• Korean Journal of Environment and Ecology
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• v.20 no.3
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• pp.311-318
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• 2006

In an estuary, ecological dynamic is modified for a long time and memorized in soils and landscapes. As landscape memory, ecological motif is defined with dominance and rarity of vegetation. The purpose of the study is to investigate the existing vegetation character and to propose the ecological motif of this area. The present salt-water plants, community species composition and constancy degree around the estuary in Buandam watershed Buan-gun, Jeollabuk-do were analyzed. The results are as follows. The flora of the salt-water plants was listed as 16 taxa; 6 families,13 genera,14 species and 2 varieties. 5 taxa were Gramineae, 4 taxa Chenopodiaceae, and 4 taxa Comrositae. The salt-water plant communities are a total of 10 communities as listed; Zoysia sinica-Artemisia scoparia community, Phacelurus latifolius community, Artemisia scoparia Cnidium japonicum community, Limonium tetragonum -Artemisia scoparia community, Artemisia scoparia community, Suaeda japonica community, Elymus dahuricus community, Suaeda asparagoides community, Zoysia sinica community, and Zoysia sinica-Suaeda japonica community. Analyzed by the community classification species class of constancy degree, Phacelurus latifolius, Cnidium japonicum, Limonium tetragonum, Suaeda japonica, Elymus dahuricus and Suaeda asparagoides belong to I, Zoysia sinica and Artemisia scoparia to II. Elymus dahuricus, Setaria viridis var. pachystachys, Echinochloa crusgalli var. oryzicola, Phacelurus latifolius, Atriplex gmelini, Salicornia herbacea, Calystegia soldanella and Aster tripolium belong to the accompaniment species to I: Zoysia sinica, Suaeda asparagoides, Artemisia capillaris to II; Suaeda japonica, Artemisia scoparia to III ; Cnidium japonicum to IV: Limonium tetragonum, Artemisia fukudo to V. And the ecological motif is the Phacelurus latifolius community.

• Korean Journal of Weed Science
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• v.18 no.4
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• pp.341-347
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• 1998

This study was carried out to investigate the effect of U-Granule formulation of molinate(S-ethylhexaphdro-1H-azepine-1-carbothioate) mixtures in green house and paddy field, Five minutes were taken for U-Granule to spread out 7m in irrigated water of direct seeded on flooded paddy surface. The concentration of active ingredient of molinate in molinate U-Granule application was similar to molinate+simetryn U-Granule application. But weeding effect of molinate+simetryn U-Granule on Echinochlor crus-galli was 23% higher Than single application of molinate at 7m from application point. Bioefficacy of molinate+simetryn+imazosulfuron U-Granule on control of Echinochloa crus-galli was higher than that of molinzte+imazosulfuton U-Granule, but those effect on Eleochairs kuroguwai was not significantly different. Only slight rice phytotoxicity was observed at 5m and 2m from application point of U-Granule molinate+simetryn+imazosulfuron and molinate+imazosulfuron, respectively. So it is concluded that there is little phytotoxicity problem in practical application of U-Granule of molinate mixtures.

• Korean Journal of Weed Science
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• v.32 no.3
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• pp.280-284
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• 2012

No-tillage direct seeding of rice is consumed less labor and oil energy by no plowing and rotary tillage. And it has other advantages of soil and water conservation and accumulation of organic matter on paddy surface due to crowded water foxtail (Alopecurus aequalis var. amurensis). When no-tillage seeding of rice, many water foxtail occurred in winter paddy field. In this experiment their covering degrees were 97.6% and 95.2% in clay loam and sandy loam paddy soils, respectively. Because of this, Stellaria alsine var. undulata, Cardamine flexuosa, Rorippa indica and Ixeris chinensis etc. annual and perennial wintering weeds occurrence was reduced. And annual weeds Chenopodium serotinum and Polygonum hydropiper that occurred early in spring were also reduced. As well as Echinochloa crusgalli var. praticola, Cyperus difformis, Monochoria vaginalis and Lindernia procumbens etc. summer annual weeds that occurred after irrigation were also reduced. In conclusion, no-tillage direct seeding of rice has another advantages of weed management by water foxtail.

