• Korean Journal of Weed Science
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• v.30 no.2
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• pp.84-93
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• 2010

Petri dish and pot experiments were conducted to investigate germination and seedling emergence of Ammannia coccinea as influenced by environmental factors. The best germination of A. coccinea was obtained at $35/30^{\circ}C$ of temperature and 0 bar of osmotic potential, while no germination at temperatures of ${\leq}$ $15^{\circ}C$ and ${\geq}$ $40^{\circ}C$, osmotic potentials of ${\leq}$ -2.0 bar, or dark condition. The best seedling emergence was observed at $35/30^{\circ}C$, at which the first emergence of A. coccinea was observed at 7 days after sowing (DAS) with its maximum emergence reached at 10 DAS. No seedling emergence was observed at $15/10^{\circ}C$ with significant reduction at $40/35^{\circ}C$. Seedling emergence decreased with increasing soil depth, resulting in no seedling emergence at ${\geq}$ 3 cm. The Gompertz model well described the cumulative germination and seedling emergence of A. coccinea with time. Germination influenced by osmotic potential and seedling emergence influenced by soil burial depth were well described by the logistic model. Overall results indicate that A. coccinea is photoblastic and requires temperatures greater than $15^{\circ}C$, osmotic potential greater than -2.0 bar, and soil burial depth shallower than 3 cm for its germination and seedling emergence, which were faster than M. vaginalis but slower than E. crus-galli.

• Korean Journal of Weed Science
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• v.7 no.1
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• pp.78-83
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• 1987

This study was attempted to evaluate the combining effect of HBR (homobrassinolide) with the known growth regulators such as GA (gibberellic acid), BA(6-benzyl aminopurine), IAA (indole-3-acetic acid), B-9 (N-dimethylamino succinamic acid) and CCC (2-chloroethyl-trimethylammonium chloride) on the growth of radish hypocotyl. A single application of HBR increased hypocotyl growth as its rates increased from 0.1 to 1.0 ppm, showing a maximum increase at 1.0 ppm. GA and BA had no direct effects on hyopcotyl growth, but IAA showed some effect as its concentration increased. However, the mixed application of HBR with GA, BA and IAA increased the length of radish hypocotyl as the concentration of HBR became higher. The mixture of HBR with GA and BA showed antagonistic reaction on radish hypocotyl growth, but synergistic effect was shown in the higher rate mixture of HBR with IAA in the range of HBR at 0.03 to 0.30 ppm with IAA at 3.0 to 10.0 ppm, but antagonistic or additive response at the mixture of low rates. An increased growth of hypocotyl by HBR was ified by CCC, showing the strong antagonistic reaction, but B-9 was not able to ify HBR's effect on hypocotyl growth.

• Korean Journal of Weed Science
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• v.5 no.2
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• pp.155-163
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• 1985

Three pyrazole-herbicides, pyrazolate, pyrazoxyfene and benzophenap, were evaluated for their interaction in controlling barnyardgrass (Echinochloa crusgalli) with two chloroacetamide-herbicides, butachlor and pretilachlor. Percent inhibition of barnyardgrass growth by pyrazolate, pyrazoxyfene, and benzophenap was 44%, 64%, and 0%, respectively, when each was applied at the 1.5 leaf-stage of barnyardgrass at a rate of 3㎏ ai per ㏊ as single treatment, and the benzophenap showed 60% inhibition when it was applied at the coleoptile stage. While the lowest rate controlling the 1.5 leaf-stage barnyardgrasses by 98 to 100% of the butachlor and pretilachlor was 1.5㎏ and 200g per ㏊, respectively. All of the combinations of pyrazolate with butachlor, pyrazoxyfene with pretilachlor, and benzophenap with butachlor have shown synergistic interaction in controlling barnyardgrass on the Chisaka's isobole of 90% growth inhibition as well as on the Colby`s interaction efficacy data; synergism indices were 2.44, 1.62 and 1.52 in order. The dose combinations shown the maximal synergism were 1870g of pyrazolate with 140g of butachlor (1:0.075), 33008 of pyrazoxyfene with 338 of pretilachlor (1:0.01), and 3350g of benzophenap with 520g of butachlor (1:0.15) on the ai/㏊ basis.

