• Weed & Turfgrass Science
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• v.3 no.2
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• pp.86-94
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• 2014

Survey was carried out in paddy fields to investigate the dominance of weed species and weed occurrence on 200 fields of southern Gyeonggi region in Korea during the year 2013. We observed 3 species of grass, 5 species of sedge, and 11 species of broadleaf and other weeds. The most dominant weed species was Eleocharis kuroguwai, followed by Echinochloa crus-galli, Sagittaria trifolia, Monochoria vaginalis, Scirpus juncoides and Bidens tripartita. The dominance value of E. kuroguwai and B. tripartita decreased compared to the survey results performed in 2005 but that of M. vaginalis, S. juncoides, S. trifolia and E. crus-galli increased. Weed occurrence increased from 2.83 g in 2005 to 3.51 g in 2013 based on weed dry weight per $m^2$. Occurrence ratio of annual weeds to perennial weeds changed from 45.2% : 54.8% in 2005 to 45.8% : 54.2% in 2013. If we analyze dominance of weed species based on the rice transplanting timing, E. kuroguwai and E. crus-galli were the most dominant weed species at mid-May transplanting, and M. vaginalis and S. juncoides were the most dominant weed species at late- May transplanting, and M. vaginalis and E. kuroguwai were the most dominant weed species at early-June transplanting. Since paddy weeds resistant to sulfonylurea herbicides are expected to be continuously increased, the regular monitoring of their occurrence and efficient control methods should be considered in future.

• Korean Journal of Weed Science
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• v.30 no.2
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• pp.68-83
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• 2010

Weedy rice (Oryza sativa L.) occurred sympatrically with other weeds and the rice crop in Malaysian rice granaries. We conducted field surveys in 2006-2008 seasons in 7 farm blocks of Selangor's North West Project, Malaysia to enlist the new biotypes of weedy rice (NBWR) and assess their spatio-temporal pattern of distribution based on quantitative and dispersion indices. No less than 16 accessions of NBWR were identified based on their special traits, viz. panicle type, pericarp colour, presence or absence of awn, seed type and degree of grain shattering. The NBWR accessions exhibited a combination of morphological traits from open panicle, grain with awns, red pericarp, short grain type, and degrees of grain shattering. Others mimic commercial rices with close panicle, awnless grains, white pericarp, long or short grain-type. Invariably, the NBWRs mimic and stand as tall as cultivated rice namely MR219, MR220, or MR235 and these NBWR accessions stand among equals morphologically vis-a-vis the commercial rice varieties. Most accessions displayed varying degrees of grain shattering in excess of 50%, except Acc9 and Acc12. The seasonal dynamics of on the prevalence of dominant NBWR accessions were also displaying significant differences among farm blocks. While Bagan Terap farm block, for example, did not record any measurable changes in the dominant NBWR accessions over seasons, the Sungai Leman farm block recorded measurable season-mediated changes in the dominant NBWR accessions. Sungai Leman started with NBWR Acc3, Acc4, Acc5, Acc7, Acc8, and Acc12 in season 1 of 2006/2007, but no measurable records of Acc3 and Acc5 were shown in season 2 of 2007. In season 3 of 2007/2008, only Acc8 and Acc12 prevailed in the farm block. In Sawah Sempadan farm block, season 3 of 2007/2008 showed much reduced prevalence of NBWRs leaving only Acc8 and Acc12. Most accessions registered clump or under-dispersed spatial distribution pattern based on quantitative indices: variance-to-mean ratio (VMR) and Lloyd's patchiness values. The dynamics on the extent of infestation and prevalence of dominant NBWR accessions registered both season- and farm-block mediated differences. Most accessions showed VMR >1 thus indicative of having a clump or clustered spatial distribution, as exemplified by Acc3, Acc4, Acc7, Acc8 and Acc12 in all farm blocks throughout three seasons. Some accessions have either random or uniform distribution in a few farm blocks. The Acc8 has the highest population counts based on important value index, followed by Acc12, and both were the most dominant accession while Sawah Sempadan was the worst farm block infested by NBWR compared to other farm blocks. These results were discussed in relation with the current agronomic and weed management practices, water availability and extension services in the granary.

