• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.2
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• pp.159-164
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• 2019

Weed control is a crucial practice not only in organic farming, but also in modern agriculture because it can lead to loss in crop yield. In general, weed is distributed in patches heterogeneously in the field. These patches vary in size, shape, and density. Thus, it would be efficient if chemicals are sprayed on these patches rather than spraying uniformly in the field, which can pollute the environment and be cost prohibitive. In this sense, weed detection could be beneficial for sustainable agriculture. Studies have been conducted to detect weed patches in the field using remote sensing technologies, which can be classified into a method using image segmentation based on morphology and a method with vegetative indices based on the wavelength of light. In this study, the latter methodology has been used to detect the weed patches. As a result, it was found that the vegetative indices were easier to operate as it did not need any sophisticated algorithm for differentiating weeds from crop and soil as compared to the former method. Consequently, we demonstrated that the current method of using vegetative index is accurate enough to detect weed patches, and will be useful for farmers to control weeds with minimal use of chemicals and in a more precise manner.

• Korean Journal of Plant Resources
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• v.23 no.3
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• pp.242-247
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• 2010

This study was carried out to elucidate the effect of mulching materials on the growth of Chinese chive (Allium tuberusum Rottler) and weed control. Chinese chive was grown under five mulching materials, pine leaf, oak leaf, rice straw, rice hull and sawdust, at the Experimental Farm of Chungbuk National University from June 20, 2009 to September 30, 2009. Amaranthus mangostunus, Digitaria sanguinalis, Portuclaca. oleracea, Echinochioa crus-galli var. frumetacea and Setaria viridis were dominant weeds. Both pine and oak leaves were significantly effective mulching materials in terms of weed control indices in both nursery and field. Soil moisture contents were 1.2~3.7% higher in mulching, especially in oak leaf mulching. Mulching with pine leaf significantly increased plant height, sheath length, leaf length, bulb-, root- and leaf-weights and yield of Chinese chive, but there were no significant differences among the other mulching materials although better than those in non-mulching.

• Korean Journal of Weed Science
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• v.1 no.1
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• pp.78-83
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• 1981

This study was attempted to determine the major weed species occurring in Korean turfgrass, Zoysia japonica Steud. and to evaluate the most effective means for controlling them. More or less 40 weed species were determined to occur in Korean turfgrass. In terms of quantity and frequency of occurrence, Trifolium repens L., Digitaria sanguinalis (L.) Scop., Draba nemorosa var. hebecarpa Lindbl, Erigeron canadensis L., and Cyperus amuricus Max were observed to be the major weeds. Simpson's index, 0.306 was obtained to be the major weeds. Simpson's index, 0.306 was obtained in the golf course, Jinryang, Gyungsan-gun, meaning that no specific weed species were dominant, but in Kyungpook National University campus, Trifolium repense L. was a single dominant species, indicating Simpson's index, 0.776. The most effective herbicides to control Trifolium repense L. and other broad leaf weeds were MCPP [2-(2-methyl-4-chlorophenoxy) propionic acid), followed by 2,4-D (2,4-dichlolophenoxy acetic acid). Increased rates of both herbicides increased markedly their effectivity against weeds, with very slight injury against turfgrass. MCPP at 2.8 kg(a.i.)/ha gave excellent control without any injury and 2,4-D at 1.0 kg(a.i.)/ha.

• Spatial Information Research
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• v.3 no.1
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• pp.47-53
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• 1995

The weed survey in lowland rice fields through Korea was conducted in 1992 to determine a change of the weed communities based on different regions, soil types, planting methods, and cultural practices. GIS was applied to identify a spatial analysis of predominant weed species in specific region. On behalf of vegetatine analysis such as absolute and relative density, absolute and relative frequency, importance value, and summed dominance ratio(SDR), there was highly dominant with a perennial weed species, Eleocharis kuroguwai Ohwi over whole country. However, in particular it was most predominant at southem area of Gyunggi province in Korea. Thus, rice farmers of this area have to introduce a specific comperhensive control strategy against this predominant weed species.

• 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.

