• Weed & Turfgrass Science
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• v.5 no.4
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• pp.191-195
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• 2016

Tefuryltrione is a new hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor, which has been recently registered for the use for paddy rice, Korea. Dose-response studies were conducted to compare rice safety and weed control efficacy of tefuryltrione against Eleocharis kuroguwai. When rice and E. kuroguwai were applied at a range of doses of tefuryltrione, $GR_{90}$ values (the dose required to inhibit weed growth by 90%) of E. kuroguwai were $82.38-93.39g\;a.i.\;ha^{-1}$ in two independent experiments. The $GR_{10}$ values (the dose required to inhibit rice growth by 10%) of tefuryltrione for rice were $297.77-471.54g\;a.i.\;ha^{-1}$. As a result, the selectivity indices ($GR_{10}$ for $rice/GR_{90}$ for E. kuroguwai) of tefuryltrione were 3.19-5.72. Therefore, these results demonstrate that tefuryltrione has a relatively high selectivity between rice and E. kuroguwai with a high herbicidal activity against E. kuroguwai and a good rice safety.

• Korean Journal of Weed Science
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• v.5 no.1
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• pp.43-49
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• 1985

This study was conducted to investigate the existance of dormancy in newly collected tubers of Eleocharis kuroguwai Ohwi from paddy fields and to determine the effect of various growth regulators on the bud sprouting and tuberization of E. kuroguwai. The maximum percent sprouting of E. kuroguwai collected at every month during winter was less than 60% regardless of varied collection tunes until 50 days after incubation, suggesting the presence of dormancy in E. kuroguwai tubers. This dormancy was markedly broken as the time went by, probably due to the exposure of tubers the extremly low temperature. The treatment of $BA10^{-3}M$ and $BA10^{-3}+GA10^{-6}M$ increased bud sprouting about 10 and 11 times, respectively, than that of the untreated control indicating that BA seems to be one of the most effective agents among the growth regulators used on the bud sprouting of E. kuroguwai. Foliar application of BA increased tuberization of E. kuroguwai by an average of 34.4% as compared with the untreated control. The highest increase, 39.8% was obtained with BA treatment at $10^{-5}M$.

• Korean Journal of Weed Science
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• v.9 no.1
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• pp.34-38
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• 1989

This study was conducted to investigate the tuberization time and the control method for Eleocharis kuroguwai Ohwi. The control methods were compared the shoot cutting and bentazon treatment for E. kuroguwai with untreatment. The initial tuberization time of E. kuroguwai, when E. kuroguwai was planted and without rice planted, was about August 18th and 10th, respectively. When the shoot of E. kuroguwai was cut, the regrowth vigour scarcely revived for the cutting on September 12. The least tuberization of E. kuroguwai, when E. kuroguwai was just planted and planted with rice plant, were on August 28 and August 3 to the top cutting of E. kuroguwai, respectively. Bentazon treatments from July 19 to August 3 hardly induced tuberization of E. kuroguwai, while as the delay of bentazon treatment time the tuberization of E. kurguwai was little by little increased.

• Korean Journal of Weed Science
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• v.4 no.2
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• pp.125-129
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• 1984

Emergence and early growth of Eleocharis kuroguwai, Potamogeton distinctus, and Sagittaria pygmaea were examined at 10, 14, 18, 22, 26, and $30^{\circ}C$ of soil temperatures using soil temperature gradient bath. Eleocharis kuroguwai emerged at $14^{\circ}C$ or higher temperature and % emergence was increased as soil temperature increased up to $26^{\circ}C$ but decreased at $30^{\circ}C$. Percentage of emergence in Potamogeton distinctus was very low at $10^{\circ}C$ but most of them were emerged at $14^{\circ}C$ or above. Emergence rate was faster as soil temperature increased. Percentage of emergence in Sagittaria pygmaea was increased until 10 days after planting as soil temperature increased but final percentage of emergence was 100% at all temperature. Number of days required for 80% emergence was shortened as soil temperature increased and Eleocharis kuroguwai and Potamogenton distinctus required longer duration to emerge compared to Sagittaria pygmaea. Eleocharis kuroguwai and Potamogeton distinctus required higher accumulated soil temperature for emergence compared to Sagittaria pygmaea. Optimum soil temperature for early growth after emergence of Eleocharis kuroguwai, Potamogeton distinctus, and Sagittaria pygmaea were 26, 18-22, and 18-$26^{\circ}C$, respectively.