• Weed & Turfgrass Science
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• v.4 no.2
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• pp.77-84
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• 2015

We surveyed the distribution pattern of weeds in onion, garlic, potato, and barley fields including 304 sites of Gyeongsangbuk-do. The weeds were summarized as 30 family and 125 species in onion crop field, 29 family and 101 species in garlic field, 30 family 88 species in potato field, finally 27 family and 108 species. Compositae was dominant family (26.4%, 33 species), followed by Polygonaceae (8.8%, 11 species), Cruciferae (8.8%, 11 species) in onion field. Compositae was also dominant family (24.8%, 25 species) in garlic field, it was 22.7% (20 species) in potato field, and it was also 24.1% (26 species) in barley field, respectively. Among these winter crops, major five families were occupied 61.1, 58.4, 58.0 and 57.5% in turn at barley, onion, potato and garlic fields. The PCA-covariance plot analysis for investigation of occurrence pattern of weeds by four winter crop fields revealed that the occurrence pattern of weed species in barley field was distinguished by Alopecurus aequalis var. amurensis, Stellaria alsine var. undulate and Stellaria aquatica.

• Korean Journal of Weed Science
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• v.17 no.1
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• pp.1-9
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• 1997

The survey of weed community in paddy field was carried out to investigate the changes of weed species on 340 fields in Kyonggi Area in 1995, that is almost same condition as sampled in 1991. The weed species observed include 3 species of grasses, 5 species of sedges and 14 species of broadleaf and other weed. Herbicide treatment system in one time treatment vs more than two time treatment was 34:66 percentage. About 25 percentage among one time treatment system was used butachlor G. Ratio of annual weed vs perennial weed was 38:62, and then perennial weed ratio was high. Major dominant weed species were Sagitaria trifolia, Eleocharis kuroguwai, Echinochloa crus-galli, Bidens tripartita and Monochoria vaginalis. Weed occurrence was decreased as order of normal soil, poorly drained soil and saline soil. Dormant weed species were S. trifolia, E. kuroguwai, E. crus-galli and B. tripartita in normal soil and were S. trifolia, E. kuroguwai, E. crus-galli and Polygonium hydropiper in poorly drained soil, and were Scirpus planiculmis, S. trifolia and E. kuroguwai in saline soil. Weed occurrence was increased with delaying the transplanting time; dominant weed species were S. trifolia, E. kuroguwai, E. crus-galli and M. vaginalis in May transplanting field and were E. kuroguwai, S. trifolia, and C. serotinus in June transplanting field. Weed occurrence was decreased as order of non-plowing transplanting field, autumn plowing and spring plowing paddy field. Dominant weed species were S. trifolia, E. kuroguwai, E. crus-galli and M. vaginalis in autumn plowing, were S. trifolia, E. kuroguwai, E. crus-galli and B. tripartita in spring plowing, and were E. crus-galli, S. hotarui and S. trifolia in non-plowing transplanting field.

• Weed & Turfgrass Science
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• v.6 no.2
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• pp.117-123
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• 2017

Invasive alien species (IAS) can affect agricultural ecosystem negatively and critically. The geographical distributions of nine IAS plants in Korean orchards and uplands were investigated. Ambrosia artemisiifolia distributed widely in Korean peninsula and Ambrosia trifida distributed intensively in Gyeonggi-do. Aster pilosus distributed in Gyeonggi-Gangwon region and Lactuca scariola distributed linear region from the north-western to south-eastern part of Korea. Hypochaeris radicata distributed mainly in Jeju-do and Solanum carolinense distributed in eastern Gyeonggi-do. Rumex acetosella and Sicyos angulatus sporadically occurred in Korean croplands and Eupatorium rugosum was found in one region only. The distribution of IAS plants in croplands was very similar to that in non-croplands suggesting that ecological position of arable lands is not different from that of non-arable lands. Therefore, IAS plants in the croplands should be managed for not only prevention of yield reduction, but also protection or maintenance of original ecosystem. Development of management methods apposite to current Korean status are required to control IAS plants in croplands.

• 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.

