• Weed & Turfgrass Science
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• v.4 no.3
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• pp.243-248
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• 2015

This study was conducted to investigate the ability for weed control of the shoot extract of sorghum (Sorghum bicolor (L.) Moench) and developing a sustainable weed management in organic farming. When the dried shoot powder was mixed with soil and treated with 2 cm above the soil surface, the germination for Echinochloa crus-galli, Digitaria cilialis, Abutilon theophrasti and Amaranthus retroflexus was inhibited maxium 40%. The growth inhibition of germinated seedlings in the A. theophrasti and A. retroflexus was maxium 30% while it was less than 30% in the E. crus-galli and D. cilialis. Shoot extracts at rates above $25mg\;ml^{-1}$ was effective to inhibit germination of D. cilialis, A. theophrasti and A. retroflexus. The shoot extract concentration required for 50% of germination inhibition was $60mg\;ml^{-1}$ in the E. crus-galli, while it was less than $10mg\;ml^{-1}$ in the D. cilialis, A. theophrasti and A. retroflexus. For the foliar application, 11 adjuvants were tested at 0.5% and DOS70, TM15 and TDE7 were most effective adjuvants for the shoot extracts. DOS70 was most effective and provided up to 60% of weed control efficacy for the tested four weed species. Though herbicidal efficacy of sorghum shoot was not enough to give a proper weed control, it can be expected that long term use of sorghum shoots can provide gradual decrease in weed seeds and weed density.

• Weed & Turfgrass Science
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• v.5 no.3
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• pp.105-110
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• 2016

This paper provides the current status of weed science and prospects for the development of weed science based on the research trends presented at the 7th International Weed Science Conference in 2016. Approximately 520 researchers from 59 countries, including Korea, participated in the conference and presented 625 papers in nine research areas. Major research topics were herbicide resistance, weed ecology, weed management in agricultural and non-agricultural lands, herbicide spray technology, and non-chemical weed control. Studies on herbicide resistance presented more than 30% of all papers presented. Particularly, resistance to non-selective herbicides, such as glyphosate and glufosinate-ammonium, and non-target sites of resistance mechanisms were the main subjects of the herbicide resistance research area. Moreover, the conference focused on research concerning herbicide resistant weeds of staple crops of the world (corn, wheat, and rice). Arylex was introduced as a new compound which has a mode of herbicidal action similar to synthetic auxin. Three compounds being developed as HPPD inhibitors were studied for ways to reduce their toxicity and tested as mixed with safeners. Additionally, parasitic weeds, which are not native to Korea, are an expanding research subject in the world. Although 45 years have passed since the first report of herbicide resistance in 1970, herbicide resistance remains a serious problem in most intensive cropping systems of the world and will continue to be a major area of study in the future.

• Korean Journal of Agricultural Science
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• v.38 no.2
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• pp.191-198
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• 2011

Herbicidal effects and crop selectivity of aqueous leaf extracts of sorghum (Sorghum bicolor L.) were evaluated against several weed species for developing sustainable weed management in organic farming. Aqueous sorghum leaf extracts were highly phytotoxic to different weed species. No broadleaf weeds were germinated in the concentration of 5 fold or higher concentrated sorghum leaf extracts and 90% of seed germination was inhibited within that range in grass species. Sorghum leaf extracts strongly inhibited the growth of different weeds by pre-emergence and foliar applications in greenhouse condition. Foliar application of sorghum leaf extracts had a higher inhibitory effect than the pre-emergence application. Broadleaf weed species were more susceptible than grasses to the application of sorghum leaf extract in foliar applications than grasses. Galium spurium, Erigeron candensis, and Rumex japonicus were completely killed at the highest concentrated sorghum leaf extract both in pre-emergence and foliar application. Most broadleaf weed species were inhibited more than 80% at pre-emergence application at 50 fold concentrated sorghum leaf extract. G. spurium, E. candensis, R. japonicus, Eclipta alba, Plantago asiatica and Portulaca oleraeea were most susceptible to sorghum leaf extract in foliar application. Growth of most broad leaf weed species was suppressed by greater than 90% at 50 fold concentrated sorghum leaf extract. Most crop species were tolerant to sorghum leaf extract but shoot growth was slightly reduced by the application of 40~50 fold concentrated extracts, Sorghum leaf extract may used to control weeds in organic fanning without affecting the growth of crop.

