• Asian Journal of Turfgrass Science
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• v.25 no.1
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• pp.59-68
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• 2011

Research was initiated to investigate the effect of high water-absorbing polymer on turf grass quality of three major turfgrasses. A total of 12 treatment combinations were used in the study. Treatments were made with different rates of sand, soil organic amendment (SOA), and water-swelling polymer (WSP). Visual turf grass quality was evaluated in creeping bentgrass (Agrostis palustris Huds., CB), Kentucky bluegrass (Poa pratensis L., KB), and zoysiagrass (Zoysia japonica Steud., Zoy) grown under greenhouse conditions. Significant differences were observed among the treatments in CB, KB, and Zoy. Visual quality ratings varied with mixing rates of SOA and WSP, being maximum 5.6 in differences among them. At the end of study it ranged from 0.3 to 9.6 in CB, 0.3 to 4.0 in KB, and 0.9 to 5.8 in Zoy. Turfgrass quality pattern changed with time after seeding among treatments influenced by WSP rates. From this study, a proper rate of WSP is considered to be 5%, 5~10%, and 5% for CB, KB and Zoy, respectively. In general, overall treatment effect of WSP on turfgrass quality was highly associated with SOA 20% in three turtgrass species. When mixing sand with SOA and WSP for rootzone soil, a proper rate of SOA is considered to be 15 to 20% for CB and KB, while 20% for Zoy of warm-season grass. A further study would be required to investigate the effect of varied, gradual mixing rates of WSP on growth characteristics of turfgrasses grown on mixtures of sand, SOA, and WSP before a field application.

• 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.

• Weed & Turfgrass Science
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• v.2 no.4
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• pp.395-401
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• 2013

This study was conducted to evaluate the selective control of creeping bentgrass invaded in Kentucky bluegrass by applying several herbicides and recovery of Kentucky bluegrass by sand injection seeding method. Selective herbicides such as mecoprop, triclopyr-TEA, imazaquin, bentazone and penosulam pyrazosulfuro-ethyl and non-selective herbicides such as glyphosate, paraquat dichloride and glyphsate ammonium oxyflorfen were used. Selective suppression of creeping bentgrass in Kentucky bluegrass was evaluated by turf color, chlorophyll and visual control indexes. Control of creeping bentgrass was most effective with the double dose application of triclopyr-TEA (2 Tri-T) in the selective herbicides and the 1 / 5 dose application of glyphosate ammonium oxyflorfen (1 / 5 GAO) in the non-selective herbicides. Visual control indexes by 2 Tri-T in selective herbicides and 1 / 5 GAOin non-selective herbicides were investigated 6.0 and 7.4, respectively. Treated sites were covered completely in 50 days after seeding Kentucky bluegrass by sand injection method.

• Asian Journal of Turfgrass Science
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• v.19 no.2
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• pp.65-72
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• 2005

Creeping bentgrass (Agrostis palustris Huds.) had been the problematic weed for Kentucky bluegrass (Poa pratensis L.) fairway since it shows light green color all year. Experiment was carried out to determine the best herbicides combination to control creeping bentgrass in Kentucky bluegrass. fairway without injury. To investigate the efficacy of herbicides, five post-emergence herbicides of asulam WG ($87.6\%$), imazaquin SL ($20\%$), fenoxaprop-P-ethyl EC ($7\%$), mecoprop SL ($50\%$), triclopyr-TEA SL ($30\%$) and one pre-emergence herbicide pendimethalin EC ($31.7\%$) treated on 21 Sept. and 10 Nov. 2003. Kentucky bluegrass visual quality evaluated 30 and 50 days after application for phytotoxic effects of the herbicides. As a result, asulam WG (0.2g/$m^{2}$) and imazaquin SL (0.3ml/$m^{2}$) showed approximately $90\%$ of control in creeping bentgrass, but visual quality of Kentucky bluegrass significantly decreased from 20 to 50DAT (day after treatment). However, creeping bentgrass was acceptably controlled(over $80\%$) by fenoxaprop-P-ethyl EC (0.4ml/$m^{2}$)+triclopyr-TEA SL(0.3 ml/$m^{2}$) applied twice on 21 Sept. and 1 Oct. 2003 without serious injury on Kentucky bluegrass. Therefore, it is suggested that an application of fenoxaprop-P-ethyl EC (0.4ml/ $m^{2}$)+triclopyr-TEA SL (0.3 ml/$m^{2}$) may be more effective to control creeping bentgrass in Kentucky bluegrass with the least phytotoxicity by herbicides.

