• Asian Journal of Turfgrass Science
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• v.25 no.2
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• pp.133-137
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• 2011

Winterkill can be defined as any injury including freeze stress kill, winter desiccation, and low temperature disease to turfgrass plants that occurs during the winter period. The major damages from winterkill were low temperature kill, crown hydration, and winter desiccation. Low temperature kill is caused by air and soil temperature. Soil temperature affect more severe to turfgrass than air temperature because low soil temperature cause fetal damage to turfgrass crown. Crown hydration is a form of winter injury in which intercellular water within the plant freezes and causes physical injury to the cell membrane and wall. This is eventually resulted in dehydration of cell. Winter desiccation is the death of leaves or whole plants due to drought during the winter period. To reduce winterkill damage, cultivar selection is very important. If changing cultivar is not allowed, cold temperature hardiness needs to be increased by providing nutrients especially phosphorus and potassium in the late fall. Turf cover is effective way to reduce winterkill damage. Remaining snow is positive process to reduce winterkill damage by insulating soil temperature. The previous researches reported many materials as turf cover such as straw, polypropylene, polyester, and wood mat. Aeration and topdressing is one of the process against winterkill. Both methods are mainly conducted to reduce thickness of thatch layer. In recent, relatively new materials called black or winter topdressing sand are used to protect soil temperature from low air temperature and thaw ice crystal that may remain in soil.

• Journal of International Academy of Physical Therapy Research
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• v.1 no.1
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• pp.58-64
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• 2010

The purpose of this study was to investigate the distribution of trigger points(TrPs) on athletes with various sporting background. To achieve the purpose, a study was carried out through a survey from 180 athletes involved in 6 selected sports at Yong-In University. Selected sports included Judo, Taekwondo, Kendo, Ssi-reum(Korean traditional wrestling), Boxing, and Golf. An interview type survey and physical examination were conducted with each thirty athletes from each of the selected sports groups. Technical statistic(SPSS 15.0) was used to analyze the distribution of TrPs on these athletes. The most common TrPs observed in muscles of Trapezius, Quadratus Lumborum, Quadriceps in Judo. In Taekwondo, it was on the trapezius and triceps surae. Kendo athletes had TrPs at sites of trapezius, brachioradialis and triceps surae. Ssirem athletes were found to have TrPs on trapezius, deltoid and quadrates lumborum. In boxers, TrPs appearing at trapezius and brachioradialis were observed. Finally, Golf players were seen to have TrPs at trapezius, quadrates lumborum and brachioradialis. Hence, the analysis shows that there are significant differences of the distribution of TrPs according to the different sport items of the athlete.

• Asian Journal of Turfgrass Science
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• v.17 no.2_3
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• pp.87-97
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• 2003

The growth characteristics of creeping bentgrass seeded in the seaside landfill golf course are as follows. 1. As a result of analysis on the chemical characteristics of soil mixture used for turfgrass ground in this experiment, soil pH was 7.9, which is somewhat higher than the creeping bentgrass reference value of pH 5.5∼6.5; T-N(%) was 0.02, which is proper for the reference value, and trace element too lacked. 2. The cultivar with the fastest water infiltration was Seaside II recorded as 226.2cm/sec, while that with the slowest water infiltration was Pennlinks recorded as 141.1 cm/hr which was too faster than the USGA water infiltration reference value of 15∼30cm/hr. For the surface hardness of turfgrass ground with different cultivars, no statistically significant variation was found between the Penncross grass and the Pennlinks recorded as 18.6mm and 19.1 mm, respectively. The soil penetration was the highest in Pennlinks recorded as 7.6kg/$\textrm{cm}^2$ and lowest in Penn A-1 as 6.1kg/$\textrm{cm}^2$. 3. As a result of evaluation on visual quality at the early stage of growth, Penncross showed the most excellent visual quality compared to the others. However, Penn A-1 showed the most excellent visual quality at a late stage of growth around Sep. 17, 2003, and it was also excellent in the evaluation of visual color. Seaside II showed higher density around the root and the longest root length and was highly resistant to salt compared to others, but the initial sprouting rate was not satisfied, and the visual quality in the summer season was inferior to others. 4. As a result of measurement of the traffic injury, Penncross showed the most tolerant to the traffic stress and Pennlinks showed the most susceptible.

• Asian Journal of Turfgrass Science
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• v.26 no.2
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• pp.135-139
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• 2012

Creeping bentgrass (Agrostis stolonifera) is one of the most popular turfgrasses for high-quality playing surface such as putting green on golf courses and athletic fields. Continues damage such as divot injury on creeping bentgrass is major issue to maintain golf course properly. Although plentiful researches to maximize divot resistance have been reported, minimal research has focused on relation between nitrogen (N) sources and divot resistance. The study was conducted to determine the effect of N source for turfgrass divot recovery and overall tee performance. Eleven fertilizer treatments as N sources were applied to creeping bentgrass 'Penncross'. Before the first application, divot injuries were simulated by removing a core of soil and turfgrass from established plots and backfilling with native soil. Data collection included turfgrass color and quality. N release speed did not influenced divot recovery. Frequency of urea application had no effects on divot recovery. Urea with split application had no difference with no treatment for divot recovery. Polyon product especially polyon mini (41-0-0) had the best performance for divot recovery and for maintaining better turfgrass quality. Overall, small particle size of slow-release N form would influence creeping bentgrasss to recover divot damage.

