• Research in Plant Disease
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• v.12 no.3
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• pp.260-266
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• 2006

Pythium blight caused by Pythium spp. is one of major diseases in putting green of golf course. In this study, microorganisms which are anatgonistic to Pythium aphanidermatum, a pathogen of pythium blight, were selected primary through in vitro tests, dual culture method and triple layer agar diffusion method. In vivo test against pythium blight were conducted to select the best candidate biocontrol microorganism by pot experiment in a plastic house. Bacillus subtilis GB-0365 was finally selected as a biocontrol agent against pythium blight. Relative Performance Indies(RPI) was used as a criterion of selecting potential biocontrol agent. B. subtilis GB-0365 showed resistance to major synthetic agrochemicals used in golf course. Alternative application of synthetic agrochemicals and B. subtilis GB-0365 was most effective to successfully contol pythium blight. B. subtilis GB-0365 suppressed the development of pythium bight of bentgrass by 56.4% as compared to non-treated control and its disease control efficacy was 60.9% of a synthetic fungicide Oxapro(WP) efficacy. B. subtilis GB-0365 has a potential to be a biocontrol agent for control of pythium blight.

• Journal of the Korean Wood Science and Technology
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• v.38 no.3
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• pp.165-169
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• 2010

The cityward tendency of the population caused the building crowd and the skyscrapers, and destroyed the cityscape and ecosystem of the city. For this reason, many researchers studied to make more green spaces in the city. The roof greening is one of the methods to get the green spaces in the city. There are some problems in this method such as the safety load, growth of the plants on the artificial foundation, and so on. In this study, we evaluated the waste woodchips and the waste papers as a new materials for the artificial foundation. The new artificial foundation was made of the waste woodchips and the waste papers with the different ratio of mixture (woodchips, paper slurry, and fertilizer). The artificial foundation was applied to the planting of three different plants (creeping bentgrass, barley, and wheat). It was found that the growth of the plants with 1% of fertilizer was higher than other conditions. The best making condition of foundation was 40% pulp and 60% woodchips in the germination of all plants.

• Weed & Turfgrass Science
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• v.6 no.3
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• pp.262-271
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• 2017

This study was conducted to evaluate incorporation ratio of soil amendment 'Profile' to improve soil physicochemical properties and turfgrass growth. The soil amendment was added 0 (sand only), 3, 5, 7, and 10% to USGA Green-spec green sand soil. As incorporated with more 'Profile' amendment, soil electrical conductivity (EC), cation exchangeable capacity (CEC), capillary porosity and total porosity of root zone were increased than those of control, while bulk density and hydraulic conductivity decreased. Turfgrass index and clipping yield of creeping bentgrass grown in sand soil incorporated with 7% 'Profile' were improved than those of control. Correlation coefficient of turf color index and incorporation ratio of the soil amendment 'Profile' was found to show significantly positive correlation. These results indicated that application of the soil amendment 'Profile' to sand soil in golf course green improved turfgrass growth and quality by increasing CEC and porosity of root zone.

• The Korean Journal of Mycology
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• v.30 no.2
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• pp.157-165
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• 2002

Of 125 isolates collected from 35 golf courses, sensitivity of 44 isolates of Pythium species to metalaxyl was determined on corn meal agar with various concentrations of metalaxyl (0.1, 1.0, 10.0, 50.0, 100.0, and $250.0{\mu}g\;a.\;i/ml$). The isolates were able to be categorized into the sensitive and resistant groups based on hyphal growth measured in terms of colony diameters on the medium with $1.0\;and\;10.0{\mu}g\;a.\;i./ml$. When compared with hyphal growth on the medium without metalaxyl, hyphal growth of the sensitive group which included 31 isolates was inhibited by $66{\sim}98%$ on the medium with $1.0{\mu}g\;a.\;i./ml$, whereas that of the resistant group which included 13 isolates grew well and the hyphal growth was inhibited only by $6{\sim}26%$. When $10.0{\mu}g\;a.\;i./ml$ of metalaxyl was included in the medium, hyphal growth of the sensitive and resistant groups was inhibited by $82{\sim}99%\;and\;27{\sim}47%$, respectively. Occurrence of metalaxyl-resistant isolates of Pythium spp. not only from turfgrasses on golf courses but also from other crops was observed for the first time in Korea. Metalaxyl-resistant isolates occurred most frequently in P. graminicola. Control effects of metalaxyl were determined by applying metalaxyl after and before inoculation of 4 and 3 isolates of sensitive and resistant isolates of P. graminicola, respectively, to creeping bentgrass in pots. The minimum concentration of metalaxyl to control metalaxyl-sensitive isolates was $6.25{\mu}g\;a.\;i./ml$, whereas the disease caused by the metalaxyl-resistant isolates could not be controlled with $12.50{\mu}g\;a.\;i./ml$ of metalaxyl. The disease was controlled more effectively by an application of metalaxyl prior to inoculation than after occurrence of the disease.

