• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.23 no.2
• /
• pp.150-153
• /
• 1978

A study was conducted to determine the critical period of weed-free maintenance required to produce maximum soybean yields. Leaf area index(LAI). crop growth rate (CGR), and number of pods per plant were increased with extended weed-free maintenance period. Consequently, maximum soybean yields were obtained when weeds were controlled for more than six weeks, but a relatively high level of ;soybean production was attained with only two weeks of weed free maintenance.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.12 no.3
• /
• pp.145-152
• /
• 1992

Phosphorus(P) cycle of Miscanthus sinensis, Sasa palmata and Artemicia princeps for perennial plants and Polygonwn thunbergii for annual plant were investigated in natural plant communities established in Andosol region. 1. Perennial plants contained about 50-80 % P of the maximum accumulated in whole plant in under ground parts as reserve P before wintering. On the other hand, annual plant returned the most part of P in plant tissues to soil and wintered with a small amount of P in only seed. 2. The storage percentage of K was low compared to P in both perennial and annual plants. And the return of K from litter to soil proceeded rapidly because of easy leaching of K. 3. Perennial plants stored a large amount of P in reserve organs before wintering and carry it over next generation, and P holded in an individual showed a yearly increase. Consequently, P was less susceptible to depressive factor for growth of perennial plants even in poor P circumstances like Andosol region, compared to annual plant.

• Korean Journal of Weed Science
• /
• v.31 no.4
• /
• pp.401-404
• /
• 2011

Bromobutide, a paddy field herbicide, can effectively control annual and perennial weeds. It has an excellent weeding effect especially against Monochoria vaginalis and Scirpus juncoides etc. When it is mixed with other herbicides controlling weed spectrum and application timing can be broaden. Bromobutide has stable weeding effects regardless of field and weather conditions, and there is almost no phyototoxic effects to rice.

• Korean Journal of Weed Science
• /
• v.31 no.2
• /
• pp.212-219
• /
• 2011

The water dispersible granule flupoxam showed over 95% of weeding effect on the annual weeds of Poaceae such as Poa annua L., Digitaria ciliaris (Rets.) Koel and broad-leaf weeds. Efficacy of treatment had been lasted over 120 days in the $2kg\;ha^{-1}$ when it was treated from March to April while lasted over 180 days when it was treated from September to October. Because the flupoxam has a high soil absorptivity, a perfected herbicide layer is formed. This results in perfect weeding effect regardless of the presence or absence of thatch. Because the flupoxam has a different mechanism of action from the conventional herbicides such as dinitroanilines, pyridines, and carbamates, it is very effective with the alternative spray. Phytotoxicity symptoms was not observed and/or produced antocyan in new leaves in the landscape trees around the lawngrass by flupoxam treatment.

• Korean Journal of Weed Science
• /
• v.11 no.3
• /
• pp.159-166
• /
• 1991

Seven oxyfluorfen formulations were tested for control of 8 weed species and rice injury under four different water depths with various ages of rice seedlings. Among formulations tested, rice injury was slight by formulations of Elvan, Coal Slag, Chitosan and Bentonite B under 0 cm or shallow water depths, and by those of Elvan and Coal Slag under deep water conditions. Weed control was high by Bentonite A and B, and Chitosan, and was low by Elvan. Coal Slag and Sand coated oxyfluorfen, if the target weeds of oxyfluorfen are annual species, further development of Elvan, coal slag, chitosan and Bentonite A would be controlled to increase control efficacy or to decrease rice injury.

• The Korean Journal of Ecology
• /
• v.27 no.3
• /
• pp.173-177
• /
• 2004

The number and abundance of epiphytic algae growing on Sargassum thunbergii and their functional forms were examined. Thalli of S. thunbenii were collected on the nine islands of southern coast and at Gyeokpo on the western coast of Korea in summer 2001. A total of 25 species, 6 green (24%), 2 brown (8%), 17 red algae (68%) were identified in the present study. Caulacanthus okamurae, Ulva pertusa, Sphacelaria furcigera were found on the thalli of S. thunbegii that collected at the all regions. Caulacanthus okamurae, Champia bifida and Laurencia venusta grew on the lower parts of S. thunbergii thalli whereas, Polysiphonia spp. attached to the apical parts of the plants. Four functional forms, such as sheet-form (8%), filamentous-form (52%), coarsely branched-form (32%) and articulated-calcareous algal form (8%) were distinguished. The epiphytic algae on the thalli of S. thunbergii are mainly annual opportunistic algae, filamentous-form algae and smaller red algae. Also, most epiphytic seaweeds of S. thunbergii produce and release spores before pseudoperennial host plants are necrotic in late autumn.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.52 no.2
• /
• pp.169-175
• /
• 2007

