• Asian Journal of Turfgrass Science
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• v.24 no.1
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• pp.24-30
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• 2010

We investigated occurrence of yellow patch for early spring season of 48 cultivars in 5 species of turfgrass, most popularly used in Korea golf courses. Only yellow patch disease caused by Rhizoctonia cerealis was occurred naturally from late fall season. Perennial ryegrass and creeping bentgrass cultivars showed susceptibility from yellow patch in early spring, respectively. However, among There was no significantly different between the other species. Creeping bentgrass, 'Pennlinks II' cultivar was the most susceptible. Yellow patch symptom showed reddish brown with margins in color and patch showed size from 5 cm to 50 cm in diameter. Based on our results, Yellow patch showed large differences among cultivar and each turfgrass species.

• Asian Journal of Turfgrass Science
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• v.6 no.2
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• pp.99-111
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• 1992

Yellow patch as leaf blight caused by binucleate Rhizoctonia occured in bentgrass (Agrostis Palustris Huds), zoysiagrass (Zoysia japonica Steud) and Kentucky bluegrass (Poa pratensis L.) from several golf couses in Korea. Binucleate Rhizoctonia was isolated from the infected lesions and was identified Rhizoctonia cerealis. Rhizoctonia cerealis infected crown, stem and leaf tissue, and the symptom was light yellow circular patch upto 1 m in diameter on bentgrass golf green. Individual infected leaf near the margin of patch developed first red and finally turn brown. As zoysiagrass lawn, the symptom was 30~40cm circular patch that occured zoysiagrass shooting time as spring, and there could not sheeted in severe lesion. In case of sheeted, zoysiagrass was first irregular leaf sopt and finally dead. Hypha diameter of Rhizoctonia cerealis was $2.5~6.3\mu\textrm{m}$(average $3.8\mu\textrm{m}$) and colar was white to buff. Monilioid cell size was $5.8~12.5$\times$13.8~37.5\mu\textrm{m}$. Sclerotia size was 0.2~2.0mm and color was white to brown. Optium temperature for the hypha growth was $23^{\circ}C$. There was a little difference in pathogenicity among the isolates.

• Korean Journal of Agricultural Science
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• v.38 no.2
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• pp.243-248
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• 2011

This investigation was conducted to develop an integrated disease management system against large patch disease occurred in a golf course. Large patch, brown patch, and Rhizoctonia blight sometimes are used interchangeably by turfgrass managers and researchers, Large patch disease of zoysiagrass is caused by a soilborne fungus called Rhizoctonia solani. Although this fungus is very similar to the one that causes brown patch disease of cool-season turfgrasses in mid-summer. Large patch development is favored by high thatch and soil moisture. Avoid overwatering the turfgrass, especially in the fall or early spring. Poorly-drained areas are very susceptible to injury from large patch and should be reconstructed (draining tiles, etc) to avoid soil saturation. However, control of yellow patch with fungicides is normally not recommended because the disease has only cosmetic effects and symptoms are usually very short-lived. Therefore, we reviewed the symptom of large patch to look for control method by soil management method.

• 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 society of oceanography
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• v.39 no.1
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• pp.96-106
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• 2004

A total of 116 surface sediment samples were obtained on the Yellow Sea and analyzed for grain size and geochemical elements in order to interpret the present sediment transportation. Thirty-nine cores and 3,070 line-km shallow seismic profiles are analyzed for sedimentary records of Yellow Sea in the past. Results show that the boundary of sediment transport between Korean side and Chinese side is about between $123^{\circ}E$ and $124^{\circ}E$. The similar result is produced from Shi et al. (in this publication). Two cyclonic patterns of surface sediments are recognized in the northeastern and southwestern Yellow Sea, while the strong front zone of the mud patch and sandy sediments are found in the southeastern Yellow Sea (the southwestern part of Korean coasts). The formation of fine-particle sediment packages, called for Northwest Mudbelt Deposit (NWMD), Hucksan Mudbelt Deposit (HSMD) and Jeju Mudbelt Deposit (JJMD), are resulted from eddies (gyres) of water circulations in the Yellow Sea. NWMD has been formed by cyclonic (anticlockwise) eddy. NWMD is composed of thick, homogeneous, relatively semi-consolidated gray clay-dominated deposit. On the other hand, HSMD and JJMD are formed by anticyclonic (clockwise) eddies. They are thick, homogeneous, organic-rich gray, silt-dominated deposit. Both core and surface sediments show that the middle zone across Chinese and Korean side contains bimodal frequency of grain-size distribution, indicating that two different transport mechanisms exist. These mud packages are surrounded by sand deposits from both Korea and China seas, indicating that Yellow Sea, which is the shallow sea and epicontinental shelf, is formed mostly by sand deposits including relict sands. The seismic profiles show such as small erosional/non-depositional channels, sand-ridges and sand-waves, Pleistocene-channelfilled deposits, a series of channels in the N-S major channel system, and thick Holocene sediment package, indicating that more complex sedimentary history exists in the Yellow Sea.

• 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.

