one herbicide (e.g., resistance to both ALS-inhibitors and ACCase-inhibitors) and this resistance was brought about by separate selection processes. Target site resistance could occur from changes at the biochemical site of action of one herbicide. Non target site resistance occurs through mechanisms which reduce the number of herbicide molecules that reach the herbicide target site. There are currently 480 unique cases (species ${\times}$ site of action) of herbicide resistance globally in 252 plant species (145 dicots and 105 monocots). To date, resistance in weeds has been reported to 161 different herbicides, involving 23 of the 26 known herbicide sites of action. Finally, it can be concluded that we can protect crops associated to herbicide resistant weeds by applications of biochemical, genetic and crop control strategies.

• Korean Journal of Agricultural Science
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• v.46 no.2
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• pp.405-416
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• 2019

Weeds are a serious problem in crop production. Use of synthetic herbicides is rapidly increasing in weed management worldwide including Korea. Herbicide application reduces the time spent on weed control. However, the evolution of resistance to herbicides in weeds has become widespread as a natural response to selection pressure imposed by agricultural management activities. If an herbicide with the same mechanisms of action is used repeatedly and intensively, it can rapidly select for a weed biotype that shifts toward difficult-to-control becoming a more tolerant weed and lead to the evolution of herbicideresistant weeds. Moreover, agricultural and biological factors have an important role in the development of herbicide-resistant weed populations. Mitigating the evolution of herbicide resistance in weeds relies on reducing selection through the diversification of weed control techniques. The resistance management of weeds in the future will strongly depend on intensive cropping systems. The current situation of intensive cropping systems with their heavy reliance on the efficacy of chemical weed control will not lead to significant containment of this problem. Therefore, management strategies need to overcome the further spread of herbicide resistance in weeds in Korean crop production. This review presents the current information on herbicide resistance in Korea and factors controlling the development of herbicide resistant weeds.

• Weed & Turfgrass Science
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• v.7 no.3
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• pp.201-208
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• 2018

This study was conducted to investigate the occurrence and distribution of herbicide resistant weeds at rice fields in Chungnam province of Korea in 2017. Herbicide-resistant weeds occurred in 64,782 ha, which comprise 47.0% of the total paddy field area of Chungnam province. The infested area of herbicide resistant weeds was estimated in Seosan-si (11.9%), Nonsan-si (11.1%), Dangjin-si (10.9%), Boryeong-si (9.2%) and Asan-si (7.8%). The most dominant herbicide resistant weeds in rice fields were Monochoria vaginalis, followed by Lindernia dubia, Schoenoplectus juncoides, Echinochloa oryzicola, Cyperus difformis and Sagittaria trifolia. Herbicide resistant M. vaginalis, L. dubia, and S. juncoides occurred throughout Chungnam province, and herbicide resistant S. trifolia was only found in Dangjin-si. Compared with the 2011 survey, the infested area of herbicide-resistant weeds decreased, but the incidence rates were similar. The herbicide rotation with different modes of actions across growing seasons is recommended to control herbicide-resistant weeds in the infested fields. It is necessary to monitor herbicide resistance regularly and conduct integrated herbicide resistance management in this area.

• Korean Journal of Weed Science
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• v.4 no.1
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• pp.96-106
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• 1984

Changes in weed floras and development of plant resistance to herbicides seemed to be closely related with increased and repeated use of herbicides. Herbicide use increased from 5% of the total consumption of pesticide in 1950 to 45% in 1976 in world basis. About 200 herbicides have been introduced to agriculture so as to control about 206 weed species which have been recorded important to human beings. In Korea, there was about 351 times in increased use of herbicides from 1966 to 1982. Interspecific selection by herbicide is mainly responsible for changes in weed floras and resulted in varying tolerance or susceptibility to herbicides, together with the changes of agricultural practices. The present trend toward continuous cereal cultivation throughout world will lead to type of changes in weed floras favorable to therophyte which can survive under unfavorable conditions as seeds rather than the types of geophyte which can survive unfavorable seasons as buds placed below soil surface. However, geophyte such as Sagitaria pygmaea, and Scirpus jurtcoides, and Cyperus rotundus and Cynodon dactylon in temperate warm climate become severe paddy weeds, presumably because of the removal of annual weeds by herbicides. Since differential tolerance to 2,4-D was firstly reported in Agrostis stolofera, about 30 species of weeds in 18 genera are presently known to have developed resistance to triazine herbicides. Resistance of weed biotypes to triazine herbicide is not mainly due to limited absorption and translocation or to the difference in metabolism, but is the result of biochemical changes at the site of metabolic activity, such as a loss of herbicide affinity for triazine binding site in the photosystem II complex of the chloroplast membrane. Genetical study showed that plastid resistance to triazine was wholly inherited through cytoplasmic DNA in the case of Brassica campestris. Plant tissue culture method can be utilized as an alternate mean of herbicide screening and development of resistance variants to herbicides as suggested by Chaleff and Parsons. In this purpose, one should be certain that the primary target process is operational in cell culture. Further, there are a variety of obstacles in doing this type of research, particularly development of resistance source and it's regeneration because cultured cells and whole plants represent different developmental state.