• Asian Journal of Turfgrass Science
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• v.21 no.2
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• pp.137-146
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• 2007

Traffic causes more and more stress and injury to grasses on golf course green in Korea due to the increased playing. This study compared the effect of fertilizer component (Nitrate, Phosphate, Potassium) on turfgrass growth and quality golf course green under traffic stress during early winter. Experiment was conducted by using different fertilizer components for 2 months(Oct. 1 to Nov. 30, 2005). Turfgrass leaf color, leaf texture, density and traffic tolerance were evaluated visually, and the root length(cm) and tiller density(tiller/$cm^2$) were measured. Creeping bentgrass(Agrostis palustris cv. 'Seaside II') fromthe nursery of Incheon Grand Golf Club was used. Results of this study are as followings: 1). Turfgrass color was the best in A6(20-15-10) and A5(15-15-10) treatments in the N study. Leaf texture was not different among treatments. Turf quality and traffic tolerance were the highest In A5 and A6. Root length was the longest(15.8cm) in A6 (20-15-10). Root length increased with nitrogen levels. 2). Turf color of A9(5-7.5-5) and A10(15-22.5-15) was darkest in the comparison of P study. Leaf texture was the best in A4(10-15-10) and A9. Turf quality was the best in A10. A7(10-0-10). 3). In general, to recover turfgrass damage on the putting greens during low temperature period, fertilizer amount need to be increased; and nitrogen is better than phosphate and potassium for that purpose.

• Weed & Turfgrass Science
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• v.2 no.4
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• pp.402-407
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• 2013

Bermudagrass (Cynodon dactylon.) is one of the most difficult weedy species to control in turfgrass because it's high tolerant to various environmental and management stresses. This experiment was performed to find the integrated weed management including cultural practices to suppress bermudagrass in Zoysiagrass matrella (L) Merr. As results, two sequential applications of Fluazifop-P-butyl 0.05 ml $m^{-2}$ + Triclopyr-TEA 0.5 ml $m^{-2}$ and Fenoxaprop-P-ethyl 0.1 ml $m^{-2}$ + Triclopyr-TEA 0.5 ml $m^{-2}$ applied on 20 days intervals were evaluated the primary option for bermudagrass suppression and turfgrass injury was acceptable in zoysiagrass. In both treatments, turf injury was observed during 30days after the first application and almost recovered at 40days. While Fenoxaprop-Pethyl 0.1 ml $m^{-2}$ + Triclopyr-TEA 0.5 ml $m^{-22}$ were lightly phytotoxic to zoysiagrass in chlorophyll content test, there was no growth inhibition of zoysiagrass. Verticut practice (4 mm depth) just before herbicides application where zoyisagrass is contaminated with bermudagrass was not helpful to reduce turf injury in this experiment. However, alone verticut management was utilized to decrease about 12-14% bermudagrass population. Thus the application of Fenoxaprop-P-ethyl 0.1 ml $m^{-2}$ + Triclopyr-TEA 0.5 ml $m^{-2}$ which are permitted for turfgrass after zoysiagrass is perfectly recovered from turf injury by verticut practice should be utilized for bermudagrass reduction in zoysiagrass.

• Asian Journal of Turfgrass Science
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• v.22 no.1
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• pp.65-74
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• 2008

Traffic management is becoming an important issue in turfgrass practise on golf course. The objective of this study was to investigate the combined impact of different traffic times and types of fertilization. Traffic treatment was applied in morning (AM), noon, and afternoon (PM). Fertilizers used include faster-release fertilizer (21-17-17) and slow-release fertilizers (12-6-18, 11-3-22, 20-3-20, 10-3-10). Experiment was conducted from Oct. 1 to Nov. 30, 2005 on a nursery putting green of Incheon Grand Golf Club. The growth and quality of creeping bentgrass (Agrostis polustris cv. 'Seaside II') were evaluated on visual leaf color, leaf texture, shoot density, and root length. The measurement at 20 days after treatment, turfgrass color and leaf texture showed the best result on 10-15-10 + Noon-traffic plot. Turf quality and traffic tolerance were not different at Am and Pm traffic treatment. However, traffic stress in early morning and late evening caused the most severe damage to the turfgrass. Shoot density was the highest in 10-15-10 + Noon-traffic treatment but root length was not different among treatments after 30 day measurement. Among the fertilizers, slow release fertilizer resulted in higher turf quality and traffic tolerance than fast release fertilizer, however, shoot density did not showed a significantly different. For the fast recuperation of turfgrass from traffic injury in the early winter, it is recommended to avoid early morning and late evening traffic such as cup replacement and other maintenance practise. It is also recommended to delay the first tee-up time and ending early for last tee time during cold weather season.

