• Korean Journal of Weed Science
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• v.31 no.2
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• pp.205-211
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• 2011

• 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.31 no.3
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• pp.221-228
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• 2011

Weed control is of fundamental importance when planting horticultural crops, particularly during the establishment phase. Weeds compete for nutrients, water and light, and can severely threaten the survival and early growth of newly planted crops. Failure to control weeds represents one of the single most important factors leading to crop loss. Knowledge on the existence of the diversity of weed species in greenhouses is of our main concern in this study in order to develop a most efficient and effective weed control strategies. Sixty-two greenhouses were surveyed in 3 cities and counties of Gyeongnam area in March to October 2009 to investigate the feature of weed occurrence in polyvinyl chloride (PVC) after harvesting of the main crops. Forty-one weed species were identified and classified to 18 families which were composed of 14 annual weeds, 18 summer annual weeds and 9 perennial weeds. On the other hand, broadleaf, grasses and sedges recorded with 30, 7 and 4 weed species, respectively. Asteraceae was the most dominant weed species (9 species) noted followed by Poaceae (7 species), Cyperaceae (4 species), Caryophyllaceae and Brassicaceae (3 species respectively) and other families have 1~2 species. The dominant weed species occurred in the greenhouse based on the summed dominance ratio. These weeds were Digitaria sanguinalis, Cyperus iria, Portulaca oleracea, Rorippa islandica, Mazus japonicas, Cardamine flexousa, and Eclipta prostrata and others. Weed occurrence in the greenhouse after horticultural crops consisted of summer annuals (4 species), winter annuals (3 species), and perennial annuals (1 specie). The dominant species occurred in tilled soil based on summed dominance ratio of weeds were Cardamine flexousa (88.1%), Eclipta prostrate (57.4%) and Portulaca oleracea (55.2%). Comparison of weed occurrence was thoroughly surveyed also in which field without PVC, weed species were Portulaca oleracea (55.2), Eclipta prostrata (57.9%) and Trigonotis peduncularis (25.1%) and field with PVC, the identified weeds were Portulaca oleracea (98.75), Trigonotis peduncularis (49.1%), and Eclipta prostrata (36.8%).

• Korean Journal of Organic Agriculture
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• v.17 no.4
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• pp.501-517
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• 2009

This research was carried out to study the effect of mulching materials and weed control methods on weed occurrence and growth of kale on upland and paddy soil of field culture at spring and autumn season. Paddy soil temperature of mulching treatments was high by $0.9{\sim}2.0^{\circ}C$ in comparison of non-mulching at autumn season. The control value of weed was over 91% at mulch paper and time required for weed control was reduced by 70% at mulch paper + machine weeding in comparison of non-mulching + hand weeding. The yield of kale was similar to that of conventional culture. Paddy soil temperature of mulch paper was higher on April, but lower on May and June than non-mulching at spring season. Dominant weed was Chenopodium album var. centrorubrum Makino, The control value of weed was over 91% at mulch paper, time required for weed control was reduced by 75% at mulch paper + machine weeding in comparison of non-mulching + hand weeding and the yield of kale increased by 34% than conventional culture. Dominant weed was Alopecurus aequalis var. amurensis Ohwi. on paddy soil at autumn season. The control value of weed was 43% at mulch paper. Time required for weed control was reduced by 80% at mulch paper + machine weeding in comparison of non-mulching + hand weeding. The yield of kale increased by 26% compared with than of conventional culture.

• Korean Journal of Medicinal Crop Science
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• v.6 no.1
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• pp.44-50
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• 1998

The experiment was carried out to investigate weed occurrence in peony field. The number of weeds was Compositate 9 species, Gramineae 4 species, Craciferae 3 species, Eugarviaceae, Polygonaceae and Scrophularilaceae 2 species, respectively. Weeds classified by life cycle were annual weed 19 species (57.6%), biennial weed 8 species (24.2%), and perennial weed 6 species (18.2%). Weed species and dominance rate by morphological characteristics were grass weed 4 species (12.1%), broad leaf weed 25 species (84.8%), and sedge weed 1 species (3.1 %) . Major dominant weeds were Capsella bursa-pastoris, Chemopodium album var. centrorubrum and Equisetum arvense in late April, and Digitaria sanguinalis, Erigeron canadensis and Echinochlor crus-galli in late June, and Digitaria sanguinalis, Erigeron canadensis and Echinochlor crus-galli in middle August.

• Korean Journal of Soil Science and Fertilizer
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• v.18 no.3
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• pp.304-311
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• 1985

This study was carried out to find the spring-season weed growth status on account of different soil physicochemical properties due to continuous application of same fertilizer for 8 years at paddy field. The results examined on weed species, dry weight of weed, and weed growth status were summarized as follows. 1. 1-6 species of weed occurred in the plots treated by continueous application of different fertilizers. Cyperus serotinus could grow only in the phosphate defficient plots, however, in the N+P+K, N+P and N+P+K+compost plots, 4-6 kinds of weed occurred variously. 2. In the plots applied phosphate like as, P, P+K, N+P+K+compost, and N+P+K+plots, large amount of weed occurred apparently. 3. Positive correlation betwaen dry weight of Alopeculus aequalis, polygonum hydropiper and Chenopodium alburn and available phosphate content in soil was showed with high significance. 4. Available phosphate in soil affected weed growth and weed species composition among weed communities. Application of lime fertilizer tended to suppress the occurrence of Alopeculus aequalis. 5. Dry matter of polygonum Longisetum, Chenopodium album and polygonum hydropiper showed higher content of nitrogen, phosphate, calcium, and magnesium. Whereas those of Alopeculus aequalis, Cyperus Serotinus and Stellaria alsine were less.

