• Korean Journal of Agricultural Science
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• v.11 no.2
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• pp.183-189
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• 1984

This study was carried out to investigate the salt tolerance to the seed germination of 4 forage crops and their critical salt concentration. 1. The rate of seed germinations of 4 forage crops at 0.4% NaCl solution was not significantly decreased compared with control plot but the germination percentages at 0.8% NaCl solution were significantly dropped. 2. The days for germination were gradually delayed by increasing salt concentrations. 3. The growth of seedling root and shoot was slightly depressed at 0.4% salt solution but significantly depressed at 0.8% solution. At 1.2% salt solution, the seedling growth was stopped immediatly after seed germination. 4. The NaCl content in the seedling was increased at the medium containing higher amount of NaCl, however increasing rate of NaCl level in the seedling showed significant differences among the forage crops tested in this experiment. 5. The critical salt concentration to the germination of the forage crops was 0.4% to 0.8%. The perennial ryegrass showed the highest salt tolerance in the seed germination, and the tall fescue and the creeping red fescue showed medium, and the orchardgrass showed the lowest tolerance.

• Weed & Turfgrass Science
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• v.2 no.4
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• pp.408-412
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• 2013

Dollar spot caused by Sclerotinia homoeocarpa F.T. Benn. is a common and economically important turfgrass disease in South Korea. Fungicides mixture (propiconazole 25% + boscalid 47%) treatments, showing synergistic interaction, with three application rates (low: 50.3 ml $10a^{-1}$ and 97.5 g $10a^{-1}$, intermediate: 67.0 ml $10a^{-1}$ and 130.0 g $10a^{-1}$, and high: 100.5 ml $10a^{-1}$ and 195.0 g $10a^{-1}$) and two application intervals (10 and 15 days) were evaluated for control of dollar spot in creeping bentgrass golf course putting green. In both nontreated plots of field A and B, the disease has severed as 48.3 and 60.0% after the pathogen inoculation. Two fungicide mixture treatments showed significantly higher the disease control effect than a single fungicide treatment (propiconazole). Field A which showed more the disease severity but the fungicide still showed acceptable level of the disease efficacy (89.0%), significant differences in control value were not detected among treatments. The results suggest that the lower application rate of two fungicides mixture treatments may reduce the dollar spot disease severity in creeping bentgrass golf course putting green.

• Weed & Turfgrass Science
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• v.7 no.2
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• pp.148-157
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• 2018

Research was initiated to evaluate four domestic and overseas organic soil amendments (SAs) on turfgrass groundcover and density and to provide basic information on practical sports turf establishment. This study was conducted in Agrostis palustris Huds. (CB) grown in sand-based root zone. A total of 20 treatments of SA+sand were prepared by mixing 10 to 50% (v/v). These amendments were SABP (Berger Peat), SAEP (Eco-Peat), SAGS (G1-Soil), and SAPP (Premier Peat). Turfgrass groundcover and density significantly varied with SAs, its mixing rate to sand and week after seeding (WAS). Cumulative turfgrass density was variable, but a great change occurred between 2 and 4 WAS. Turfgrass density at 2 WAS ranged from 36.7 (SABP 30) to 89.7% (SAGS 20), being 53.0% in differences among treatments. However, CB reached to carrying capacity around 6 WAS. Thus, most treatments were similar to 90% or so in density. At the end of study, overall groundcover ranged between 60.7 (SAEP 10) and 96.7% (SAPP 50). Proper mixing rate was variable with SAs, being 10 and 20% for SABP and SAGS, respectively. But the optimum rate was 50% for both SAEP and SAPP.

• Weed & Turfgrass Science
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• v.3 no.1
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• pp.41-49
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• 2014

Four preparations of liquid turfgrass fertilizers were tested cool season turfgrasses during fall season. The preparations of PS-A, PS-B, PH-C and PH-D for commercial products were contained with essential nutrient elements, seaweed extract, amino acids, and humus substance. Growth and quality of creeping bentgrass (Agrostis palustris Huds cv. Penn-A1) and Kentucky bluegrass (Poa pratensis L.) mixture (Midnight 33%, Moonlight 33%, Prosperity 33%) were evaluated by normalized difference vegetation index (NDVI), root length and fresh weight, shoot density, turf color, and chlorophyll content. Three foliar sprays of 4 preparations with an interval of 7 days were made in the fall of 2013 in the sod production field at Hapchun, Korea. No significant difference among 3 preparations was found in NDVI of creeping bentgrass. However, PS-A was significantly increased NDVI of Kentucky bluegrass. Two to three applications of PS-A significantly increased chlorophyll content and turf color. Three foliar sprays of PS-A and PS-B were significantly increased the shoot density of Kentucky bluegrass on 20 days after final application. These results may indicate that the use of some preparation is beneficial in producing higher quality turfgrass sod with better color and chlorophyll content during fall season.