• Asian Journal of Turfgrass Science
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• v.22 no.2
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• pp.141-148
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• 2008

This study was conducted to investigate nutrient content at shoot and root(contained runner in zoysiagrass) in creeping bentgrass, kentucky bluegrass and zoysiagrass before turfgrass dormancy. The shoot ratio of dry weight in creeping bentgrass, kentucky bluegrass and zoysiagrass was 12%, 27% and 25% and root ratio was 88%, 73% and 75%, respectively. The orders of nutrients contained in turf-grass were N>K>Ca>P>Mg>Na in plant tissues. The proportion of nutrients in tissue of creeping bentgrass, kentucky bluegrass and zoysiagrass was 17%, 28% and 34% in shoot and 83%, 72% and 66% in root, respectively. These results showed that nutrients in turf-grass tissue was contained more than 70% in root before grasses dormancy. In turf grass management, all grasses were required to fertilize sufficiently N, $K_2O$, CaO and $P_2O_5$ before winter.

• Korean Journal of Weed Science
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• v.32 no.3
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• pp.174-179
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• 2012

The majority of turfgrass composition of golf courses are zoysiagrass, and mingle with cool-season turfgrasses have been increased. As result of mingling the species, invading problem has been raised. In this study, 50 golf courses nationwide were surveyed of grass composition and invading problem with hetero-species of turfgrasses. Among the courses, 47 golf courses have invading problem with more than one species at least. The invading problem has been issued most of golf course in nationwide. Thirty-seven courses composited with zoysiagrass; at 25 courses showed creeping bentgrass invading and at 33 courses were invaded by kentucky bluegrass. Among 47 kentucky bluegrass composition courses, 43 courses had creeping bentgrass invading problem. Invading problem within the grass species (creeping bentgrass in zoysiagrass, kentucky bluegrass in zoysiagrass, creeping bentgrass in kentucky bluegrass); 14, 12, and 21 courses were detected single species, two species, and three species invading problem, respectively.

• Weed & Turfgrass Science
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• v.5 no.2
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• pp.101-104
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• 2016

Curvularia leaf blight of creeping bentgrass (Agrostis stolonifera) putting green by caused Curvularia trifolii was observed in Hapcheon, Korea. In July to September 2014, curvularia leaf blight developed on leaf blades of creeping bentgrass as small water-soaked lesions that subsequently turned into dark-colored, necrotic spots. The spots were expanded and became gray, grayish-brown, or light brown, circular to oblong lesions with purple to dark brown borders that often were surrounded by a yellow halo. The necrotic lesions coalesced, became irregular in shape and caused tip or complete blighting of the leaves. Blighted leaf blades appeared grayish-white to tan. The fungus was identified by morphological characters and 16S rDNA sequencing as C. trifolii. Conidia of the pathogen were short, with predominantly 3-septa, straight or often curved, with end cells frequently paler than intermediate cells. Size of the 3-septate conidia in culture are $26{\sim}28{\times}11{\sim}12{\mu}m$. Pathogenicity of the fungus was proved by artificial inoculation on the host. This is the first report of C. trifolii causing leaf blight on creeping bentgrass in Korea.