• Asian Journal of Turfgrass Science
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• v.20 no.1
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• pp.65-76
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• 2006

Scz1, an isolate of Sclerotinia homoeocarpa, was recently reported as a novel pathogen responsible for dollar spot disease in Zoysiagrass, a warm season turfgrass. Scz1 possessed different characteristics on mycelial pigment, mycelial affinity and host pathogenecity compared to those of Scb1, a typical isolate, obtained from creeping bentgrass, a cool season turfgrass. In this study, only three isolates, Scz1, Scz2(another analogous isolate of Sclerotinia homoeocarpa from zoysiagrass), and Scb1, were examined at the molecular level using the internal transcribed spacer(ITS) and random amplified polymorphic DNA(RAPD) assays to verify their identification and genetic variation. As a result of ITS assay, partial ITS sequences of three isolates showed 94-97% similarity with a standardized ITS sequence of S. homoeocarpa registered on BLAST. In the analysis of RAPD, range value through similarity matrix was 0.167 between Scz1 and Scb1, 0.139 between Scz2 and Scb1, and 0.713 between Scz1 and Scz2, respectively. Furthermore, tendegram analysis indicated that Scz1 and Scz2, unlike Scb1, were clustered together as accompanying a high genetic similarity. In in vitro fungicide bioassay, $EC_{50}$ value representing the sensitivity degree to propiconazole, a well-known fungicide for dollar spot disease, was 0.012 ${\mu}g/ml$ for Sczl, 0.003 ${\mu}g/ml$ for Scz2, and 0.030 ${\mu}g/ml$ for Scb1. From all data taken, we concluded that both Scz1 and Scz2 belonged to one group of S. homoeocarpa, since they exhibit the same host range and high level of genetic similarity, whereas their chemical competences to a fungicide were different. This study would provide further approach for assessing genetic diversity of S. homoeocarpa isolates as well as characterizing individual isolate against chemical exposure.

• Asian Journal of Turfgrass Science
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• v.25 no.2
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• pp.223-228
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• 2011

This research was performed to investigate change of green speed according to growth of grass, for this, the method of effective green management for improvement of green speed was searched by investigating green density, soil moisture, surface hardness, and mowing height every day for 6 months. As the result of the study, reliability between, green density, soil moisture, surface hardness, mowing height and green speed were measured to be respectively 0.4742, 0.5690, 0.4632, 0.2806, i.e. soil moisture is considered as the factor which affects green speed the most. Therefore, it will be an advantageous environment to maintain soil moisture a little bit low to improve green speed within the range that does not disrupt the growth of green. In case of green density, it is considered to be effective to get a fast green speed when obtaining enough density during May~June, the most vigorous growth period and at the same time green up period. Surface hardness was confirmed that management work as rolling is a considerably effective method to increase hardness. However, rolling gives high stress to the green, combining another management work as regular hilling could be a good alternative. Reliability of green preview and green speed was 0.2806, lower than soil moisture or surface hardness. Through the results, it was confirmed that management of mowing height to be low less than 3.00 mm is helpful to improve green speed, timely, and it is advantageous to manage green speed when adjusting mowing height during the vigorous growth period of bent grass. However, considering the range of mowing height was not various, being 2.9~3.4 mm, henceforth research on investigation of green speed at more various mowing heights would be necessary. Consequently, except mowing height, other three factors, i.e. green density, soil moisture and surface hardness were investigated to have considerable level of reliability on green speed, and it is considered that each factor affects green speed respectively according to green condition and time. Accordingly, in order for the manager to maintain high speed all year round, intensive care for each factor per time unit considering green growth condition is considered to be necessary.

• 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.

• Korean Journal of Microbiology
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• v.40 no.4
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• pp.342-347
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• 2004

A bacterial strain YC4963 with antifungal activity against Colletotrichum orbiculare, a causal organism of cucumber anthracnose was isolated from the rhizosphere soil of Siegesbeckia pubescens Makino in Korea. Based on physiological and biochemical characteristics and 16S ribosomal DNA sequence analysis, the bac­terial strain was identified as Pseudomonas aurantiaca. The bacteria also inhibited mycelial growth of several plant fungal pathogens such as Botrytis cinerea, Fusarium oxysporum and Rhizoctonia solani on PDA and 0.1 TSA media. The antifungal activity was found from the culture filtrate of this isolate and the active compound was quantitatively bound to XAD adsorption resin. The antibiotic compound was purified and identified as phenazine-l-carboxylic acid on the basis of combined spectral and chemical analyses data. This is the first report on the production of phenazine-l-carboxylic acid by Pseudomonas aurantiaca.

• Korean Journal of Weed Science
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• v.15 no.2
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• pp.166-174
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• 1995

This experiment was conducted to investigate a cause of summer depression of cool season turfgrass, using nine cultivars in warm season and twenty-eight cool season turfgrasses. Even though an average of apparent photosynthesis(APS) per fresh weight was 13.09 mg $CO_2$/g/h in warm season turfgrass and 7.75 mg $CO_2$/g/h in cool season turfgrass, the Creeping bentgrass in cool season type was higher than Kikuyugrass and Bahiagrass in warm season type. The optimum temperature for the heighest APS was $30^{\circ}C$ in warm season type and $25^{\circ}C$ in cool season type. In $CO_2$ compensation point(CCP) as an index of dark respiration, it was higher in cool season turfgrass(75.6ppm) than warm season turfgrass(29.5ppm). In warm season type, even though the temperature increased from $25^{\circ}C$ to $40^{\circ}C$ the CCP was not increased. But the higher temperature rises the more increased CCP in cool season type. Dark respiration(DR) was higher in cool season type than warm season type under various temperature conditions, but the increasing ratio of DR with the temperature increment was not so much differed between two types.