• Weed & Turfgrass Science
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• v.2 no.2
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• pp.131-137
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• 2013

The study was carried out to obtain the basic information on distribution and occurrence of weeds including resistant weeds to sulfonylurea herbicides in paddy fields of Gyeongbuk province. In weed distribution on life cycle, annual weed was occupied by 91.8% and perennials were 8.2%, respectively. In morphological distribution of weeds, broad leaf weeds were 85.7%, sedges was 9.1%, and grass weed was 3.8%, respectively. Sulfonylurea-resistant weeds in paddy fields of twelve regions were widely occurred except for Yecheon region. The six sulfonylurea resistant biotypes occurred in paddy fields of Gyeongbuk province were Lindernia dubia, Eleocharis kuroguwai, Monochoria vaginalis and Ludwigia prostrata. It revealed that occurrence rate and area of sulfonylurea-resistant weeds were about 15.9 % and 22,420 ha in Gyeongbuk province.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.4 no.1
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• pp.16-23
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• 2001

This study was conducted to analyse the relation between physical characteristics of soil surface and wild plants occurrence. Lots of natural occurrence on loamy soil and a little of natural occurrence on perlite. Those were used to observe the wild plants occurrence through the duration. Natural occurrence of wild plants were observed on uniform sand, perlite, loamy soil and 2cms loamy soil layer above the perlite. Uniform sand was compared with different height of drain ditch. The results of analysis were as followed. 1. Wild plants germinated on the uniform perlite layer, they did not grow larger. Because water in large pores of perlite surface drained rapidly and evaporated easily, therefore surface remained low moisture contents. 2. A lot of weed grew on 2cms loamy layer on perlite which stratified above the perlite layer. Because perlite had plenty of soil moisture and soil moisture moved easily from perlite to loamy soil layer. 3. Uniform loamy soil had similar occurrence on the uniform perlite. It was nearly same at surface moisture distribution but lower than layered loamy soil on perlite, and the vertical distributions at soil moisture was totally lower than 2cms loamy soil layer on perlite. 4. Wild plants were grew on uniform sand on different height of drain ditch. In this case, much more wild plants were grew on which had more higher drainage ditch. The number of wild plants occurred when it was affected by soil surface moisture, drain ditch and natural occurrence of wild plants. This could be controlled by layered soil at surface moisture. Therefore weed occurrence can control in planting ground, where soil layer would not be disturbed.

• Korean Journal of Weed Science
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• v.31 no.1
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• pp.89-95
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• 2011

In present study we focused on the weed occurrence and diversity in rice field according to methods of weed control. Experiments comprised of no herbicide treatment (NHT), herbicide treatment (HT) and golden apple snail treatment (GAST) within the three months (July to September) of growing rice. According to results, five to seven different weed species were found in NHT, while two to four different weed species were found in HT and GAST. Monochoria vaginalis was dominant species during growing period in NHT and HT while Lemna paucicostata was the dominant in July but Persicaria hydropiper was dominant for August and September. Simpson's dominance index was highest in GAST(0.96) compared with other treatments (NHT 0.27 and HT : 0.51). The similarity coefficient was 50.31%, 4.65% and 0.38% for NHT versus HT, NHT versus GAST and HT versus GAST, respectively. In conclusion, the weed species diversity, dominance and similarity coefficient were varied in different weed control methods of rice growing.

• Research in Plant Disease
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• v.12 no.3
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• pp.158-163
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• 2006

Sclerotinia rot caused by Sclerotinia sclerotiorum frequently causes serious and unpredicable yield losses of the leaves of perilla growing under structured cultivation as vegetable in Korea. Temperature for mycelial growth ranged from 5 to $30^{\circ}C$ with optimum temperature d $20^{\circ}C$. Sclerotia were formed fewer at low temperature, but their dry weight was heavier than that at high temperature. The apothecia were formed from the sclerotia that buried up to 3 cm soil depth at $15^{\circ}C$ in moisture condition. The incidence of perilla Sclerotinia rot caused by S. sclerotiorum was observed throughout the growing season at greenhouse. The occurrence of this disease was especially severe from January to February of low temperature period. The average incidence rates of this disease was up to 15%. The significant occurrence of this disease was showed mainly in the continuous cropping field for more than five years. The incidence of this disease increased according to the increase of continuous cropping year. The incidence rates of this disease reached up to 20% in the continuous cropping field for ten years. Also it was firstly investigated the natural infection caused by S. sclerotiorum on weed plants, Gnaphalium affine and Mazus pumilus in farmer's field. The casual fungus showed pathogenicity on 11 weed plants species tested, and more severe pathogenicity on G. affine, Latuca indica and Ixeris dentata included in the family Compositae. This result suggests that effective crop rotation and weed eradication can be the method for organic control of perilla sclerotinia rot, and sudden outbreaks of this disease on perilla growing under structure after paddy rice call be explained by the presence of weed hosts.