This experiment was carried out to compare weed occurrence and to evaluate the field performance of some leguminous plant species under no-weeding fallow condition during summer months from middle of June to middle of August. In 2005 and 2006, the first dominant weed species was Digitaria sanguinalis, and other major weed species, such as Cyperus amuricus, Portulaca oleracea, and Amaranthus retroflexus, were similar among treatments. In both years, total shoot dry weight of weeds was the highest In the control plot, and the lowest in the cowpea plot, indicating that cowpea most effectively suppressed the growth of weeds among treatments. When the growth of four different leguminous species were compared after seeding during middle of June in 2006, cowpea and rice bean grew vigorously under no-weeding condition during hot and humid summer months, while wild soybean and hairy vetch did not. Shoot dry weight was in the order of cowpea > rice bean > wild soybean > hairy vetch. In conclusion, cowpea is a leguminous species which can be used as a green manure cover crop during summer months under no-weeding and our climate condition. Further works are needed to use cowpea as a green cover crop during summer months for various cropping systems.

• The Korean Journal of Pesticide Science
• /
• v.12 no.1
• /
• pp.1-8
• /
• 2008

The widespread and diverse sulfonylurea (SU) resistance problem has found in Korea, where one-shot-treatment herbicides such as pylazosulfuron/molinate and bensulfuron/molinate have been used continuously since 1989. The SU-resistant weeds of 7 annual weeds and 3 perennial weeds as of 2008 have confirmed in paddy fields in Korea. An effective management to SU-resistant weeds requires an integrated approach toward the weed control system, in particular, as to the drastic changes of herbicides development. Recent trend of new paddy herbicides in Japan has been developing to maximize the management of SU-resistant weeds. In the future, it is expected that the development of paddy herbicides in Korea is likely to be shifted toward the new "one-shot-treatment" included with herbicides of over 3-ways to maximize the control of resistant weeds. Bromobutide and carfentrazone are effective against sedges and broad-leaved weeds, respectively, and benzobicyclone and pyrimisulfam are effective against sedges and broad-leaved weeds.

• Korean Journal of Weed Science
• /
• v.5 no.2
• /
• pp.187-193
• /
• 1985

The experiment was carried out to evaluated the interaction between perfluidone(2-methyl-4-phenylsulphonyltrifluoromethylsulphoanilide) and bifenox(2,4-dichlorophenyl-3-methoxycarbonyl-4-nitrophenylether). A synergistic effect was found between perfluidone and bifenox. The highest synergistic effect on Echinochloa crus-galli (L.). Beauv. was obtained when 10 g a.i./10a of perfluidone was combined with 24.9 g a.i./10a of bifenox. However, bifenox should be increased to 33.3, g a.i./10a to obtain the highest synergistic effect when applied to Cyperus serotinus Rottb. at 1.0-1.5 leaf stage. Sagittaria pygmaea Miq. at 0.5-1.0sleaf stage was completely controlled by the lowest combination rate employed.

• Korean Journal of Weed Science
• /
• v.18 no.4
• /
• pp.364-370
• /
• 1998

A weed population has been mainly analyzed through vegetative analysis method in ecology. However, this method is difficult to understand a detailed feature of weed dominance in terms of region and a particular weed species. Since GIS(Geographic Information System) tool has been introduced, this constraint was able to be solved. GIS analysis for the nationwide weed survey data in 1981 revealed that most predominant weed was Monochoria vaginalis and this species predominated mostly in a western part of Chungnam, a part of Kyunggi, a northern and southern part of Kyungbuk province of Korea. Eleocharis kuroguwai which was the most predominant weed species in 1992 was occurred at southern part of Kyunggi, central and western parts of Chungnam, and southern western part of Chumnam at the GIS analysis. GIS analysis was proven to give much more detailed information than vegetative analysis of weed population and this means that a data analysis by GIS would be used for operating a high effective control strategy against target weed species and site.