• Asian Journal of Turfgrass Science
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• v.24 no.2
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• pp.125-130
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• 2010

Dollar spot and brown patch disease are the most economically important disease for highly maintained turfgrass area such as golf courses. Previous researches indicated that various natural fertilizers are good nitrogen (N) sources and they may lead to turf disease suppression because disease suppression by natural N sources may be due to microbial activity increased. Increased microbial activities in soil reduce the activity of plant pathogen. The objective of this study was to evaluate efficacy of various N sources to suppress dollar spot and brown patch on creeping bentgrass. The seven N sources and fungicide combinations were investigated for turf disease suppression. $Emerald^{TM}$ and $ProStar^{TM}$ were applied for the applications of fungicide combination. No differences were found on turf quality among N source treatments. However, there was significant difference on turf quality between fungicide combination and fungicide combination plus urea. Overall, N source had no significant effects on suppression of dollar spot and brown patch. Although there were a few differences among N source treatments, fungicide treatments were needed for turf disease suppression for highly maintained turfgrass area such as golf courses.

• Asian Journal of Turfgrass Science
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• v.25 no.2
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• pp.237-242
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• 2011

The 2011 Japanese Society of Turfgrass Science was divided in oral presentation, sectional meeting and small symposium, and the total 55 subject was announced. The oral presentation was reported physiological ecology of turf, disease and weed; field management; pesticidal activity and spectrum of new turf pesticides. Above all, there was presentation that investigated control method of necrotic ring spot of new turf disease and Cyperus brevifolius, annual bluegrass and mouse-ear chickweed. In addition, the control effect of new registration fungicide (Furametpyr) and herbicides (S-metolachlor, Flucetosulfuron and Foramsulfuron) were announced. There was various information interchange through 4 kinds of subjects of a golf course, ground turf, a urban park greens and ground cover plants greening by the sectional meeting, and the genetic resource of turfgrass discussed by small symposium. Specially, park greens sectional meeting was announced about the radioactive material contaminated on mechanism and effectively removal method of the radioactivity contaminant from public park, school ground and domestic lawn.

• Journal of the Korean Institute of Landscape Architecture
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• v.31 no.3
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• pp.107-113
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• 2003

Ecological control can contribute to the sustainibility of vegetation management systems by reducing the input currently derived from non-renewable fossil energy sources. The use of turfgrass mixtures is an important tool in turf management. Turfgrass mixtures of two or more compatible and adapted species provide improved tolerance to pest and environmental stress, more so than monostands. The objectives of this study were to evaluated turf insects, pests and zoysia large patch control by turgrass mixtures. In April 2001 and 2002, plots were inoculated with 50g of Rhizoctonia solani AG2-2LP inoculum. Inoculum were treated within a 29cm diamater circle at Zoysia japonica, Zoysia japonica, Poa pratenis, or Festuca arundinacea mixtures. After four weeks, disease severity in each plot was determined. plot area visual ratings were assessed visually on a linera 0 to 100%. In August 2001 and October 2002, turf insects and pests in each plot were investigated in 10cm deep soil cores with 8cm diameters using hole cut. Zoysia large patch affected zoysiagrass monostands more severly than zoysiagrass and cool-season turfgrasses mixtures. It was suggested that the barrier effect of cool-season turfgrass suppressed zoysia large patch in the mixture of zoysiagrass and cool-season turfgrasses. Also, warm-season and cool-season turfgrasses mixtures suppressed insect populations more efficiently than warm-season turfgrass monostands.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.8 no.5
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• pp.10-18
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• 2005

The research was carried out to define the morphological and growth characteristics of Poa pratensis L.(Kentucky bluegrass) 'Sewon' in native to Korea. Poa pratensis 'Sewon' was collected at the terrace land on the river in Guiman-ri, Cheongcheon-myeon, Goesan-gun, Chungcheongbuk-do on May 5, 1995. The collected Poa pratensis 'Sewon' was grown under non-mowing naturally growing condition. The morphological characteristics of Poa pratensis 'Sewon' are as follows. : The height of plant was 21.6cm but was increased to 33cm at the flowering time. The height of first node from the base was 5.0cm and the length and width of leaf were 9.6cm and 4.1cm, respectively. The length of inflorecences was 37.8cm and the length of a spike was 7.3cm. Based on these morphological characteristics, Poa pratensis 'Sewon' was defined to dwarf~medium and coarse texture type Kennturky bluegrass. 1 to 9 scale of visual quality, visual color and visual density were measured. Poa pratensis 'Sewon' showed best turf qualities among native Kentucky bluegrasses. In spring and fall growing season, Poa pratensis 'Sewon' were measured to be excellent performances for turf qulities similar to foreign excellent quality cultivars such as Midnight, Nuglade and Brilliant Kentucky bluegrasses. But turf quality of Poa pratensis 'Sewon' decreased by plant disease according to temperature increase in summe compared to foreign excellent quality cultivars. So, Poa pratensis 'Sewon' should be improved of disease tolerent quality by incessant breeding work in order to compete foreign excellent quality cultivars.