• Korean Journal of Weed Science
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• v.1 no.1
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• pp.78-83
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• 1981

This study was attempted to determine the major weed species occurring in Korean turfgrass, Zoysia japonica Steud. and to evaluate the most effective means for controlling them. More or less 40 weed species were determined to occur in Korean turfgrass. In terms of quantity and frequency of occurrence, Trifolium repens L., Digitaria sanguinalis (L.) Scop., Draba nemorosa var. hebecarpa Lindbl, Erigeron canadensis L., and Cyperus amuricus Max were observed to be the major weeds. Simpson's index, 0.306 was obtained to be the major weeds. Simpson's index, 0.306 was obtained in the golf course, Jinryang, Gyungsan-gun, meaning that no specific weed species were dominant, but in Kyungpook National University campus, Trifolium repense L. was a single dominant species, indicating Simpson's index, 0.776. The most effective herbicides to control Trifolium repense L. and other broad leaf weeds were MCPP [2-(2-methyl-4-chlorophenoxy) propionic acid), followed by 2,4-D (2,4-dichlolophenoxy acetic acid). Increased rates of both herbicides increased markedly their effectivity against weeds, with very slight injury against turfgrass. MCPP at 2.8 kg(a.i.)/ha gave excellent control without any injury and 2,4-D at 1.0 kg(a.i.)/ha.

• Asian Journal of Turfgrass Science
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• v.23 no.1
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• pp.35-44
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• 2009

This study was carried out to examine the growth performance of 4 species of cool-season grasses and 4 species of zoysiagrasses under salt injury in Seo-san reclaimed area. Grasses were grown on the plots with capillary water interruption layer (WCWIL) and without capillary water interruption layer (WOCWIL) soil systems. Cool-season grass and seeding-type zoysiagrass plots were seeded on 6 Jun, 2006. Vegetative zoysiagrass 'Junggi' was established by sprigging and 'Senock' and 'Millock' were plugged. Electric conductivities of irrigation water (ECw) ranged from 0.28 to $3.3\;dS{\cdot}m^{-1}$. Electric conductivities (ECe) of the soil with capillary water interruption layer and without capillary water interruption layer ranged from 0.55 to $9.4\;dS{\cdot}m^{-1}$ and from 1.84 to $9.4\;dS{\cdot}m^{-1}$ respectively. Leaf color, turf quality, coverage rates, and growth rates were rated visually for 2 years. Zoysiagrass 'Junggi', creeping bentgrass, zoysiagrass 'Senock' and 'Millock' showed acceptable growth at salty fairway condition, while Kentucky bluegrass, perennial ryegrass, Kentucky bluegrass mixed with perennial ryegrass, and seeded zoysiagrass 'Zenith' showed establishment rates below 70%. These results will be useful when choosing turf grass species and cultivars for the golf courses in reclaimed land area.

• Asian Journal of Turfgrass Science
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• v.22 no.2
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• pp.149-160
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• 2008

This study was carried out to examine the growth performance of 10 cultivars of creeping bentgrass under salt injury in Seo-san reclaimed area. Turfgrass performance studies included 10 creeping bentgrass cultivars (T-1, L-93, Penn A1, Pennlinks II, Seaside II, Declaration, Penn A4, Crenshaw, Dominant, and Penncross). Ten creeping bentgrass cultivars were grown on a USGA recommended research green. Plots were seeded on May 31, 2006 at the rate of $7\;g{\cdot}m^{-1}$. Electric conductivities of irrigation water (ECw) and soil (ECe) were ranged from 0.28 to $3.3\;d\;S{\cdot}m^{-1}$ and from 0.25 to $3.5\;d\;S{\cdot}m^{-1}$ respectively. Leaf color, turf quality, coverage rate, and growth rate were checked under the salty condition in reclaimed land for 2 year. Creeping bentgrass cultivars of T-1, Penn links, and Crenshaw presented dark green color and Penn A1, Declaration showed lighter green color. Penn A1, Penn A4 and L-93 exhibited the highest overall turfgrass quality. Average visual coverage was 75.3% after eleven weeks after seeding. Dominant, L-93, and Penn A1 resulted in higher visual coverage compared to the other cultivars. There was no difference in density among cultivars at 1 year after establishment. However, Declaration, Penn A1, T-1, and L-93 showed higher density compared to the other cultivars at 2 years after seeding. Creeping bentgrass showed different quality, density and color in salty soil (ECe: $0.25-3.5\;d\;S{\cdot}m^{-1}$) and from application of salty irrigation water (ECw: $0.28-3.3\;d\;S{\cdot}m^{-1}$) conditions. These results will be useful where selecting green cultivars for the golf courses in reclaimed land area.