• Asian Journal of Turfgrass Science
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• v.24 no.2
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• pp.156-160
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• 2010

This study was performed to provide useful information for kentucky bluegrass management during summer by application of plant growth regulator, Trinexapac-ethyl. Visual quality, shoot density and chlorophyll contents of treatment blocks were significantly different from those of control during summer by application of Trinexapac-ethyl. The turfgrass density of treatment was increased of 4ea/$10\;cm^2$, especially about 5ea/$10\;cm^2$ during the growth retarded period of June and July. Chlorophyll contents index and visual quality of kentucky bluegrass were improved by application of Trinexapac-ethyl during summer, too. In addition, the occurrence of foliage in rainy and high temperature season was less than that of control. However, there was no significant difference in the root length of Kentucky Bluegrass. Meanwhiles, mowing height of kentucky Bluegrass was suppressed by 38% at 2 WAT week after treatment and that there was no significant growth of treatment at 4 WAT. In this experiment, turfgrass quality was significantly better than that of control during July, even though trinexapac-ethyl wasn't applied at all in July. Consequently, periodic treatment of trinexapac- ethyl from spring would be very important to promote the turfgrass visual quality during summer which is unfavorable season on the growth of kentucky bluegrass. And it is possible to reduce mowing times at least 30% for 2 weeks by one application of Trinexapac-ethyl 0.02~0.03 ml/$m^2$ in kentucky bluegrass fairway. Additively, trinexapac- ethyl treatment can be helpful environmentally by cutting down the fertilizers and pesticides in golf course.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.1
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• pp.69-81
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• 2010

The purpose of this study is to analyze the growth characteristics of native Kentucky bluegrass (Poa pratensis L.) collected in Korea. Out of Kentucky bluegrasses collected in 2000 and 2008, eight ecotypes ("Pyengchang," "Gongju," "Inje," "Donggang," "Hwasun," "Pureundle," "Cheongsong," and "Geumsan") were planted in experimental fields and pots on May 11, 2008 and May 3, 2009, respectively, for analyzing their growth characteristics. Data such as visual quality (1-9), visual density (1-9), visual color (1-9), plant height, leaf length and leaf width were analyzed. The visual quality of "Pyengchang," "Inje" and "Gongju" were enhanced compared to the rest native ecotypes of Kentucky bluegrass. "Pyengchang" showed the best visual density while "Gongju" and "Inje" showed almost evenly favorable density. However, "Pureundle," "Cheongsong," and "Geumsan" represented loose density due to the damage from the summer climate of high temperature and humidity in 2009. As for visual color, "Pyengchang" was also ranked first, maintaining high values of at least 7.6 even in the summer climate of high temperature and humidity. "Donggang" showed good color immediately after planting in the experimental field in 2008, however, undesirable color due to the damage from the summer climate of high temperature and humidity in 2009.

• Asian Journal of Turfgrass Science
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• v.16 no.1
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• pp.1-10
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• 2002

The influence of calcium on the growth of creeping bentgrass 'Penn-Al', perennial ryegrass 'Palmer II', Kentuckuy bluegrass 'Nassou' and tall fescue 'Boonsai 2000' in greenhouse was investigated. Creeping bentgrass 'Penn-A1', Kentucky bluegrass 'Nassou' and tall fescue 'Boonsai 2000' at Ca 4.0 me/L, and perennial ryegrass 'Palmer II' at Ca 2.0 me/L showed the best shoot growth. Creeping bentgrass 'Penn-A1', perennial ryegrass 'Palmer II' and Kentucky bluegrass 'Nassou' at Ca 1.0 me/L, and tall fescue 'Boonsai 2000' at Ca 4.0 me/L showed the best root growth, and there was little or no difference between different Ca concentrations. Creeping bentgrass 'Penn-Al' and Kentucky bluegrass 'Nassou' at Ca 4.0 mea, and perennial ryegrass 'Palmer II' at Ca 1.0 me/L had the highest number of tillers, and tall fescue 'Boonsai 2000' at Ca 4.0 me/L had the highest, but there was no difference between different Ca concentrations. As application rate of Ca concentration became higher, the concent of Ca in plant tissue increased, while the content of Mg in plant tissue decreased, and the content of Fe in plant tissue increased to Ca 4.0 me/L. The Ca treatment had not effect on N, p, K, and Zn of tissue content. The wick pot applied will be to research of plant nutrition in future because utilization of wick pot has an excellent precision and convenience.

