• Asian Journal of Turfgrass Science
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• v.24 no.1
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• pp.9-15
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• 2010

During 2008~2009 winter season, yellow patch and gray snow mold occurred on turfgrass plants in golf courses in Kangwon and Jeonbuk provinces, respectively. The fungi associated with the diseases were identified as Rhizoctonia cerealis Van der Hoeven and Typhlua incarnata Lasch ex Fr., based on the morphological characteristics of hyphae and sclerotia. R. cerealis and T. incarnata were pathogenic to most turfgrass and crop species tested. R. cerealis infected crown, stem and leaf tissue of the host plants, and the symptom was light yellow circular patch. Individual infected leaf near the margin of patch developed red color first and finally turn brown. The symptoms caused by gray snow mold pathogen are water-soaked spots, and became a watery soft rot. Infection parts became yellow and then turned brown followed by death of the whole plant. White mycelia were developed on higher petioles, leaves, and on soil where these plant parts lay, and black sclerotia of variable size and shape formed in the mycelial mass. All isolates tested were pathogenic on most turfgrass and crop plants, and significantly different in aggressiveness. Disease severity increased with longer snow cover days on target plants, suggesting that disease severity was expressed over snow cover days. There were significant differences in disease severity among the graminious species, and among cultivars within each species, indicating varying levels of susceptibility to R. cerealis and T. incarnata.

• Journal of the Korean Institute of Landscape Architecture
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• v.35 no.1 s.120
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• pp.88-93
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• 2007

Since the 1990s, the application of Kentucky bluegrass cultivars has increased in newly-constructed Korean golf courses as opposed to the previously-used zoysiagrass. However, there have been few reports studying the selection and characterization of these Kentucky bluegrass cultivars under Korean weather conditions. A total of 12 Kentucky bluegrass cultivars were tested for their adaptability in environmental stresses during summer conditions in Korea in order to select the best Kentucky bluegrass cultivars for use in Korean golf courses. This study found that two Kentucky bluegrass cultivars ('Midnight' and 'Bluestone') maintained their green throughout the summer season and had a high degree of root density, as compared to the other cultivars tested. These two cultivars also had a good rate of coverage in the early growth period. These characteristics make them suitable for application on sports fields and golf courses, which receive many divots and the frequent replacement of turfgrass sod caused by both biotic and abiotic stress. Two other cultivars, the 'Ginney' and 'Nuglade', also displayed good visual quality and high rate of coverage under summer conditions. In conclusion, the 'Midnight' and 'Bluestone' cultivars performed well in areas including the maintenance of their green color, the number of roots and the rate of coverage during the summer months. These characteristics are necessary for golf courses sports fields, which receive many divots and requirethe frequent replacement of turfgrass. further research on a range of Kentucky bluegrass cultivars, including a sensitivity test for many pathogens and recovery rates from a variety of stresses, is required in the near future.

• 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.24 no.2
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• pp.161-164
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• 2010

Dollar spot, caused by Sclerotinia homoeocarpa F.T. Bennett, is the most economically important turfgrass disease on golf courses in North America due to its persistent nature. Fungicides, plant growth regulators, and other products were evaluated for preventative control of dollar spot and the secondary effects on brown patch and Pythium in a mixed stand of creeping bentgrass and annual bluegrass golf course putting green. Most fungicides provided excellent control of dollar spot throughout the trial but Rhapsody alone did not provide adequate control. Civitas applied alone and tank-mixed with Banner MAXX(R) and Daconil Ultrex(R) provided acceptable control throughout the study. No phytotoxicity was observed on any of the treatments applied but a darker green color and reduction in turfgrass growth was observed in a treatment with plant growth regulator, Trimmit. Treatments that contained Civitas and the Civitas Harmonizer also exhibited green pigmentation.

• Asian Journal of Turfgrass Science
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• v.23 no.1
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• pp.111-122
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• 2009

Compound fertilizer contained slow release nitrogen was used at golf course management because of promoting turfgrass growth and decreasing fertilizing labor. But, it was hardly published about turf grass growth by its effect and form like isobutylidene diurea(IBDU) and methylene urea(MU) in golf course management of Korea. This study was conducted to investigate the effect of compound fertilizer contained slow release nitrogen such as IBDU and MU on creeping bentgrasss and the change in nitrogen in the root zone after application of fertilizers at AM turfgrass research institute with soil analysis, chlorophyll content index, leaf area index and dry weight during 5 months from July to december in 2007 year. Fertilizer treatments were designed as following; non-fertilizer(NF), straight fertilizer(CF), treatment 1(MU), treatment 2(IBDU 1), and treatment 3(IBDU 2). The every treatments were arranged a randomized complete block design with three replications. Results obtained were summarized as follows: As relative to time after N fertilizers application, ammonium and nitrate in soil were increased, but T-N was decrease. $NO_3$-N and T-N content of slow release fertilizer(SRF), the treatment MU, IBDU 1 and IBDU 2, in soil was higher than that of CF, and the change of ratio of available N and T-N by elapsed time after fertilizing SRFs and CF was higher about 5% in root zone of SF to l5days, but in root zone of SRF from 30days about $5{\sim}10%$. Compared with NF, the turf color index was increased 6.5%, 6.7%, 5.9% and 5.5%, respectively, the chlorophyll content 33.2%, 38.4%, 35.1% and 37.1%, the dry weight 76.2%, 77.7%, 69.5 and 72.3% and shoot number 28%, 52%, 56% and 51%. The chlorophyll content index of MD, IBDU 1 and IBDU 2 was increased $2.6{\sim}5.2%$ than that of CF, shoot number $18{\sim}22%$ but turf color index and dry weight was analogous to that of CF. These results showed that the SRF application was supplied nitrogen for a long time in root zone by increasing an available nitrogen, and so bring turf growth such as chlorophyll content and shoot number in creeping bentgrass.