• Weed & Turfgrass Science
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• v.4 no.1
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• pp.58-64
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• 2015

The black cutworm, Agrotis ipsilon (Hufnagel) is a major insect pest of economic crops including turfgrasses on golf courses. The entomopathogenic nematode, Steinernema carpocapsae GSN1 strain (ScG), a Korean isolate, is an effective biological control agent for soil dwelling and greenhouse insect pests in Korea. In addition, ScG is commercially produced in Korea. We conducted laboratory, greenhouse, and field trials to evaluate efficacy of ScG against black cutworms in turfgrasses. A rate of 63 infective juveniles (Ijs) per larva killed >90% of $3^{rd}$ instars feeding in cups of artificial diet within 3 days. In greenhouse trials against cutworms feeding in pots of turfgrass, efficacy of ScG was higher against $4^{th}$ instars than against $2^{nd}$ instars (90.0 vs 81.2% mortality, respectively, at $2,000Ijs\;pot^{-1}$) in perennial ryegrass, and higher against $3^{rd}$ instars in creeping bentgrass, Agrostis palustris than in zoysiagrass, Zoysia japonica (96.7 vs 52.5% mortality at $100,000Ijs\;m^{-2}$) in pot. The corrected mortality of $4^{th}$ instar was 79.9% at the rate of $100,000Ijs\;m^{-2}$ in the creeping bentgrass in the field. So ScG could be used as biological control agent against black cutworm in turfgrass of golf courses.

• Journal of Animal Science and Technology
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• v.46 no.4
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• pp.701-706
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• 2004

The objective of this experiment was to compare the dry matter intake, nutrients digestibility and nitrogen and energy utilization of herbages harvested from turf type mixtures {tall fescue(Rebell Jr.) 40%+ perennial ryegrass(Palmer II) 20%+ Kentucky bluegrass(Newport) 10%+ redtop(Banicuda) 10%+ red fescue(Salem) 10%+ creeping bentgrass(Crenshaw) 10%} and tall type mixtures {orchardgrass(Potomac) 40%+ tall fescue(Fawn) 20%+ Festuloium braunii(Paulita) 10%+ perennial ryegrass(Reveille) 10%+ timothy(Climax) 10%+ red clover(Kenblue) 10%+ alfalfa(Vernal) 10%} by Korean native goats. This experiment was conducted by total collection method in laboratory, 2001. The voluntary DM intake per body weight were slightly higher for turf type mixtures(28.9g) than that of tall type mixtures(26.2g), but there was no significant difference. The digestibility of cellular constituents was slightly higher for turf type mixtures than that of tall type mixtures(p<0.05), but digestibility of DM, NDF and ADF did not differ between two mixtures. The retained nitrogen percent(apparently biological value) was slightly higher for turf type mixtures(56.7%) than that of tall type mixtures(56.4%), but there was no significant difference between two mixtures. Apparently retained digestible energy was slightly higher for turf type mixtures(58.3%) than that of tall type mixtures(57.9%), but there was no significant difference between two mixtures. Based on the results, the herbage utilization by Korean native goats did not showed any significant difference between two mixtures, therefore there is a possibility that herbages of turf type mixtures can be used as a roughages by livestock.

• The Journal of Engineering Geology
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• v.21 no.4
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• pp.281-293
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• 2011

We investigated the causes and characteristics of a landslide at Hwangryeong Mountain, Busan, based on aerial photos, annual precipitation data, rock fracture patterns, and geomorphic features using GIS Software, and a statistical analysis of tilted trees. The analyzed slope shows evidence of a previous slope failure event and the possibility of future failures. Although the NW-SE trending slope was relatively stable until 1975, a large-scale slope failure occurred between 1975 and 1985 due to complex factors, including favorably oriented geologic structures, human activity, and heavy rain. This indicates that a detailed study of geologic structures, slope stability, and rainfall characteristics is important for slope cuttings that could be a major factor and cause of urban landsliding events. The statistic analysis of tilted trees shows a slow progressive creeping type of mass wasting with rock falls oblique to the dip of the slope, with the slope having moved towards the west since 1985. A concentration of tree tilting has developed on the northwestern part of the slope, which could reach critical levels in the future. The analysis of deformed trees is a useful tool for understanding landslides and for predicting and preventing future landslide events.