• Journal of The Korean Society of Grassland and Forage Science
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• v.23 no.3
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• pp.187-192
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• 2003

This study was conducted to investigate dry matter yield and quality of six turf grasses, and thus to apply its result into making mixed species in the mixtures. The six turf grasses were Kentucky bluegrass(Newport), red fescue(Salem), creeping bentgrass(Crenshaw), perennial ryegrass(Palmer Ⅱ), tall fescue(Rebell Jr.) and redtop(Barricuda). This experiment was carried out for 3-years at grassland experimental field of Chungnam National University. The dry matter(DM) yield obtained in tall fescue and redtop was higher than those of the other species(p<0.05). Consideration of crude protein content and dry matter digestibility(DMD), the species of high quality compared to the other species were creeping bentgrass, perennial ryegrass, and Kentucky bluegrass. The crude protein dry matter yield was higher in Kentucky bluegrass and redtop, it was lower in red fescue(p<0.05). On the other hand, digestible dry matter(DDM) yield was higher in tall fescue and redtop, but lower in creeping bentgrass and red fescue(p<0.05). Based on the result mentioned above, therefore, it is suggested that turf grasses such as tall fescue, Kentucky bluegrass and redtop are recommended as species of turf grass which could be used as bottom grasses in mixtures.

• Asian Journal of Turfgrass Science
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• v.25 no.2
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• pp.195-201
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• 2011

The seaweed (Ascophyllum nodosum) extracts and chitosan formulations were sprayed on species of creeping bentrgass (Agrostis palustris Huds) cultivar "Penn A1" and species of Kentucky bluegrass (Poa pratensis L.) mixed cultivars (Midnight 33%, Moonlight 33%, Prosperity 33%) during fall season in sod farm. Turf color, chlorophyll contents and NDVI (Normalized Difference Vegetation Index) to affect turf qualities were investigated. There were detected significantly difference on chlorophyll contents and DNVI with seaweed extracts and chitosan formulations treatments. The contents of chlorophyll and NDVI on species of Kentucky bluegrass mixed cultivars and species of creeping bentgrass cultivar "Penn A1" were significantly increased by foliar spray with chitosan formulations and seaweed extracts. There was not a significantly difference on leaf color in two species within cultivars. These results suggested that chitosan formulations and seaweed extracts may help for turfgrass managements in the golf course during fall season.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.2
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• pp.176-179
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• 1999

Trinexapac-ethyl[ 4-(cyclopropyl- $\alpha$ -hydroxy-methylene)-3,5-dioxocyclohexane carboxylic acid ethylester] is a growth-retardant for plants by inhibiting a key step in biosynthesis of GA. A treatment of trinexapacethyl generally induces a reduction in vegetative growth and also inhibits heading. In addition, the trinexapacethyl was known to enhance the freeze-tolerance in annual bluegrass, however, the mechanism is not known yet. One possible reason for the enhanced freeze-tolerance may be the antifreeze protein known to be accumulated in intercellular space of the leaf during cold acclimation. In order to see the possible in-duction of the synthesis of antifreeze proteins by trinexacpacethyl, the apoplastic proteins extracted from Kentucky bluegrass treated with trinexapacethyl were analyzed by SDS-PAGE and the presence of the antifreeze protein was observed. In addition, western analysis showed the identity of the protein induced by both a cold acclimation and a trinexapacethyl treatment. It appears that an enhanced freeze-tolerance of the turf grass by trinexapacethyl is due to the synthesis and/or accumulation of the antifreeze protein similar to the enhanced freeze tolerance induced by cold acclimation.

• Weed & Turfgrass Science
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• v.2 no.1
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• pp.88-94
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• 2013

Brown patch caused by Rhizoctonia solani AG-1 IB occurred on Kentucky bluegrass during late May through early October 2010 at golf course in Gyeongbuk Province, Korea. Disease symptoms on the turfgrass for spring season were leaf blights dying from the leaf tip, which appeared patches of brown color in the field. However, it appeared patches of dark brown color or gray brown color in fall. The fungus (B-7 isolate) of brown patch was isolated from the diseased leaf tissue and cultured on potato-dextrose agar (PDA) for identification. The young hyphae had acute angular branching and few septa and mature hyphal branches showed about 90-degree angles and development of monilioid cells, which were morphologically identical to Rhizoctonia solani AG-1 IB reported previously. DNA sequences of ribosomal RNA gene (internal transcribed spacer) of the fungus were homologous with similarity of 99% to those of Rhizoctonia solani AG-1 IB isolates in GenBank database, confirming the identity of the causal agent of the disease. Pathogenicity of the fungus was also confirmed on the creeping bentgrass and Kentucky bluegrass by Koch's postulates. This is the first report of brown patch on Kentucky bluegrass caused by Rhizoctonia solani AG-1 IB in Korea.