• Korean Journal of Weed Science
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• v.32 no.3
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• pp.195-203
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• 2012

The essential oil was extracted by steam distillation from the aerial part of erect bur-marigold (Bidens tripartita L.), one of the noxious weed in paddy field. The composition of the essential oil was analyzed by gas chromatography-mass spectrometry. The fragrance of the essential oil was green, herbal, oily, spicy. There were 42 constituents in the essential oil：17 hydrocarbons, 6 alcohols, 6 acetates, 5 N-containing compounds, 3 ethers, 3 ketones, 1 lactone and 1 S-containing compound. Major constituents were ${\alpha}$-phellandrene (22.50%), ${\alpha}$-pinene (22.21%), 2,4-dimethyl (2,5-dimethylphenyl) methyl ester benzoic acid (15.11%), limonene (10.66%), ${\beta}$-pinene (35.43%), and ${\beta}$-cubebene (5.27%). The $IC_{50}$ value in MTT assay using HaCaT keratinocyte cell line was 0.018%. However, attachment of patch with 0.1% of the erect bur-marigold essential oil for 24 hr did not show any skin toxicity. Overall results of this study suggest that the essential oil of erect bur-marigold could be used as a source for the development of perfumery industrial products.

• Korean Journal of Weed Science
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• v.14 no.2
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• pp.81-93
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• 1994

This study was conducted to characterize herbicidal activity of the new type diphenylether compounds inducing bleaching(whitening) in relation to their chemical structures and to find out the herbicidal action mechanism. Bleaching was highly appeared in the compounds which have short chain alkyl or allyl group of cabamoyl type in meta position of A ring and nitro group in para position of B ring, and KC6361 showed the highest efficacy among these derivatives. Rice was tolerant to KC6361 at 2.0kg/ha. The applications of this compound at 0.25~1.0kg/ha provided acceptable control of the various weeds including large crabgrass, barnyardgrass, pigweed and so on. In the dark condition, KC6361 decreased carotenoid contents but increased chlorophyll in etiolated cucumber cotyledon. By the increase of light intensity, the carotenoid biosynthesis was more inhibited than the chlorophyll biosynthesis. The incorporation of $C^{14}$-acetate into lipid was slightly inhibited. Both KC6361 and norflurazon stimulated growth of dwarf rice(cv. Daneunbanju). These results suggest that both KC6361 and norflurazon may have the same action sites. To confirm this hypothesis, the changes of carotenoid intermediates in cucumber cotyledon and barnyardgrass leaf treated with KC6361 were investigated. Phytoene and phytofluene were increased but ${\beta}$-carotene was decreased, indicating that KC6361 inhibited phytoene and/or phytofluene dehydrogenase like norflurazon.

• Weed & Turfgrass Science
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• v.2 no.1
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• pp.47-54
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• 2013

The study was conducted to investigate early establishment characteristics and germination pattern of fine-textured fescues (FF) under natural room temperature and to analyze differences between alternative and natural conditions for a practical application. Six cultivars from Chewings fescue (CF), creeping red fescue (CRF), hard fescue (HF) and sheep fescue (SF) were evaluated in the study. Daily and cumulative germination pattern were measured and analyzed. Significant differences were greatly observed in germination pattern, days to the first germination, days to 60% germination, and germination percentage with environments, species and cultivars. Final germination rate was 29.7 to 80.0% under natural conditions. The first germination was initiated between 8 and 10 DAS (days after seeding) under natural conditions, being 3 to 4 days later as compared with ISTA conditions. Days to the 60% germination were 12.1 to 19.0 DAS, being 3.0 to 4.2 days slower than that under ISTA conditions. CF 'Jamestown II' was the fastest cultivar, while the slowest CRF 'Audubon'. Turf establishment speed was faster with CRF < SF < HF and < CF in order. Information on differences in germination characteristics and pattern between alternative and natural conditions would be practically useful for a golf course construction etc., when established with FF.