• Korean Journal of Weed Science
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• v.1 no.1
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• pp.52-56
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• 1981

A 2-year field experiment was conducted to determine the influence of early and late soybean (Clycine max Merr) seeding times on competitive relationships between soybeans and annual weeds. Soybeans were planted on May 20 and June 20. Durations of weed competition and weed control were 0, 3, 6, 9, and 12 weeks after planting sad for full growing season. Dominant weeds were Portulaca oleracia, Centipeda minima, Rorippa cantonienais, Chenopodium album, Acalypha australis, Echinochloa crusgalli, and Digitaria sanguinalis. The dry weight of weeds increased with extended competition, especially at early seeding time of soybeans. Soybean yields were decreased as duration of weed competition was extended. More severe yield reduction occurred at late-planted soybeans with early stage weed competition but at early-planted soybeans when weeds competed with soybeans for a 2 weeds and full growing season. The dry weight of weeds emerged after weeding was decreased at early and late seeding times of soybeans as duration of weed control was prolonged. Soybean yields decreased with shortening duration of weed control end this trend of yield reduction was slightly more remarkable at late-planted soybeans than at early-planted soybeans. Late-planted soybeans were required longer than 6 weeks of weed control period to achieve maximum yield as compared to early-planted soybeans.

• Korean Journal of Weed Science
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• v.4 no.2
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• pp.194-203
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• 1984

To evaluate the compatibility in systemic use of 4 kinds of herbicides on both weeds and soybeans, trials were conducted at Coll. Exp. Farm/Jonnam Nat'l. Univ., 1983. Among the experimented 4 herbicides, alachlor or metribuzin were applied at pre-emergence, and followed by postemergence spraying of acifluorfen or bentazon, respectively. All herbicides were applicated at rates of 0, 0.25, 0.5, and 0.75 kg active ingredients per ha. Under the conditions which Echinochloa crusgalli and Digitaria adscendense were dominating, most comprehensive compatibility was found from each rates 0.5 - 0.75 kg/ha at 60 days after crop seeding date. However, slight transient leaf burn was evident at the plots of metribuzin and/or acifluorfen applicated. The positive tendency of herbicide interactions in weeding efficacy was observed from the system in alachlor sequence. However, the results in crop growth and yields at hervest indicate the necessity of higher rates of each herbicides upto 0.75 kg/ha for the consistence weeding efficacies. And more excellent weeding results (crop growth and yields) on crop plants were provided from the plots which applicated by residual type herbicide, namely acifluorfen than bentzaon.

• Weed & Turfgrass Science
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• v.4 no.1
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• pp.1-9
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• 2015

Many irrigated and drainage canals, reservoirs, lakes, and rivers are choked by the explosive growth of aquatic weeds, resulting in enormous direct loss in Korea. Distribution of aquatic weeds and exotic invasive plant species in irrigation and drainage waterways, and riparian wetlands was reviewed to provide basic information for management of aquatic weeds and invasive plant species in wetlands. Dominant emergent weeds in canals, reservoirs and lakes were Phragmites communis, Leersia japonica, Zizania latifolia, Conyza canadensis, C. annuus, Rumex crispus, Panicum dichotomiflorum, Bidens frondosa, and Oenothera odorata. Dominant emergent weeds in wetlands of rivers include Digitaria sanguinalis, P. communis, R. crispus, Artemisia princeps, Humulus japonicus, Echinochloa crusgalli, B. frondosa, and Persicaria thunbergii. In irrigation and drainage canals and lakes, dominant submersed weeds were Hydrilla verticillata, Najas minor, Potamogeton malaianus, P. crispus, Ceratophyllum demersum, Myriophyllum verticillatum, Salvinia natans, and Trapa natans. Dominant exotic weeds in wetlands include Trifolium repens, O. odorata, C. annuus, B. frondosa, Avena fatua, Ambrosia artemisiifolia, X. strumarium, and P. dichotomiflorum. Approaches to aquatic weed control were mechanical, chemical and biological control techniques. Periodic monitoring of aquatic weeds and exotic weeds, and their integrated management studies are needed in waterways and riparian wetlands in Korea.

• Korean Journal of Weed Science
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• v.5 no.1
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• pp.19-23
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• 1985

Soil temperature was higher in clear or blue polyethylene film and bare soil than in black or green polyethylene film and straw mulching. Light transmission was low in black, blue or green colored polyethylene film and straw mulching. Germination of weeds was generally high under clear polyethylene film but black polyethylene film inhibited the germination. Germination of Portulaca oleracea, Setaria viridis and Amaranthus retroflexus increased under blue polyethylene film but inhibition of germination was observed in Erigeron canadensis, Avena fatua, Chenopodium ablum, Digitaria sanguinalis and Echinochloa crusgalli. Green polyethylene film mostly inhibited germination of weeds except A, fatua, C. album and E. canadensis. The greatest number of weeds emerged was obtained in clear polyethylene film, next in bare soil but green or blue polyethylene film inhibited the emergence of weeds. However, no emergence of weeds was observed under black polyethylene film. The highest dry weight of weeds was obtained in clear polyethylene film, next in bare soil, but green or blue polyethylene film and straw mulching caused suppression of weed growth. No weeds were grown under black polyethylene film.