• Journal of Ecology and Environment
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• v.36 no.3
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• pp.167-172
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• 2013

A Two-year field experiment was carried out in 2009 and 2010 to evaluate the effects of different densities of wild oat and nitrogen (N) rates on oilseed rape yield and yield components. Experimental design was split plot with three replications. Increased nitrogen rates up to 150 kg N/ha caused an increase in oilseed rape grain yield in weed-free plots (4.26 t/ha; 1t = $10^3kg$), while even at the lowest density of wild oat (15 $plants/m^2$), increasing N fertilizer only up to 50 kg/ha led to a significant increase in grain yield. Wild oat growth was favored by high levels of N. Intraspecific competition reduced biomass, 100-seed weight and number of tillers of wild oat. Both lower N rate and intraspecific competition had negative effect on wild oat growth but the weed was still able to produce a considerable number of tillers and vigorous seeds. It showed that wild oat possess a notable adaptive plasticity and can allocate a greater proportion of its resource toward reproductive organs even under resource shortage conditions and, thus, it may increase the competitive ability of the weed over the crop.Our results suggest that effective weed management should be done to prevent wild oat seed production in crops preceding oilseed rape as well as to control the weed at early season in oilseed rape fields.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.2
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• pp.80-84
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• 2002

In spite of simple and cheap cultivation method, water broadcast-seeded rice demonstrates uneven and unstable seedling establishment per unit land area and requires more herbicide and labor-input for weed control. Three experiments were conducted in a phytotron at 18$^{\circ}C$ to evaluate the adaptability of seed-mat mulching cultivation technologies in water seeded rice for the uniform seedling establishment and the inhibition of weed occurrence without herbicide application. Five different kinds of mat with different mesh sizes and fabric properties were tested. The emergence of rice was the highest in Lawn-mat treatment, being comparable with the control, in which seeds were sown without mat. The Lawn-mat also exhibited the lowest mat tension. Mat tension may influence the emergence of rice. And once it was soaked in water, it didn't maintain its original shape any more. The emergence rate of rice was the lowest in Safer-mat treatment. In Lawn-mat treatment, which was the most effective for rice emergence in the first study, the differences of emergence and seedling establishment of rice depending on the seeding position (upper, beneath, and between mats) treatments were negligible, while they were higher in dry seeds than in pre-germinated seeds treatment. The emergence as affected by the kinds of mat also showed the same trend when tested using barnyard grass. Depending on the kinds of mat, the inhibition effect of weeds was the greatest in Safer-mat and the poorest in Lawn-mat. These results strongly suggest the possibility that the uniform seedling establishment and weed management without chemical could be achieved simultaneously by seed-mat mulching through the combination of effective mat for the emergence of rice and another efficient mat for the inhibition of weed occurrence. This possibility was also tested in the field.

• Korean Journal of Plant Resources
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• v.22 no.2
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• pp.123-127
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• 2009

This study was carried out to investigate the classification and the growing characteristics of biennial weed species in a newly formed transplanting lawn grass land. Measuring size in the experimental plot was $1{\times}1m$ in the 9 different locations, and experimental design was randomized complete plot with 3 replications. The results obtained are summarized as follows. 1) Weed species in a newly formed lawn field are consisted of 29.4% of Cruciferae, 29.4% of Compositae, 23.5% of Caryophyllaceae, 11.8% of Gramineae, and 5.9% of Labiatae family 2) Emerging percentage of weed species are consisted of 47.1% on October, 41.2% on November, 5.9% on both September and December, respectively. 3) Distribution rate about flowering time of weed species was in order of 58.5% on May, 23.5% on April, 11.8% on March, and 5.9% on June. 4) Weed species were grouped according to the plant height. It was observed that below 20cm, 20-40cm, 40-60cm and above 60cm of plant height were 23.5%, 47.1%, 17.6% and 11.8%, respectively.