• Korean Journal of Weed Science
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• v.32 no.3
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• pp.222-229
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• 2012

In this study, we attempted to control invaded hetero-species turfgrass in golf courses with herbicides. Asulam sodium SP and trifloxysulfuron-sodium WG (to control creeping bentgrass in zoysiagrass), trifloxysulfuron-sodium WG (to control kentucky bluegrass in zoysiagrass), and mesotrione SC (to control creeping bentgrass in kentucky bluegrass) were selected as efficient herbicides. To creeping bentgrass, asulam sodium SP and trifloxysulfuron-sodium WG until 70 days after application (DAA), mesotrione SC until 230 DAA and to kentucky bluegrass trifloxysulfuron-sodium WG until 110 DAA; the applications showed 90% herbicidal effect. At 4 X recommended application dose, asulam sodium SP, trifloxysulfuronsodium WG (to zoysiagrass) and mesotrione (to kentucky bluegrass) showed insignificant harmful effect. With recommended dose, asulam sodium SP showed 80% control effect of creeping bentgrass in zoysiagrass until 40 DAA and trifloxysulfuron-sodium WG demonstrated 85% control efficiency until 30 DAA. Trifloxysulfuron-sodium WG controlled 85% of kentucky bluegrass in zoysiagrass until 40 DAA. Mesotrione SC with recommended dose showed 95% control efficiency to creeping bentgrass in kentucky bluegrass.

• Journal of the Korean Institute of Landscape Architecture
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• v.28 no.2
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• pp.61-70
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• 2000

The purpose of this study is to identify the proper species of turf and the ground structure for the turf sports grounds. Analysis items are particle distribution of sand and gravel, saturated hydraulic conductivity, soil hardness, and turf growth. Results of this study are as follows. 1)The particle distribution of sand used in the multi-layer rootzone is within the upper limit of the standard level. The diameter of mid-size grain({TEX}$D_{50}${/TEX})was 0.62mm and the value of uniformity ({TEX}$D_{90}${/TEX}/{TEX}$D_{10}${/TEX}) was 3.93. The particle size distribution of sand used in the single-layer rootzone was beyond the standard level as {TEX}$D_{50}${/TEX})=0.86 and {TEX}$D_{90}${/TEX}/{TEX}$D_{10}${/TEX}=8.86. 2) Saturated hydraulic conductivity of the sand was higher in the multi-layer rootzone than in the single-layer rootzone while bulk density was vice versa. 3) Surface hardness was high on Kentucky bluegrass+perennial ryegrass compared to zoysiagrass probably caused by root density. 4) Visual covering and visual rating were highly evaluated on zoysiagrass within summer while better evaluated on Kentucky bluegrass+perennial ryegrass throughout fall to spring. 5) Visual color was better evaluated on Kentucky bluegrass+perennial ryegrass than on zoysiagrass throughout the year. These studies are demanded urgently according to increase in interest in the ground and turf species of the turf sports ground because of World Cup 2002.

• Weed & Turfgrass Science
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• v.6 no.4
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• pp.313-321
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• 2017

Wetting agent is designed to reduce the surface tension of the liquid and spread more easily across or penetrate into the soil against water repellency. The effect of wetting agent to seed germination is not clear. Using germination enhancer is one of the methods to increase the germination speed of turfgrass seeds and to shorten establishment period. The objective of the study was to evaluate germination enhancer and wetting agent for quick establishment of various Kentucky bluegrass cultivars. The germination enhancer was used at two levels of 0.3 and $0.6ml\;kg^{-1}$ as low and high, respectively. Two levels of wetting agent were of 0.46, and $0.92ml\;m^{-2}$ as low and high, respectively. Germination enhancer has no synergistic effect with wetting agent. When quick establishment is required, selection of cultivar would be more effective instead of using germination enhancer and wetting agent. Among Kentucky bluegrass cultivars, 'Award' had the greatest turfgrass coverage for establishment and the greatest turfgrass color and quality based on the result of the study. When quick establishment is required, selection of cultivar would be more effective instead of using germination enhancer and wetting agent.