• Weed & Turfgrass Science
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• v.3 no.4
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• pp.329-335
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• 2014

This study was performed to study characteristics of new zoysiagarass cultivar 'Green Ever' (Plant Variety Protection Application no. 2014 - 02). 'Green Ever' was developed by selection breeding among 100 native zoysiagrasses collected in South Korea. 'Green Ever' showed specific bands (1.48 kb with OPC14 and 1.05 kb with OPD5) which were distinct from 'Anyang Joonggi' or 'Dongrae Koryogi' in RAPD analysis. 'Green Ever' was classified as Z. matrella in morphological evaluations including plant height ($6.8{\pm}0.5cm$), leaf width ($2.0{\pm}0.1mm$), height of lowest leaf ($1.9{\pm}0.1cm$) and seed length ($3.0{\pm}0.1mm$), which was similar with morphological characteristics of 'Dongrae Koryogi'. Turf quality, shoot density and chlorophyll content of 'Green Ever' were higher than them of 'Anyang Joonggi' and 'Dongrae Koryogi' under intensive management such as fairway on golf course, especially shoot densities of 'Green Ever' were excellent higher than 'Anyang Joonggi' and 'Dongrae Koryogi' during experimental periods. It could be extensively used in fairway, teeing ground of golf courses and landscape garden after further study about various environmental adaptabilities such as winter kill, wear tolerance etc.

• Korean Journal of Weed Science
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• v.32 no.2
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• pp.127-132
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• 2012

Field survey on the weed occurrence and the use of herbicides was carried out targeting 214 rice cultivating farmers at Gyeongsangbuk-do. 96.2% of farmers did machine planting in late May and this is 68.0% of total cultivating area. Spring plowing was first with 54.6%, followed by spring-fall and fall plowing with 24.8% and 15.0%, respectively. 75% of the farmers treated herbicide twice. 57.5% of them treated herbicide before transplanting and treated at post-emergence again. In case of only application, 84% of the farmers treated herbicide before transplanting. Twenty-three species were occurred at Gyeongsangbuk-do and Echinochloa spp. was the most dominant with 20.8%, Sagittaria trifolia was second with 10.4%, followed by Monochoria vaginalis and Sagittaria pygmaea with 9.9% and 9.7%, respectively. Sagittaria pygmaea was the most difficult to control followed by Echinochloa spp., M. vaginalis, and S. trifolia.

• Korean Journal of Weed Science
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• v.30 no.4
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• pp.390-395
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• 2010

This study was conducted to predict reduction of soybean yield as affected by different densities of Cuscuta pentagona. All data were fitted to Cousens' rectangular hyperbola model to estimate parameters for predicting soybean yield loss. The yield of soybean in the various densities (1 to 48 plants $m^{-2}$) of C. pentagona reduced by 80.3 to 99.7%, respectively. Among yield components, number of pods was the most significantly influenced by weed interferences. The prediction model for soybean yield as affected by weed competition was as follows: Y= 274.6783/(1+4.3522X), $r^2$=0.999 in C. pentagona. Economic threshold levels calculated using cousens' equation was 0.004 plants $m^{-2}$ in C. pentagona.

• Weed & Turfgrass Science
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• v.7 no.2
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• pp.158-165
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• 2018

This study was conducted to evaluate the control efficacy of dollar spot on creeping bentgrass after applying various amounts of tebuconazole, chlorothalonil and mixture of tebuconazole and chlorothalonil (tebuconazole+chlorothalonil). In effect of three fungicides on suppression against Sclerotinia homoeocarpa, tebuconazole and tebuconazole+chlorothalonil were found to inhibit more than 98% fungus growth on medium and 70% in chlorothalonil treatment. The control efficacy of tebuconazole at different rates of 31.25, 62.5, and $125a.i.\;mg\;m^{-2}$ on creeping bentgrass showed more than 80%. Application of tebuconazole ($125.0a.i.\;mg\;m^{-2}$), tebuconazole+chlorothalonil ($125.0a.i.\;mg\;m^{-2}+135.9a.i.\;mg\;m^{-2}$) and chlorothalonil ($135.9a.i.\;mg\;m^{-2}$) were suppressed 96%, 80%, 70% for the dollar spot severity, respectively. Correlation between application amount of fungicides and control efficacy of dollar spot was significantly positive, and suggested amount of tebuconazole, tebuconazole+chlorothalonil and chlorothalonil that might suppress more than 80% of dollar spot were calculated to 29.6, 132.2+142.8, and $157.0a.i.\;mg\;m^{-2}$, respectively.