• Korean Journal of Weed Science
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• v.2 no.1
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• pp.31-40
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• 1982

For the effective control of weeds in mechanically transplanted paddy field weeding effects of naproanide ${\alpha}$-(${\beta}$-naphthoxy) propion anilide], pyrazolate [4-2, 4-dichlorobenzoyl)-1, 3-dimethyl pyrazol-5-yl-p-tolune sulphanate], chlormethoxynil (2, 4-dichloro-phenyl-4-nitro-3-methoxy phenyl ether), SL-49 [1-3dimethyl-4(2, 4dichlorobenzoyl)-5-phenacyloxy pyrazole], ACN (3-chloro-2-amino-l, 4-naphthoquinone) either alone or in combination with butachlor (2-chlor-2, 6-diethyl-N-buthoxymethyl acetanilide) were compared. Pyrazolate and SL-49 were most effective for the control of Sagittaria pygmaea MIQ. and Potomogeton distinctus A. BENN. including most annual weeds. Weeding effect of butachlor alone was very high for annuals, good for Cyperus serotinus ROTTB. and poor for S. pygmaea and P. distinctus. But the weeding effect of the combination of butachlor and pyrazolate was stronger than that of butachlor alone and therefore this mixture was effective for S. pygmaea, P. distinctus and C. serotinus including all the annual weeds. The combination of butachlor and SL-49 showed the same tendency as the combination of butachlor and pyrazolate. Naproanilide was not effective for the control of Echinochlor crusgalli P. BEAUV and less effective for Monochoria vaginalis PRESL, but excellent for S. pygmaea. By mixing butachlor with naproanilide weeding, spectrum for annuals and S. pygmaea was much increased by that for P. distinctus and C. serotinus was not satisfactory. ACN was not satisfactory for the control of all the tested weeds but the weeding effect was increased in general by mixing with butachlor. Chlormethoxynil was excellent for the control of annual weeds but it has no effect on C. serotinus, S. pygmaea and P. distinctus showing some initial controling effect but these weeds regrew afterwards. The weeding activity of ACN increased in combination with butachlor and the residual activity was stronger than that of ACN alone. A light crop injury was found at the initial period after treatments in all treated plots. The yield from all treated plots except those from plots treated with ACN, butachlor and naproanilide were not significantly different from the band weeded plot.

• Korean Journal of Weed Science
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• v.15 no.4
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• pp.254-261
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• 1995

The nationwide weed survey was conducted in lowland rice fields over whole country of Korea in 1992 in order to determine a change of weed community and to identify a major dominant weed species and/or problem weed. Based on morphological characteristics of weeds, population ratio of broad leaf weed was 42.6%, grasses weed-9.0%, sedges-33.4% and others were 15.0%. Annual weed was 33.4% while perennial weed was 66.6% in terms of life cycle of weeds. Meanwhile, there was different weed occurrence as affected by planting method of the rice plant. In hand transplanted paddy fields predominant weed species was Sagittaria trifolia L., Monochoria vaginalis Presl., and Aneilema japonica Kunth. In machine transplanted rice fields of infant and young rice seedling Eleocharis kuroguwai Ohwi. and S. trifolia L. were more predominant. There was high occurrence of M. vaginalis, Echinochloa crus-galli L., and Leesia japonica Makino in water seeding while E. crus-galli and Cyperus serotinus Rottb. were predominant weed species in dry seeded rice. Monoculture of the rice plant would cause to high occurrence of E. kuroguwai, S. trifolia, M. vaginalis, E. crus-galli, and Sagittaria pygmaea Miq and there was higher population of S. trifolia, S. pygmaea, M. vaginalis, E crus-galli, and E. kuroguwai in double cropping system based on rice culture. In particular, there was high different weed occurrence under different transplanting times. E. kuroguwai, S. trifolia, S. pygmaea, M. vaginalis, and C. serotinus were higher population at the transplanting of 25 May and S. trifolia, E crus-galli, C. serotinus, and M. vaginalis at 10 June and S. pygmaea, E. kuroguwai, M. vaginalis, S. trifolia, and E. crusgalli at 25 June in Korea, respectively. Autumn tillage in terms of tillage time would cause more predominant weed species such as S. trifolia, E. kuroguwai, M. vaginalis, and S. pygmaea while spring tillage was higher population of E. kuroguwai, S. trifolia, E. crusgalli, M. vaginalis, and S. pygmaea. In plain area of paddy field there was higher occurrence of E. kuroguwai, S. trifolia, M. vaginalis, E. crus-galli, and S. pygmaea and in mid-mountainous area S. trifolia, E. kuroguwai, M. vaginalis, E. crus-galli, and Ludwigia prostrate Roxb. while in mountainous area S. trifolia, M. vaginalis, Potamogeton distinctus Ben., E. kuroguwai, and E. crus-galli were. In 1992 the most ten predominant weed species at the rice field of Korea based on summed dominant ratio(SDR) were E. kuroguwai > S. trifolia > E. crus-galli > M. vaginalis > S. pygmaea > C. serotinus > L. prostrate > P. distinctus > A. japonica > Scirpus juncoides Roxb.