• The Plant Pathology Journal
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• v.21 no.4
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• pp.328-333
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• 2005

Paenibacillus elgii SD17 (KCTC $10016BP^T$=NBRC $100335^T$) was recently reported as a new species. Based on its inhibitory activity to Thanatephorus cucumeris AG1-1, strain SD17 was further evaluated for its potential as a biocontrol agent against soil-borne diseases of turf grasses in Korea. P. elgii SD17 showed a broad spectrum of antimicrobial activity in vitro test and suppressed development of turf grass diseases; Pythium blight caused by Pythium aphanidermatum and brown patch caused by T. cucumeris AG1-1 on creeping bentgrass (Agrostis palustris) in the growth chamber tests. Under a condition for massive culture in a 5,000 L fermenter, P. elgii SD17 reached $6.4{\times}10^8$ spores/ml that resulted in approximately $1.0{\times}10^7$ cfu/g when formulated into a granule formulation (GR) using the whole culture broth instead of water. Using the GR formulation, biocontrol activity of P. elgii SD17 was confirmed. In the growth chamber tests, the GR formulation was effective against brown patch and Pythium blight with similar level of disease severity compared to each of the standard fungicides at the application rates of 10 g/$m^2$ or above. In the field tests, compared to each untreated control, the GR formulation also effectively controlled Pythium blight, brown patch and large patch at all the application rates of 5, 10 and 20 g/$m^2$, respectively, without significant response by the application rates. However its performance was inferior to each of the standard chemical fungicides. Based on these results, we consider this GR formulation of P. elgii SD17 as an effective biocontol agent to suppress Pythium blight, brown patch and large patch of turf grasses in Korea.

• Asian Journal of Turfgrass Science
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• v.13 no.4
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• pp.201-212
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• 1999

In use of pesticides in golf courses has been increased steadily. Environmental concern as well as decrease in efficiency led the turfgrass management into an alternate approach of using beneficial microorganism to deal with turfgrass pests. This study was focused on the use of such microorganisms for improving cultural environment and minimizing the use of pesticides. Microorganisms antagonistic to turfgrass diseases were applied to zoysiagrass fairways and creeping bentgrass greens in Yusung country club. Tharch accumulation, disease occurrence, and other cultural environments were compared among the combinations of microorganisms and suppliemental N applications. The application of microorganisms antagonistic to turfgrass diseases improved turf resiliency. Thatch thickness was 3.03cm in the control plot but it was 2.11cm in plots treated by microorganisms, indicating significant effects of microorganism application on reduction of thatch accumulation. Number of microorganism that can decompose of cellulose was higher at the plots treated with useful microbial products and it was considered that existence of higher population of microorganisms resulted in reduction of thatch accumulation. In the evaluation of relationship between thatch accumulation and disease occurrence, greater thatch accumulation was observed at the golf courses which have been frequently infested by large patch. However, the rate of thatch accumulation varied among surveyed golf courses regardless of the year of turf establishment. Therefore, management practice which can be effective for reduction of thatch could result in large patch suppression. The application of microorganisms on the established turfgrasses reduced the occurrence rate of pythium blight and yellow path diseases, whereas occurrence of brown patch and dollar spot increased.