• Korean Journal of Plant Resources
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• v.33 no.3
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• pp.200-219
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• 2020

We performed taxonomic reviews and habitat circumstances survey for 41 un-introduced environmentally harmful plants (as designated by the Ministry of Environment, Korea in 2016). For this purpose, we investigated plant specimens from several herbaria and performed a field survey in the southeastern region of the United States. Base on the result, we presented the most comprehensive results of weed risk evaluation and taxonomic description up to now as well as classification keys for 11 species to apply the regulation management of putative invasive alien species - Centaurea maculosa Lam., Centaurea diffusa Lam., Mikania micrantha Kunth. (Asteraceae), Cenchrus echinatus L., Neyraudia reynaudiana (Kunth) Keng ex Hitchcock, Brachiaria mutica (Forsskål) Stapf, Vulpia bromoides (L.) Gray, Lolium persicum Boissier & Hohennacker, Setaria palmifolia (J. Konig) Stapf (Poaceae), Prosopis glandulosa Torr. (Fabaceae), Fallopia baldschuanica (Regel) Hobub. (Polygonaceae).

• Korean Journal of Plant Resources
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• v.34 no.6
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• pp.616-632
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• 2021

We performed taxonomic reviews and habitat circumstances survey for 41 un-introduced environmentally harmful plants (as designated by the Ministry of Environment, Korea in 2016). And we investigated plant specimens from several herbaria and performed a field survey in the southeastern region of the United States. Based on the result, we presented the most comprehensive results of weed risk evaluation and taxonomic description up to now as well as classification keys for 11 species to apply the regulation management of putative invasive alien species - Senecio madagascariensis Poir., Sphagneticola trilobata (L.) Pruski, Ageratina riparia (Regel) R.M. King & H. Rob. (Asteraceae), Andropogon gayanus Kunth (Poaceae), Echinocystis lobata (Michx.) Torr. & A. Gray (Cucurbitaceae), Salvinia minima Baker (Salviniaceae), Vincetoxicum rossicum (Kleopow) Barbar. (Asclepiadaceae), Asparagus asparagoides (L.) Druce (Asparagaceae), Alternanthera pungens Kunth (Amaranthaceae), Salpichroa origanifolia (Lam.) Thell., and Lycium ferocissimum Miers (Solanaceae).

• Korean Journal of Weed Science
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• v.32 no.3
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• pp.188-194
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• 2012

Field experiments were conducted to investigate the competition relationships of main paddy weeds with transplanted rice grown in paddy conditions. Data were used to predict crop yield as a function of weed density using a rectangular hyperbola model and determine weed economic threshold (ET) levels. The rectangular hyperbola (equation 2) was fitted to rice yield to estimate weed-free rice yield ($Y_o$) and weed competitivity (${\beta}$). Its competitivity for M. vaginalis was 0.0007445, 0.0005713, 0.000988 and 0.0008846 in Daejeon, Suwon, Iksan and Naju, respectively. The competitivity at harvest represented by parameter ${\beta}$ ranged from 0.001611 in Naju to 0.002437 in Iksan for S. trifolia. The ET levels of main paddy weeds in machine transplanted rice cultivation were well estimated based on the herbicides applied and its application cost. Therefore, our results can be used to support decision-making on herbicide application for weed management in transplanted rice cultivation.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.4
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• pp.581-590
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• 2011

Organic farming is rapidly expanding worldwide. Crop growth in organic systems greatly depends on the functions performed by soil microbes, and nutrient supply weed suppression by green manure crops input. Four red-pepper production systems were compared: 1) bare ground (conventional system); 2) hairy vetch monoculture; 3) rye monoculture; and 4) hairy vetch-rye mixture. Soil inorganic N reached the peak at 30 DAI and hairy vetch monoculture was the highest ($192mg\;kg^{-1}$) and soil total carbon was fluctuated sporadically during the experiment. Carbohydrate and phenolic compounds in soil kept significantly higher in green manure crops systems from 10 DBI to 30 DAI, however the level was the maximum at 10 DBI (carbohydrate) and 30 DAI (phenolic comounds). Incorporation of green manure crops residue enhanced soil microbial biomass C and N throughout the growing season except that MBN in rye was reduced after incorporation. Green manure crops systems suppressed weed occurrence and, in particular, it was prominent in rye monoculture. Mineral elements composition and production in red-pepper fruits were markedly decreased in green manure crops systems although hairy vetch monoculture has come close to bare ground (NPK-applied). Therefore, it was suggested that higher biomass production should be performed not only to improve soil quality and suppress weeds but to yield suitable red-pepper fruits in green manure crops-based organic farming.