• Weed & Turfgrass Science
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• v.7 no.1
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• pp.46-53
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• 2018

This study was conducted to establish standard fresh weight data about the minimum amount of occurred weeds at untreated paddy fields, upland fields and orchard fields (including non-cultivated land) in 10 areas. The amount of occurred weeds in each area was compared fresh weight with dry weight. The average percentage for ratio of dry weight to fresh weight in paddy fields was concluded to be 14.8% of Echinochola crus-galli, 12.5% of annual weeds (including Echinochola crus-galli), and 13.9% of perennial weeds. The average percentage for ratio of dry weight to fresh weight in upland fields was concluded to be 20.1% of annual weeds and in orchard fields was concluded to be 18.4% of annual and perennial weeds. According to the research, standard fresh weight about the minimum amount of occurred weeds at untreated paddy fields was proposed to $210g\;m^{-2}$ of Echinochola crus-galli, $400g\;m^{-2}$ of annual weeds (including Echinochola crus-galli), and $220g\;m^{-2}$ of perennial weeds. Standard fresh weight about the minimum amount of occurred weeds at untreated upland fields was proposed to $250g\;m^{-2}$ of annual weeds and at untreated orchard fields was proposed to $550g\;m^{-2}$ of annual and perennial weeds.

• Korean Journal of Plant Resources
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• v.9 no.1
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• pp.47-54
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• 1996

To search herbicidal compounds in Pulsatilla koreana Nakai, methanol extract of P. koreana roots was purified by sequences of XAD-7 column chromatography, silica gel adsorption column chromatography, silica gel flash column chromatography, preparative layer chromatography and preparative high performance liquid chromatography(Prep, HPLC).The final Prep. HPLC gave two herbicidally-active fractions. These fractions treatment at 100ppm inhibited the root length of Echinochloa crus-galli seedlings by 48% and 60% as compared with the control, respectively. Components in the two active fractions were analyzed by GC-MS Spectrometry. These compounds, which were isolated from P. koreana roots, were identified as several fatty esters, hydrocarbons, squalene, evidonol, and a diazepin analogue.

• 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.