• Journal of The Korean Society of Grassland and Forage Science
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• v.21 no.2
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• pp.97-102
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• 2001

This study was carried out to survey the weed distributions in 6 areas(Suwon, Seonghwan, Seosan, Taekwanryeong, Namwon and Yeongam) and to investigate the ecological characteristics of exotic weeds from 1997 to 1999. Total 44 species in 15 families of exotic weds were observed in grassland and forage crop field. Among them 4 species in 1 family were monocotyledonous and 40 species in 14 families were dicotyledonous weeds. Most common species among exotic weeds examined in this study were Rumex acetosella, Rumex crispus. Chenopodium album, Abutilon theophrasti, Amaranthus retroflexus, Polygonum orientale etc. Inedible weeds with hairs, prickles, fetor or poison were Solanum carolinense Xanthium strumarium, Datura stramnium, Erechtites hieracifolia, Anthemis cotula, Phytolaca americana etc. The relative density of Phytolaca americana increased with decreament of soil pH and content of available phosphate, and that of Solanum carolinense increased with decreament of soil pH and increament of available phosphate. Most of exotic weed seeds germinated well under light condition with $25~30^{\circ}C$, and some of those were hard or dormant seed.

• Korean Journal of Weed Science
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• v.8 no.2
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• pp.164-168
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• 1988

In order to get basic information for establishing weed control methods in apple orchards, weed distribution was surveyed at 2 locations in Chungnam Province at 15 days intervals. In apple orchard 48 weed species (18 families) were distributed and Chenopodium album and Polygonum hydropiper were dominated and Digitana sanguinalis, Portulaca oleracea, and Erigeron canadensis were also abundant among them. Highest number of weeds emerged in April and dry weight of weeds were heavy in June and October, especially in summer broadleaf weeds and winter broadleaf weeds, and winter grasses were abundant in spring. Seasonal Shannon's diversity index(H'), maximum diversity(H max'), eveness (J') for the Shannon diversity index, and Simpson index were high in apple orchards. Interspecific competition was more severe than intraspecific competition.

• Proceedings of the Korean Society of Crop Science Conference
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• 1991.05a
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• pp.84-85
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• 1991

• Korean Journal of Weed Science
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• v.9 no.2
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• pp.130-140
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• 1989

1) Dormancy brocken weed seeds were planted in soil at 15 days interval from June to December in 1986 and 1987 and test of normality and normal distribution curve were made to determine seasonal distribution characteristics of weed emergence in fields. Monthly emergence distribution pattern of each species can be concluded as following normal distribution equations. E. crusgalli $y={\frac{1}{2.52{\sqrt{2{\pi}}}}}e^{-{\frac{(x-10.057)^2}{12.7}}}$ E. indica $y={\frac{1}{2.17{\sqrt{2{\pi}}}}}e^{-{\frac{(x-9.16)^2}{9.45}}}$ A. lividus $y={\frac{1}{7.74{\sqrt{2{\pi}}}}}e^{-{\frac{(x-10.06)^2}{15.46}}}$ S. nigrum $y={\frac{1}{2.7{\sqrt{2{\pi}}}}}e^{-{\frac{(x-9.695)^2}{14.58}}}$ C. busrsa-pastoris $y={\frac{1}{2.83{\sqrt{2{\pi}}}}}e^{-{\frac{(x-9.02)^2}{16.02}}}$ D. sanguinalis $y={\frac{1}{2.8{\sqrt{2{\pi}}}}}e^{-{\frac{(x-8.58)^2}{15.67}}}$ S. viridis $y={\frac{1}{2.72{\sqrt{2{\pi}}}}}e^{-{\frac{(x-9.36)^2}{14.8}}}$ C. album $y={\frac{1}{2.596{\sqrt{2{\pi}}}}}e^{-{\frac{(x-8.07)^2}{13.48}}}$ P. oleraeda $y={\frac{1}{2.45{\sqrt{2{\pi}}}}}e^{-{\frac{(x-10.83)^2}{12.01}}}$ 2) Emergence peak period of weed species tested were from the end of May to early August and yearly variation of emergence was observed in E. crus-galli, S. viridis, S, nigrum, and P. oleracea and this fact may more related to rainfall pattern rather than temperature.