• Weed & Turfgrass Science
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• v.3 no.2
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• pp.78-85
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• 2014

The survey of weed occurrence was conducted to identify dominant weed species in the paddy field. Total 346 sites of the 12 regions in Chungbuk Province in Korea were investigated in July, 2013. Weed flora was composed of 43 species belonged to 15 families. The compositions of major plant families, Cyperaces, Poaceae, Pontederiaceae and Asteraceae, were 21.5, 17.4, 15.5 and 12.7%, respectively. Based on life cycle, weed species was grouped into annuals of 71.3 and perennials of 28.1%. The most dominant weed species in paddy fields of Chungbuk Province were Monochoria vaginalis (14.5%), followed by Scirpus juncoides (10.5%), Echinochloa oryzoides (9.3%), Eleocharis kuroguwai (7.0%), Aeschynomene indica (6.2%) et al. The similarity of paddy weeds in 12 regions observed through TWINSPAN analysis was distinguished by Persicaria longiseta, Aneilema keisak, Persicaria thunbergii, Fimbristylis millacea, Blyxa japonica, Digitaria ciliaris, Potamogeton distinctus, Cyperus nipponicus. This information could be useful for estimation of future weed occurrence and establishment of weed control methods in chungbuk province in Korea.

• Weed & Turfgrass Science
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• v.2 no.4
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• pp.341-347
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• 2013

The survey of weed occurrence was conducted to identify problematic weed species on the paddy field. Total 524 sites of the 17 regions in Chungnam Province in Korea were investigated from June to August, 2013. In the whole region, 23 weed species were identified including 19 annuals and 4 perennials. The most dominant weed species in Chungnam paddy fields were Echinochloa crus-galli (25.3%), followed by Monochoria vaginalis (11.9%), Eleocharis kuroguwai (10.3%), Bidens tripartite (9.3%) and Aneilema japonicum (8.5%). The 95.2% of the investigation sites was determined under dominance value 1 (range of cover <10: numerous individuals) by Braun-Branquet indicating proper weed control in the paddy fields. This information could be useful for estimation of future weed occurrence, weed population dynamics and establishment of weed control methods in Chungnam Province in Korea.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.2
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• pp.69-76
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• 2006

Fallow paddy areas have been increased due to the import of cheap agricultural product, and the unbalance between farming cost and rice price since 1990. The increasing fallow paddy area needs to be protected from the devastation by weed breeding for the re-cultivation. In this study, two fallow paddy fields managed with different water depth were selected for monitoring and analysing of water quality, water balance and plant body change. The managed fallow paddy fields were more effective in water quality purification and plants growth control than non-managed fallow paddy fields. And the fallow paddy field managed with some degree of water depth was the most effective field in terms of weed control.

• Korean Journal of Weed Science
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• v.15 no.4
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• pp.305-312
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• 1995

Weed communities in the dry-direct seeded rice(Oryza sativa L.), soybean(Glycine max(L.) Merr.), and dry-direct seeded rice-soybean rotation system from the transplanted rice field were investigated in order to identify a change in weed species by paddy-upland rotation. Echinochloa species was the most dominant species in the dry-direct seeded rice and their great increase was observed in the continued practices of dry-direct seeded rice. Echinochloa spp., Chenopodium ficifolium, and Digitaria spp. were identified as the major weeds in soybean cultivation in paddy field. Practice of soybean rotation in the dry-seeded rice reduced weed occurrence, particularly at the soybean after 2-yr continued dry-direct seeded rice and at dry-direct seeded rice culture after 2-yr continued dry-direct seeded rice and at dry-direct seeded rice culture after 2-yr soybean compared to the continued cultures of rice or soybean. In addition, cultivation of dry-direct seeded rice or soybean culture in the paddy rice field seemed to be helpful for suppression of perennial weeds(Eleocharis kuroguwai, Cyperus serotinus, Scirpus juncoides) and aquatic weeds(Monochoria vaginalis, Sagittaria spp. Potamogeton distinctus).

• Korean Journal of Weed Science
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• v.3 no.2
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• pp.246-251
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• 1983

In recent years weed flora have been changed to perennial dominance in paddy field being affected by the cropping systems and cultural practices. The perennial weeds are difficult to be controlled with annual herbicides which occupy 94% of total consumption of herbicides. The weeds competed more with rice plants in early tillering stages in machine transplanted field. For the reasonable and effective weed control, it is advisable to use single ai herbicides in hand transplanting field, but combined and mixed herbicides should be applied in machine transplanting field.

• Weed & Turfgrass Science
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• v.2 no.4
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• pp.358-361
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• 2013

This study was conducted to determine the weed control effect of false seedbed in organic rice paddy field. False seedbed is one of the preventative weed control method, especially effective in upland vegetable field. False seedbed frequency and methods were examined by varying the processing time in greenhouse and field condition in 2012 and 2013. In greenhouse experiment, shallow recultivation and harrow surface soil was effective to control weed up to 70%. Optimal processing time of false seedbed was when the weed was two or three leaf stages. Under field condition, one-time treatment of false seedbed was 61% of weed suppression rate and two-times of false seedbed treatment was 79% of weed suppression rate. Monochoria vaginalis was still troublesome weed after false seedbed treatment, but the occurrence of Echinochloa oryzoides was decreased after false seedbed treament. Results indicated that false seedbed treatment was very effective to lower early weed occurrence in rice paddy field especially Echinochloa spp. Weed control efficiency of shallow recultivation by weeder hollow and rotary tillage by tractor were 68%, 13% respectively.

• 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 Weed Science
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• v.15 no.4
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• pp.313-320
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• 1995

The major weeds observed in soybean(Glycine max(L.) Merr.) culture at the paddy field where transplanted rice was cultivated in previous year were Digitaria spp., Echinochloa spp., Chenopodium ficifolium, Rorippa islandica and Stellaria alsine. C. ficifolium and R. islandica increased as soybean was cultivated for two years in the same field. Weed biomass decreased by 84.8% as the seeding date was delayed from April 26 to May 20. Most of weeds started to emerge from 20 days after seeding(DAS) until 40 DAS, and higher seed yield was obtained by eliminating the weeds emerged until 40 DAS. The development of soybean branches, pods stem diameter was severely injured by weed interference, and thus soybean seed yield was reduced by 70% in comparison with a full season weed free plot. Herbicides such as pendimethalin, metolachlor, metolachlor+prometryn and alachlor controlled very effectively weeds present in soybean culture in rice-soybean rotated paddy field.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.485-489
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• 2005

Fallow paddy has been increased in disadvantageous farming condition area because of importation of foreign agricultural products, labor cost and the imbalance between farming cost and agricultural products price since 1990. The fallow paddy that has gradually increased needs to be prevented from the devastation by weed breeding for re-cultivation. In this study, two fallow paddies that manage with different water depth from the experimental field were selected for observation, and analysis of water quality, water balance and plant body change. The managed fallow paddy was more effective in water quality purification and plants growth control than non-managed fallow paddy. And the fallow paddy managed with a some degree water depth was the most effective field on weed control.

• Korean Journal of Weed Science
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• v.8 no.2
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• pp.103-113
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• 1988