• Korean Journal of Weed Science
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• v.30 no.2
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• pp.94-102
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• 2010

Field and pot experiments were conducted to investigate seedling emergence and early growth of Eleocharis kuroguwai panted on different dates. Non-linear regression analyses of observed data against effective accumulated temperature (EAT) with the Gompertz model showed that the Gompertz model works well in describing seedling emergence and early growth of E. kuroguwai regardless of planting date and soil burial depth. EATs required for 50% of the maximum seedling emergence of E. kuroguwai planted at 1, 3 and 5 cm soil burial depth in the pot experiment were estimated to be 54.5, 84.0 and $118.0^{\circ}C$, respectively, and $56.7^{\circ}C$ when planted at 1 cm in the field experiment. EATs required for 50% of the maximum leaf number of E. kuroguwai planted at 1, 3 and 5 cm soil burial depth in the pot experiment were estimated to be 213.3, 249.0 and $291.6^{\circ}C$, respectively, and $239.5^{\circ}C$ when planted at 1 cm in the field experiment. Therefore, models developed in this study thus predicted that if rotary tillage with water is made on 27 May under $+2^{\circ}C$ elevated temperature condition, dates for 50% of the maximum seedling emergence, 5 leaf stage and 5 cm plant height of E. kuroguwai buried at 3 cm soil depth were predicted to be 2 June, 10 June and 12 June. These dates are 1 day earlier for the seedling emergence and 3 days earlier for the early growth as compared with current temperature condition, suggesting that earlier application of herbicides is required for effective control of E. kuroguwai.

• Korean Journal of Weed Science
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• v.12 no.1
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• pp.46-51
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• 1992

The survey of weed population in paddy field was carried out to invegstigate the weed group on 340 fields in Kyonggi Area in 1991. The weed species observed include 4 species of grasses, 7 species of sedges, and 14 species of broadleaf weeds, and the ratio of annual weed vs perennial weed was 25 : 75. Major dominant weed species were Eleocharis kuroguwai, Sagitaria trifolia, Echinochloa crusgalli and Cyperus serotinus. The dominant weed species in South Plain Region were Echinochloa crusgalli, Eleocharis kuroguwai, Sagitariu trifolia, Cyperus strotinus, in West Coast Region were Eleocharis kuroguwai, Sagitaria trifolia, Echinochloa crusgalli, Cyperus serotinus, in East Interior Region were Eleocharis kuroguwai, Sagitaria trifolia, Echinochloa crusgalli, Cyperus difformis and were Sagitaria trifolia, Eleocharis kuroguwai, Echinochloa crusgalli and Monochoria vaginalis in North Region. The dominant weed species in Normal and Poorly drained soil were Eleocharis kuroguwdi, Sagitaria trifolia, Echinochloa crusgalli and Cyperus serotinus and were Scirpus maritinus, Cyperus serotinus, Echinochlod crusgalli and Myriophyllum verticillatum in Saline Soil. More and many weeds were growing in single cropped field than double cropped field.

• The Plant Pathology Journal
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• v.18 no.3
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• pp.152-155
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• 2002

Epicoccosorus nematosporus was detected in all 22 counties surveyed, but the frequency of occurrence of fingerprint stem blight disease (FSBD) on Eleocharis kuroguwai caused by the fungus varied with fields and regions. The disease occurred more frequently in mountain areas than in plain areas. E. nematosporus was detected in less than 20% of plain areas such as Cimjae and Milyang, whereas, it occurred in 40-60% of mountain areas such as Sangiu and Jangsoo. In Milyang, mean temperature in July to August 1993 ranged from 17 to $27^{\circ}C$ with 14.3 h of dew period. Meanwhile, in the mountain area such as Sangiu, Gyeongbook, temperature ranged from 17 to $24^{\circ}C$ with 16.1 h of dew period. Plant mortality was 61% in Milyang and 82% in Sangju. Underground tuber formation was highly suppressed at 16 and 33 tubers per plot in Sangju and Milyang, respectively. In 1992 and 1995, plants infected ranged from 40 to 78% in July to September. This sharply decreased to an average of 15% in 1999.