• Asian Journal of Turfgrass Science
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• v.25 no.1
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• pp.43-47
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• 2011

Creeping bentgrass (Agrosis stolonifera L.) is regarded to be the most widely used cool-season turf grass species grown on golf greens and fairways in temperate climates of North America. Creeping bentgrass is highly susceptible to the fungal disease 'dollar spot' caused by Sclerotinia homoeocarpa. Dollar spot is a foliar disease favored by conditions of high humidity, warm days, and cool nights. Studies using Aliette Signature (Fosetyl Aluminum formulated with a green pigment) mixed with another broad-spectrum fungicide do not always provide additional visual quality benefits compared to the fungicide alone. The exact mechanism for improved summer visual quality, when it occurs, is not known. Fertility management and environment likely contribute. The object of this study is to evaluate fungicide strategies for control of dollar spot and effect on visual quality during summer and on an L-93/G-2 creeping bentgrass green. Nine fungicide combinations were used for this study. Disease control and visual quality by fungicides was evaluated on an established G-2/L-93 creeping bentgrass green at 3-hole Sunshine Golf Course in Lemont, IL. All fungicide combination showed excellent dollar spot suppression except Fore throughout the study. Visual quality of greens by addition of Aliette Signature is enhanced when bentgrass growth is compromised and slow. Dollar spot levels in Fore plots increased to 30% on 14 August, and was no different than untreated plots. Unacceptable quality by Fore was due to lack of dollar spot control.

• Asian Journal of Turfgrass Science
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• v.26 no.2
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• pp.116-122
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• 2012

The study was conducted to know whether turfgrass wear tolerance, growth, and quality could be improved by the application of silicon and potassium. First, turf responses to silicate and potassium were evaluated by several parameters such as, turf visual quality, root length, shoot density, and dry weight under the field condition. Second, turf responses to traffic frequencies were examined by turf growth (root) length, shoot density and dry weight) and soil hardness under the field condition. Finally, under traffic stress condition, the effects of silica and potassium application on wear tolerance were evaluated through the methods described above. Creeping bentgrass (Agrostis stolonifera) rooting were significantly improved by silica. The root length was enhanced by an increase in potassium silicate application. Certain level of light traffic is beneficial while frequent traffic cause serious adverse effect on visual quality of bentgrass. Under a traffic stress condition with 10 times of footing a day for 30 days, silica and potassium increased turf visual quality by 6.38% and 10.25% respectively when compared to the control. Silica and potassium treatment on trafficked plot increased turf visual quality by 11.4% and 10.2% respectively in comparison with the control with significant reduction of wear injury from the traffic. A co-application of potassium silicate with potassium sulfate provided the enhanced visual quality of turf as compared to application of silica or potassium fertilizer, respectively.

• Asian Journal of Turfgrass Science
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• v.23 no.2
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• pp.307-316
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• 2009

Creeping bentgrass (Agrostis palustrics Huds.) is cool season turfgrasse that is used for putting green in golf course. Creeping bentgrass cultivars are difficult to distinguish with the same species because of similar morphological characters and low level of genetic diversity. The SCAR markers using the specific DNA can be useful for differentiating between creeping bentgrass cultivars. Five RAPD primers were used for specific band detection among creeping bentgrass cultivars, penncross, penn A-4, crenshaw, L-93, CY-2, T-1. The pairs of SCAR primers for six cultivers were designed by the specific sequences of the bands that amplified by RAPD. Three of the six SCAR primers could not make the use as SCAR primers because the specific false bands were detected in all cultivars. The remaining pairs of SCAR primer, CY850F/R, T700F/R, L2900F/R, amplified the specific band at expected size for three cultivars, CY-2, T-1, L-93, respectively. The CY850F/R primer amplified a band of 850bp in CY-2 cultivar, the T700F/R primer amplified a band of 700bp in T-1 cultivar, and the L2900F/R primer amplified a band of 2.9kb in L-93 cultivar. In this study we developed the SCAR markers to identify and distinguish the inerseeded creeping bentgrass cultivars in a golf course green.