• Journal of The Korean Society of Grassland and Forage Science
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• v.24 no.2
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• pp.137-144
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• 2004

The objective of this experiment was to suggest the optimum N fertilization level for turf type mixtures {Kentucky bluegrass(Newport) 40% + tall fescue(Rebell Jr.) 20%. + perennial ryegrass(Palmer II) 10% + redtop(Barricuda) 10% + red fescue(Salem) 10% + creeping bentgrass(Crenshaw) 10%}. The field trials were conducted from 1998 to 2000 at Chungnam National University in order to evaluate the dry matter yield and quality on the N levels(100, 150 and 200kg/ha). With increasing the N level, the average DM yields over 2-years of turf type mixtures significantly increased. The average total DM yields were obtained 6,551, 8,182 and 9,501kg/ha at N 100, 150 and 200kg/ha level(p<0.05), respectively. CP content and DMD were increased, whereas fibrous constituents was decreased(p<0.05), but CPDM and DDM yields were significantly increased with increasing the N levels over 2-year(p<0.05). Based on the results, considering the total DM yield and the quality of herbages which were incidentally produced from turf type mixtures, it can be suggested that the suitable N level was 200kg/ha. But increased N fertilizer usage for general purpose use and expenses on turf type mixtures should be considered in advance.

• Asian Journal of Turfgrass Science
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• v.15 no.4
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• pp.157-168
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• 2001

This study was carried out to investigate the offsets of pyroligneous acid on the growth of ‘Penncross’Creeping Bentgrass (Agrostis palustris Huds.) and to propose the practical use for ecologically responsive management in Korean golf courses. In the plots affected by 300, 500, and 800 times diluted pyroligneous acid, the turfgrass growth increment and the visual quality were measured at fixed periods. The data were subjected to paired samples T-test. The results summarized are as follows； 1) In leaf growth increment, density, and root spread depth, turfgrass affected by 500 and 800 times diluted pyroligneous acid were superior to the control continually. It was reliable in the statistics. Especially, 500 times diluted solutions was superior to the others. 2) In color, texture, uniformity, and recuperative strength, the visual quality of turfgrass affected by 500 and 800 times diluted pyroligneous acid were superior to the control continually. It was reliable in the statistics except the recuperative strength. Espe-cially, 500 times diluted solutions tended to be superior to the others. 3) There was no symptom of a disease in all plots. The existing management was thought to be suitable in this golf course. 500 and 800 times diluted pyroligneous acid were not thought to trigger or promote a disease, 4) After investigating the effect of pyroligneous acid on turfgrass growth, the soils of all plots were analyzed. In all plots, the chemical properties of the soils were not changed obviously. 5) Considering the results mentioned above, the practical use of 500 and 800 times diluted solutions might decrease the amount of nutrients and agricultural chemicals used in golf courses as well as promote turfgrass growth in golf courses.

• Korean Journal of Microbiology
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• v.44 no.4
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• pp.317-325
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• 2008

Recently there are difficulties in management of golf courses because of an ever increasing demand for golf as a leisure sports. Hence natural minerals as an amendment could be applied to improve and manage the physicochemical properties of the golf course soils in an environment-friendly way. In this study, quartz porphyry, which has been shown to be a good soil amendment for crop production, was tested for its effect on physicochemical properties of the golf course soil, growth of creeping bentgrass (Agrostis stolonifera) and changes of soil microbial communities in the soil. In general, amendment of 20% quartz porphyry into the soil turned out to be most effective in enhancing a proper growth of the grass leaves and roots. DGGE profile data showed that eubacterial species richness was also the highest at this level of the mineral treatment in which Actinobacteria and ${\alpha}$-Proteobacteria were the dominant phyla. This appeared to be attributed to a low level of soluble organic matter content and decreased concentration of cations such as $Ca^{2+}$, $Mg^{2+}$, and $K^+$.