• Korean Journal of Weed Science
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• v.10 no.3
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• pp.186-191
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• 1990

This experiments was conducted to investigate the dormancy of Eleocharis kuroguwai tuber in the earth and the influence of seeding time and depth on the emergence of Eleocharis kuroguwai. The tuber of Eleocharis kuroguwai on underground was formed the most amount between 10cm and 15cm layer and formed the second a lot of tuber in the soil layer between 5cm and 10cm, the third between the surface of the earth and 5cm, the least between 15cm and 20cm. The total mean emergence of tuber was 78%, and the dormant tuber was approximately 22% of total tuber formed during a year in the earth. The distribution of dormant tuber under the ground was about 42% between 15cm and 20cm, 39% between 10 cm and 15cm, 14% between 5cm and 10cm, and 5% between the surface of the earth and 5cm. The dormancy percent of tuber formed at each soil layer was about 60% between 15cm and 20cm, 21% between 10cm and 15cm, 12% between 5cm and 10cm, and 7% between the surface of the earth and 5cm. The emergence days of the tuber seeded at low layer was short, and the emergence rate was high, The tuber was formed much more on seeding at May 30th than June 30th.

• Weed & Turfgrass Science
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• v.5 no.4
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• pp.219-224
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• 2016

This study was conducted to investigate the ecology of weed occurrence and to establish an economical paddy field weed control system for direct-seeded rice on water. The main problem weed among annual and perennial weeds was Eleocharis kuroguwai. The control effect of E. kuroguwai was low by the application of azimsulfuron + carfentrazone-ethyl + pyriminobac-methyl at the early stages of rice in directly seeded paddy fields, but most annual weeds including Echinochloa crus-galli were controlled. Also, the additional application of pyrazosulfuron-ethyl + thiobencarb GR at 20 days after first treatment or of bentazone SL at 43 days after the first treatment effectively controlled E. kuroguwai. Tuber formation of E. kuroguwai was inhibited by the additional application of pyrazosulfuron-ethyl + thiobencarb by 84%, but the dormancy rate of old tubers of E. kuroguwai under the soil was higher than that of E. kuroguwai tubers following single application of azimsulfuron + carfentrazone-ethyl + pyriminobac-methyl at the early stages of rice. Tuber formation was inhibited by the additional application of bentazone by approximately 87%, and the old tuber dormancy rate was low in the bentazone treatment. High amounts of old dormant tubers of E. kuroguwai were found in the weedy plots.

• The Plant Pathology Journal
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• v.18 no.2
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• pp.81-84
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• 2002

Effects of temperature and dew period on sporulation of a mycoherbicide, Epicoccosorus nematosporus, on the lesion of its host, Eleocharis kuroguwai were determined. Conidia formation was first observed after 10 days on plants incubated for either 12 or 16 h in a dew chamber at 28$^{\circ}C$; 16 h dew period resulted in more conidia formation. As the dew period was decreased to less than 8 h, fewer conidia formed. Conidial production was most abundant at 28$^{\circ}C$ and produced as much as 3.3$\times$10$^4$conidia per lesion, while 0.1$\times$10$^3$and 2.3$\times$10$^3$conidia per lesion were produced at 16$^{\circ}C$ and 36$^{\circ}C$, respectively. Alternating temperature regimes, i.e., 30/15, 30/20, 28/20, and 28/15$^{\circ}C$ (day/night) were much better than constant temperature, i.e., 30/30, 28/28/, and 20/2$0^{\circ}C$ for sporulation. In the second sporulation, there were as much as 3.1$\times$10$^4$conidia per lesion (ca. <50% of the first sporulation). Then, sporulation dropped sharply to 6.2$\times$10$^2$conidia per lesion in the third sporulation. Results of this study suggest that temperature combined with dew period is the primary limiting factor in the use of E. nematosporus as a mycoherbicide off, kuroguwai.