• Asian Journal of Turfgrass Science
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• v.25 no.1
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• pp.89-93
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• 2011

This study was conducted to evaluate the effects of bastnasite nitrate fertilizer (BNF) on the growth of creeping bentgrass. Fertilizer treatments were designed as follows; non-fertilizer (NF), control (CF; compound fertilizer), RE-l (CF+0.3 $g{\cdot}m^{-2}$BNF), RE-2 (CF+0.5 $g{\cdot}m^{-2}$BNF), RE-3 (CF+1.0 $g{\cdot}m^{-2}$BNF) and RE-4 (0.5 $g{\cdot}m^{-2}$BNF). Every treatment was arranged in a randomized complete block design with three replications. In creeping bentgrass, turf qualities such as turf color index and chlorophyll index, shoot number, clipping dry weight and nutrients of tissue were measured. It was hardly affected by BNF application in investigation of chemical properties of the soil. By applying BNF, turf color index and chlorophyll index in RE-2 were increased 3.9% and 9.2% more than NF. As applied BNF on creeping bentgrass, shoot number was increased 9% in RE-4 more than NF and 22% in RE~2 more than CF. It was increased in N uptake and clipping dry weight of creeping bentgrass by supplying BNF. These results indicated that the BNF application promoted a turf qualities and a growth of creeping bentgrass by advancing N uptake and shoot number.

• Asian Journal of Turfgrass Science
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• v.25 no.1
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• pp.100-105
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• 2011

This study was conducted to evaluate the effect of developed SCB(DSCB) produced by adding N, P and K to SCB liquid fertilizer on the growth of creeping bentgrass. Fertilizer treatments were designed as follows; non-fertilizer (NF), control (CF; chemical fertilizer), 100 DSCB (250 $ml{\cdot}m^{-2}$DSCB), 80DSCB (200 $ml{\cdot}m^{-2}$DSCB) and CF+SCB (CF+250 $ml{\cdot}m^{-2}$SCB). Every treatment was arranged in a randomized complete block design with three replications. In creeping bentgrass, turf color index, chlorophyll index, dry weight, shoot number and nutrient content were measured. The results were as follows; Chemical properties of soil was hardly affected by DSCB and SCB applications. Turf color index and chlorophyll index in DSCB and SCB treatment were increased by 2~3% and 14~19% than those in NF, respectively, and similar to those of CF treatment. As applied to DSCB and SCB, shoot number was increased by 7%, 21%, 36% in 100 DSCB, 80 DSCB and CF+SCB than NF, respectively, and by 19% in CF+SCB than in CF. Supplying DSCB and SCB increased dry weight of creeping bentgrass, compared to CF treatment. Compared with CF, nitrogen and P content in tissue was increased in CF+SCB and in 80DSCB, respectively. These results suggested that applications of DSCB and SCB promoted turf quality and growth of creeping bentgrass by enhancing N and P uptake and shoot number.

• Asian Journal of Turfgrass Science
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• v.18 no.1
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• pp.1-13
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• 2004

The growth characteristics of cool season turfgrass in the seaside landfill golf courses with the single-use of kentucky bluegrass and mixed-use with kentucky bluegrass and perennial ryegrass in the coast line are as follows. Water infiltration rate was higher in the kentucky bluegrass single-use groups recorded as 95.6∼125.9cm/hr than in the roups mixed with kentucky bluegrass and perennial ryegrass recorded as 180.3∼386.2cm/hr. The surface soil hardness and the soil penetration were ranged from 16.6 to 18.0mm and from 6.0 to 7.3kg/cm$^2$, respectively. The cultivar that showed the most excellent visual quality and visual color in the kentucky bluegrass single-use groups was Midnight(KB2), whose density around the root was relatively excellent, as well. North Star(KB3) known as highly resistant to salt was the secondarily excellent cultivar. Brilliant(KB1) had visual quality of about third grade, however, it seemed profitable to develop turfgrass ground by virtue of its high density. As of April 26, 2003, when 2 weeks had passed after seeding, the visual quality was better in the groups mixed with kentucky bluegrass and perennial rye grass than in the kentucky bluegrass single-use groups. The most excellent visual color was found in Midnight(KB2)+Brightstar SLT(PR2) among the groups mixed with kentucky bluegrass and perennial ryegrass. On August 4, 2003, a disease was found from one experimental group in Blackstone(KB4) and expanded into more than 50cm of diameter.

• 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.

• 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.