• Asian Journal of Turfgrass Science
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• v.21 no.1
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• pp.1-7
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• 2007

This study was initiated to evaluate the qualitative characteristics of creeping bentgrass(Agrostis palustris Huds.) cultivars for the climate In Korea through the NTEP(Nat'l Turfgrass Evaluation Program) data. 'L-93' showed the highest rating in overall mean visual quality. It was also the most prominent cultivar in seedling vigors, ground cover, and genetic color especially in summer. In case of turf texture, 'Penn A-1' and 'A-2' were the finest group, but the poorest group in cold tolerance. Leaf density and thatch accumulation were lower with 'Penncross', 'Pennlinks', 'Crenshaw', and 'L-93' as compared with 'Penn A'-type and 'G'-type cultivars. Resistance to moss invasion was greater with 'Penn A'-type and 'G'-type cultivars, but 'Penncross' was the least. These observations indicated that leaf density was considered to associate with the characters of turf quality, thatch accumulation and resistance to moss invasion. 'Penn A'-type cultivars were highly resistant to snow mold. Greater resistance to brown patch was associated with 'Penn A' and 'Penncross'. Higher resistance to pythium blight was found with 'Penncross' and 'Pennlinks'. 'L-93' showed higher resistance to dollar spot, but not to pythium. Therefore, these results demonstrated that turf maintenance program for the new bentgrass cultivars should be different from a conventional management for the cultivar of 'Penncross'.

• The Plant Pathology Journal
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• v.29 no.1
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• pp.93-98
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• 2013

Bacterial wilt is a vascular wilt disease caused by Xanthomonas translucens pv. poae that infects Poa annua, a grass that is commonly found on golf course greens throughout the world. Bacterial wilt causes symptoms of etiolation, wilting, and foliar necrosis. The damage is most prevalent during the summer and the pathogen can kill turf under conditions optimal for disease development. Fifteen isolates of X. translucens pv. poae were collected from northern regions in the United States and tested for virulence against P. annua. All 15 isolates were pathogenic on P. annua, but demonstrated variable levels of virulence when inoculated onto P. annua under greenhouse conditions. The isolates were divided into two virulence groups. The first group containing four isolates generally resulted in less than 40% mortality following inoculation. The second group, containing the other eleven isolates, produced between 90 and 100% mortality following inoculation. These results suggest that differences in the virulence of bacterial populations present on a golf course may result in more or less severe amounts of observed disease.

• The Korean Journal of Mycology
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• v.1 no.2
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• pp.31-33
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• 1973

On September 1972, a blight disease of turf (Arostis canina L.)was found in a golf link in Seoul Country Club at Seoul, Korea. Yellow circular patches of 15-20cm in diameter were observed and spreaded irregulary to collapse of themselves. The roots of the diseased plants were dark in color and were in a final state of decay. We isolated Curvularia sp. from the diseased plants and investigated the morphological and cultural characters. Its characters as follows: Mycelia septate, branched, hyaline or yellowish brown colored. Conidiophores septate, thin brown, unbranched. $65-270{\times}3.5-5{\mu}$. Conidia clustered at the tips of conidiophores, boat form or slightly curved with 1-5 septa, brown; both end cells hyaline; the third cell much larger than the others. $26.1-33.3{\times}9.5-10.1{\mu}$ (4 cell's conidium). The pathogenicity of the fungus to host plant was confirmed by soil inoculation method. We classified the fungus according to Gilman's method as a species Curvularia geniculata (Tracy and Earle) Boedjin.

• Asian Journal of Turfgrass Science
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• v.22 no.2
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• pp.161-170
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• 2008

Recently irregular dark-colored patches were found on the Kentucky teeing ground in a golf course in Gyunggi providence. Interestingly, blue-green algae from the leaf tissue sample containing black spot-stained symptoms were largely observed through microscopic study. In general, algae present on the upper soil surface or in the upper layer of root zone form dark brown layers of scum or crust, which invoked harmful effects to turf growth such as poor drainage, inhibition of new root development. In this observation, unlike the algae were sometime found in senescing leaves on contacted soil in July and August, the blue-green algae were detected within black spot-stained Kentucky bluegrass leaf tissues including leaf blade, ligule, auriclea as well as leaf sheath. The blue-green algae were also detected on the leaf and stem tissue adjacent to the symptomatic leaf tissues. Two species of blue-green algae, Phomidium and Oscillatoria, were greatly observed. Oscillatoria species was more commonly notified in all samples. In addition, the two species were found on a putting green showing yellow spot disease at another golf course in Gyunggi providence. The data from chemical control assay revealed that chemicals such as propiconazole, iprodione, and azoxystrobin decreased blue-green algae population and leaf spots, which finally resulted in enhanced leaf quality. All taken together, we strongly suggested that the disease-like phenomenon by blue-green algae might be very closely mediated with infection/translocation process in relation with turfgrass. It indicates that blue-green algae in turf management may play an adverse role as a secondary barrier as well as a pathogenic agent. This report may be helpful for superintendents to recognize and understand the fact that algae control should be provided more cautiously and seriously than we did previously in upcoming golf course management.