• Korean Journal of Agricultural Science
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• v.4 no.2
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• pp.283-316
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• 1977

In an attempt to obtain a basic information to develop an effective integrated system of controlling sheath blight of rice in Korea, the transition of this disease, the variation of cultural characters and pathogenicity of the pathogen, environmental conditions affecting the disease outbreak and varietal resistance have been investigated. 1. Rice sheath blight which has been minor disease in the past was widely spread, especially since 1971. This disease has promptly spread all over the country and infected 65.2% of total rice growing area in 1976. Various factors are considered to be related to such transition of this disease. Above all, increace of application of nitrogenous fertilizer, early season and earlier cultivation of rice, introduction of more susceptible "Tongil" varieties etc. must be important factors influencing the outbreak of this disease. 2. Great variations in cultural characteristics-such as mycelial growth rate, color of the medium, amount of the aerial mycelium, shape and color of the sclerotia- and in the pathogenicity of isolates of the pathogen, Thanatephorus cucumeris Dank were observed. The optimum temperature for mycelial growth also varied with isolates, from $25^{\circ}C$ to $30^{\circ}C$. There were not necessarily any correlation between curtural characteristics and pathogenicity of isolates of Thanatephorus cucumens. 3. Mycelial grow th of isolates of Thanatephorus cucumens on the PDA medium were correlated with the air temperatures of the region where the isolates were collected. The isolates from the regions with high temperature grew well on PDA medium at $35^{\circ}C$ than those from the region with low temperature, on the other hand, the isolates from the regions with the low temperature grew well on the same medium at $12^{\circ}C$ than those from the regions with high temperature. 4. Pectin polygalacturonase (PG) and cellulase (Cx) were most active on the 3rd day after inoculation on the leaves of rice plant with Thanatephorus cucumeris, whereas pectin methylestrase (PE) was most active on the 4th day after inoculation. Relationship between the activities of PE of isolates and the strength of pathogenicity of isolates was obtained, but PG and cellulase activities were not correlated with pathogenicity of isolates. 5. The tolerence of sclerotia from in-vitro culture to low temperature varied with their water content, the dried cultural sclerotia were more tolerent than wet ones, Dried cultural sclerotia maintained almost 100% germinability for 45 days at $-20^{\circ}C$, whereas wet sclerotia lost viability at $-5^{\circ}C$. The germination ratio of the sclerotia after overwintering changed from 18% to 70% according to the water content of the test paddy fields and the ratio was low in wet paddy condition. 6. To investigate the host range of this fungi in and near paddy field, 17 weeds were inoculated with fungi. The lesions of sheath blight disease was obserbed on Sagittaria trifolia L., Echinochloa crusgalli P. Beauv., Monochoria vaginal is Presl, Polygonum Hydropiper L., Eclipta prostrata L., Digitaria sanguinalis Scapoli. 7. When the level of nitrogen applied was doubled over standard level, total nitrogen content in rice sheath increased, ami when silicate was applied, starch content in rice sheath decreased, inducing the rice plants more susceptible to sheath blight disease. Increased dressing of potash ferilizer reduced the incidence of sheat blight disease. 8. The percentage of infected stems in the early period increased more in the narrow hill plot than in the wide hill plot, but in the late period this tendency was inversed; the percentage of infected stems as well as severity in the wide hill plot increased more compared to the narrow hill plot, and the disease severity in the one plant per hill plot was also low. The number of stems in the wide hill plot was more than the number of stems in the narrow hill plot. This indicates that the microclimate, such as the relative humidity, in the narrow hill plot was more favorable for the development of this disease. 9. There was a high negative correlation between the disease severity of varieties to the sheath blight and the maturity of the varieties, that is, the early varieties were more susceptible than the late ones, and much-tillering varieties usually showed more infection than less tillering varieties. 10. No relationship was obtained between the percentage of infected stems in the early period and the severity after heading, whereas a distinct relationship was obtained between former and latter after Aug. 10.