• 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.

• Journal of Plant Biotechnology
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• v.33 no.1
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• pp.57-62
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• 2006

Several methods for determining the response of corn to glyphosate were investigated to provide a fast and reliable method for identifying glyphosate-resistant corn in vivo. Two bioassays were developed. One assay is named 'whole plant / leaf growth assay', in which the herbicide glyphosate is applied on the upper part of 3rd leaf and the growth of herbicide-untreated 4th leaf is measured at 3 day after treatment. in this assay, the leaf growth of conventional corn was inhibited in a dose dependent from 50 to $1600{\mu}g/mL$ of glyphosate and growth inhibition at $1600{\mu}g/mL$ was 55% of untreated control. The assay has the potential to be used especially in the case that the primary cause of glyphosate resistance is related with a reduction of the herbicide translocation. Another assay is named 'leaf segment / shikimate accumulation assay', in which the four excised leaf segments ($4{\times}4mm$) are placed in each well of a 48-well microtiter plate containing $200{\mu}L$ test solution and the amount of shikimate is determined after incubation for 24 h in continuous light at $25^{\circ}C$. In this assay, 0.33% sucrose added to basic test solution enhanced a shikimate accumulation by 3 to 4 times and the shikimate accumulation was linearly occurred from 2 to $8{\mu}g/mL$ of glyphosate, showing an improved response to the method described by Shaner et al. (2005). The leaf segment / shikimate accumulation assay is simple and robust and has the potential to be used as a high throughput assay in the case that the primary cause of glyphosate resistance is related with EPSPS, target site of the herbicide. Taken together, these two assays would be highly useful to initially select the lines obtained after transformation, to investigate the migration of glyphosate-resistant gene into other weeds and to detect a weedy glyphosate-resistant corn in field.

• 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.