• Korean Journal of Agricultural Science
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• v.42 no.4
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• pp.335-339
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• 2015

This paper reviews current status of weed science in Japanese regional agricultural systems based on the 54th Annual Meeting of the Weed Science Society of Japan. About 300 researchers from 5 countries including Korea participated in the Conference and presented 100 papers in research areas. This congress has an purpose to discuss new troubles, findings and results of weed science. Weed science faces big challenges such as increase in herbicide-resistant weeds, gene-flow from transgenic crops, and invasive weeds. Major research topics were invasive weeds and their ecology, allelopathy, weed management in paddy field, weed management in field crops, and herbicide resistance. Weed control and herbicide resistance management in paddy field were a main object of research. To prevent the increase of problematic weeds and to overcome food crisis, the importance of weed-related researches has been raised. Therefore it is expected that various weed management systems and control of herbicide resistant weeds should be studied continuously in the weed science.

• Weed & Turfgrass Science
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• v.3 no.1
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• pp.1-5
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• 2014

This paper reviews current status of weed science in Asian-Pacific regional agricultural systems based on the 24th Asian-Pacific Weed Science Society Conference. About 190 researchers from 16 countries including Korea participated in the Conference and presented 160 papers in 11 research areas. Major research topics were invasive weeds and their ecology, allelopathy, weed management in paddy field, weed management in field crops, and herbicide resistance. Because rice is a major food crop in Asian countries, weed control and herbicide resistance management in paddy field were a main object of research. Weed control in maize, soybean and wheat has also been studied continuously. To prevent the increase of problematic weeds and to overcome food crisis, the importance of weed-related researches has been raised. Therefore it is expected that various weed management systems and control of herbicide resistant weeds should be studied continuously in the future.

• Weed & Turfgrass Science
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• v.2 no.3
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• pp.221-229
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• 2013

This paper reviews current status of weed control practices in herbicide-resistant crops to examine weed management strategies in cope with cropping herbicide-resistant crops in the near future. Herbicide-resistant crops were rapidly adopted weed management technologies due to broad-spectrum weed control without crop injury. Transgenic glyphosate-resistant cultivars in soybean, corn, canola, and cotton were adopted to manage weeds at lower cost in a simplified weed management system. Dual stack crops with glyphosate and glufosinate resistance were developed to control glyphosate resistant weeds in corn, soybean and cotton. New multiple herbicide-resistant crops with resistance to glyphosate and glufosinate, acetolactate synthase (ALS) inhibitors, synthetic auxin herbicides, 4-hydroxyphenyl pyruvate dioxygenase (HPPD) inhibitors or acetyl Coenzyme A carboxylase (ACCase) inhibitors will expended the utility of existing herbicide technologies to manage the evolution of resistant weeds. However, herbicide resistant crops alone cannot solve weed problems and thus studies on diverse weed managements using an array of alternating herbicides of mode of action, mechanical, and cultural practices are needed for integrated weed management systems in the future.

• The Korean Journal of Pesticide Science
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• v.12 no.1
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• pp.1-8
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• 2008

The widespread and diverse sulfonylurea (SU) resistance problem has found in Korea, where one-shot-treatment herbicides such as pylazosulfuron/molinate and bensulfuron/molinate have been used continuously since 1989. The SU-resistant weeds of 7 annual weeds and 3 perennial weeds as of 2008 have confirmed in paddy fields in Korea. An effective management to SU-resistant weeds requires an integrated approach toward the weed control system, in particular, as to the drastic changes of herbicides development. Recent trend of new paddy herbicides in Japan has been developing to maximize the management of SU-resistant weeds. In the future, it is expected that the development of paddy herbicides in Korea is likely to be shifted toward the new "one-shot-treatment" included with herbicides of over 3-ways to maximize the control of resistant weeds. Bromobutide and carfentrazone are effective against sedges and broad-leaved weeds, respectively, and benzobicyclone and pyrimisulfam are effective against sedges and broad-leaved weeds.

• Korean Journal of Weed Science
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• v.32 no.3
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• pp.170-173
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• 2012

China is one of most important countries for production and consumption of herbicide. Although the chemical weeding technology promoted the development of agricultural modernization in Chinese, it led to the negative effects to agriculture. In particular, the weeds resistant herbicide in paddy field had been serious challenge for safe production of rice. The chemical control technology for weed resistant herbicide with effective, low cost and safety characteristic will be key problem being solved in futhure.

• Weed & Turfgrass Science
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• v.5 no.3
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• pp.105-110
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• 2016

This paper provides the current status of weed science and prospects for the development of weed science based on the research trends presented at the 7th International Weed Science Conference in 2016. Approximately 520 researchers from 59 countries, including Korea, participated in the conference and presented 625 papers in nine research areas. Major research topics were herbicide resistance, weed ecology, weed management in agricultural and non-agricultural lands, herbicide spray technology, and non-chemical weed control. Studies on herbicide resistance presented more than 30% of all papers presented. Particularly, resistance to non-selective herbicides, such as glyphosate and glufosinate-ammonium, and non-target sites of resistance mechanisms were the main subjects of the herbicide resistance research area. Moreover, the conference focused on research concerning herbicide resistant weeds of staple crops of the world (corn, wheat, and rice). Arylex was introduced as a new compound which has a mode of herbicidal action similar to synthetic auxin. Three compounds being developed as HPPD inhibitors were studied for ways to reduce their toxicity and tested as mixed with safeners. Additionally, parasitic weeds, which are not native to Korea, are an expanding research subject in the world. Although 45 years have passed since the first report of herbicide resistance in 1970, herbicide resistance remains a serious problem in most intensive cropping systems of the world and will continue to be a major area of study in the future.