• Korean Journal of Organic Agriculture
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• v.20 no.2
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• pp.201-209
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• 2012

This study was conducted to evaluate the effects of crop rotation on the weed occurrence in green onion and red pepper cultivation. Rye and hairy vetch were annually seeded for winter season. The reduction of weed germination was pronounced by about 50% in green onion field, but was not significant in red pepper field through rye cropping. Among weed species, the germination of Abutilon theophrasti, Cyperus iria and Digitaria ciliaris was distinctly inhibited by exudate of rye root, but not by that of hairy vetch in vitro experiment. The return of rye biomass into onion field decreased amount of weed biomass but increased index of weed diversity.

• Korean Journal of Weed Science
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• v.11 no.3
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• pp.178-186
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• 1991

This study was conducted to evaluate the major weeds occurred in direct seeded rice and their compition with rice, and to establish the effective weed control method. The important weeds occurring in dry direct seeded rice were Echinochloa crusgalli, Cyperus amuricus, Rorippa islandica, etc. Among them, Echinochloa crusgalli was the most dominant weed species. In view of the Simpson's dominance index, the maximum number of the weeds was observed at 30 days after seeding, showing 0.26, but decreased as the time passed. In other hand, Simpson's dominance index of weed dry weight increased from 0.09 at 15DAS(days after seeding) to 0.28 at 60DAS indicating that particular weed such as barnyardgrass was dominating the fields. The plant height and the tiller number of rice in the dry direct seeded rice were not greatly affected by the time and duration of competition with weeds, but rice yield was greatly influenced by them. The yield reduction was observed when compition between rice and weeds were initiated at 20 to 40 DAS till the harvesting time. The highest weed control efficacy was observed at the treatment of systematic herbicide application such as soil applied Butachlor followed by Mefenacet/Bensulfuron-methyl/Dymron at 30 DAS after seeding, and soil applied Dimepiperate/Bensulfuron-methyl mixture as a preemergence type gave also an excellent control.

• Korean Journal of Weed Science
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• v.8 no.1
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• pp.1-8
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• 1988

In order to get basic information for establishing weed control methods, weed distribution was surveyed at 15 days interval in garlic and red pepper fields at 8 locations in Chungnam Province. In garlic fields, 68 weed species(27 families) were distributed. Portulaca oleracea, Chenopodium album and Digitana sanguinalis were most dominant and Equisetum arvense, Alopecurus aequalis, and Setaria viridis dominant among them. Highest number of weeds emerged in May and dry weight or weeds was more heavy in June and summer broadleaf weeds were most abundant throughout garlic growing period. In red pepper fields, 38 weed species(17 families) were distributed, D. sanguinalis, Cyperus amuricus and P. oleracea were most dominant and Echinochloa crus-galli, Eleusine indica, D. violascens, and Centipeda minima also dominant among them. The highest number of weeds were emerged in June and summer, grasses and summer broadleaf weeds were more abundant in June and July. Seasonal Shannon's diversity index(H'), maximum diversity(Hmax') and eveness(J') for the Shannon diversity index, and Simpson index were high in both red pepper and garlic fields. Interspecific competition(probability for interspecific encounter) was more severe than intraspecific competiton.

• 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.

• Korean Journal of Weed Science
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• v.17 no.2
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• pp.139-146
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• 1997

The experiment was conducted at Gyeongbuk Provincial Rural Development Administration in 1996 to obtain basic information on weed ecology and effective weed control in direct-seeded rice fields under different seeding types and seeding times. A large number of upland weeds such as Echinochloa crus-galli, Digitaria sanguinalis, Capsella bursa-pastoris and Stetaria viridis etc occurred at early growth stage, while Eleocharis kuroguwai, Aneilema keisak and Cyperus serotinus dominated at late stage in dry seeded rice field. In wet seeded rice field, the dominance of E. crus-galli was lower and the occurrence of M. vaginalis and A. keisak were higher than in dry seeded field. Amount of weed occurrence in dry seeded field was 1.8 to 2.4 times greater than in wet seeded field and it increased with delaying seeding time. Increasing rate of weed occurrence through whole life cycle was the highest at 20 days after seeding (DAS) to 40 DAS, regardless of seeding types and seeding times. Simpson index in wet seeded field was higher than in dry seeded field and it gradually increased as growing of dominant species. For F-value test, it was recognized as statistical significant in seeding types, seeding times and interaction of two factors.