• Mycobiology
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• v.44 no.4
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• pp.330-334
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• 2016

In 2010, disease symptoms, including necrotic lesions on stems and leaves with circular yellow-brown or irregular brown color patches, were observed on cool-season turfgrass at golf courses (OHCC) and the Daegu University research farm in Gyeongbuk, Korea. We isolated the causal agent and identified it as Waitea circinata var. zeae by morphological characterization and molecular analysis. To the best of our knowledge, this is the first report of brown patch caused by W. circinata var. zeae on cool-season turfgrass in Korea.

• Asian Journal of Turfgrass Science
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• v.12 no.1
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• pp.23-30
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• 1998

174 isolates of soil microorganisms were isolated from E-golf club from Apr.1997 through Oct. 1997. And 27 strains of them were selected through the inhihition test of mycelial growth. In the same period, soil-borne diesease pathogens, "Rhizoctonia", causing Large patch, Brown patch, Spring dead spot, and Yellow patch were isolated from the diseased areas in E-golf and S-golf club. The antagonistic activity of the strains against the pathogens was tested to select the excel-lent antagonists. In contact with the fungicides, the survivability of the antagonists was tested to assess the compatibility of the antagonists with the pesticides. The results were as follows: 1.Suppression of Rhizoctonia by Antagonists. Antagonistic activity of 27 strains against the pathogens was: tested in vitro. In the result, 3 isolates(B-7, B-15, B-41) of bacteria and 2 isolates(F-5, F-47) of fungi were superior to the rest. 2.Compatibility of the antagonists: with the fungicides: With 13 kinds of pesticides widely using Golf Club, Compatibility of 5 antagonists: were finally tested to select the strains: that mostly survived in contact with pesticides. In the results:, two of five strains: were selected : one strain was bacteria B-15, the other strain was fungi F-47. 24h after the mixing with pesticides:, these two strains were shown to survive at 90% level and these were identified as Bacillus and Trichoderma, respectively. And the most compatible pesticides: with the antagonists were shown to Polytoxin-D thirarn(s:urvivability 99.4%) and Validamycin-A (survivability 98.6%). Keywords:Antagonist, Large Patch, Trichoderma, Compatibility, Fungicide.Fungicide.

• Asian Journal of Turfgrass Science
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• v.9 no.3
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• pp.235-252
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• 1995

Turfgrass Rhizoctonia blight is a severe disease in golf courses in Korea. Attempts were made in 1989 to 1994 to identify the Rhizoctonia species associated with turfgrass blights and also to examine their epidemiology. A total of 120 Rhizoctonia isolates collected were identified as R. solani AG1, R. solani AG2-2, R. cerealis(AG-D) and R. oryzas from brown patch, large patch, yellow patch and white patch, re-spectively. R. solani AG1 was mostly associated with brown patch of cool-season grasses. and most frequently isolated in June through July and also in September. R. solani AG2-2 was isolated exclusively from zoysiagrasses from April to November, most frequently in June through July and October through November. R. cerealis was isolated frequently from both creeping hentgrass in March through April and in November, and zoysiagrass in April and July. Thermophilic R. oryzae was isolated only from creeping bentgrass in August, although with very low frequency. R. solani AG2-2 was strongly pathogenic specifically to Korean lawngrasses(Zoysia japonica, Z.matrella, Z. tenuifolia), but non-pathogenic to creeping bentgrass(Agrostis palustris), bermudagrass (Cynodon dactylon), Kentucky bluegrass(Poa pratensis), perennial ryegrass(Lolium prenne), and creeping red fescue(Festuca rubra subsp. ruhra L.). R. cerealis was strongly pathogenic to zoysiagrass and bentgrass only, but was isolate-specific i.e., from non-pathogenic to pathogenic, for other turfgrasses. The mycelial growth was optimum at relatively high temperature ranges of 25~30$^{\circ}C$ for R.solani AG1, AG2-2 and R. oryzae, while the mycelial growth of R. cerealis was initiated at $^{\circ}C$ and almost ceased at or above $^{\circ}C$.

• ALGAE
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• v.34 no.4
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• pp.315-326
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• 2019

Northeastward drifts of massive Sargassum patches were observed in the East China Sea (ECS) and Yellow Sea (YS) by the Geostationary Ocean Color Imager (GOCI) in May 2017. Coverage of the brown macroalgae patches was the largest ever recorded in the ECS and YS. Three-dimensional circulation modeling and Lagrangian particle tracking simulations were conducted to reproduce drifting trajectories of the macroalgae patches. The trajectories of the macroalgae patches were controlled by winds as well as surface currents. A windage (leeway) factor of 1% was chosen based on sensitivity simulations. Southerly winds in May 2017 contributed to farther northward intrusion of the brown macroalgae into the YS. Although satellite observation and numerical modeling have their own limitations and associated uncertainties, the two methods can be combined to find the best estimate of Sargassum patch trajectories. When satellites were unable to capture all patches because of clouds and sea fog in the ECS and YS, the Lagrangian particle tracking model helped to track and restore the missing patches in satellite images. This study suggests that satellite monitoring and numerical modeling are complementary to ensure accurate tracking of macroalgae patches in the ECS and YS.