• Weed & Turfgrass Science
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• v.5 no.1
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• pp.29-34
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• 2016

Large patch disease in Zoysia japonica Steud. is the most destructive disease in turfgrass. For large patch management, it has been dependent on chemical controls but pesticides are harmful to soil, water and biodiversity. In this study, we evaluated 4 Streptomyces spp. strains (S2, S5, S8 and S12) which were selected in previous studies using metagenome approaches. Root colonization of the strains, large patch suppressing effect and the pathogen density change in actual golf course were investigated to evaluate biological control potential of the strains. All strains exhibited reliable root colonization ability that strains populations were higher than $6log\;cfu\;g^{-1}$ in turfgrass rhizosphere. The pathogen density, with S8 treatment, was detected average of 0.7 after a week and average of 1.2 after 4 weeks. Disease control and suppressive the pathogen population by S8 strain showed higher efficiency than other strains. S8 was applied in an actual golf course for the large patch control and pathogen density. The pathogen density in S8 treatment plot was detected below 1.6 per toothpick and lower compared with untreated plot. The results indicated that pathogen density was suppressed by S8 and the stain has great potential as a biological control agent for the large patch.

• Korean journal of applied entomology
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• v.43 no.1
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• pp.61-70
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• 2004

Environmentally sound control of Japanese lawngrass cutworm, Spodoptera depravata with Korean entomopathogenic nematodes (Heterorhabditis sp. Gyeongsan, Steinernema carpocapsae GSNI , S. glaseri Dongrae, S. longicaudum Nonsan, and S. monticolum Jiri) was evaluated in the laboratory and field. In addition, effect of turf height on the pathogenicity of entomopathogenic nematodes and density of ant (Formica japonica) and spine-tailed earwigs (Forficula scudderi) were investigated in the field. The corrected mortality of 3rd instar of S. depravata larvae was 53.3% to 66.7% 5 days later after treatment of entomopathogenic nematodes. $LC_{50}$ value of S. carpocapsae GSN1 and S. monticolum Jiri against 3rd instar of S. depravata was 6.9 and 3.9, respectively. Pathogenicity of S. carpocapsae GSN1 was different depending on larval stages, i.e., mortality of 2nd instar was the highest representing 73.3% but decreased from 3rd instar. Turf height affected pathogenicity of entomopathogenic nematodes. Mortality of 4th instar of S. depravata was 40.0% by S. carpocapsae GSN1 and 33.3% by S. monticolum Jiri, and 83.3% by fenitrothion, respectively, in the turf height of 14mm, but those were lower in 45mm. The corrected mortality of S. depravata larvae was lower at the entomopathgenic nematode plots than fenitrothion plot in the distribution field of Formica japonica. However, reduction rate of F japonica was higher in fenitrothion by 56.7% compared with 0% in S. carpocapsae GSN1 and 6.7% in S. monticolum Jiri. Turf height influenced control of S. depravate in S. carpocapsae GSN1 and fenitrothion. Control value of S. carpocapsae GSN1 was 62.2% in the turf height of 3-4cm, but not effective at all in 6-8cm and 12-14cm. However, there was not significantly different in fenitrothion plots. Forficula Scudderi was also reduced only in fenitrothion plots. Reduction rate was 100% in 3-4cm, 41.7% in 6-8cm, and 16.7% in 12-14cm, respectively.

• Asian Journal of Turfgrass Science
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• v.20 no.1
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• pp.33-40
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• 2006

Many soil amendments have been used nowadays to improve physical and chmical condition of turf soil, which might ultimately optimize turfgrass growth in golf courses. This study was carried out to Investigate the effects of new organic soil amendment containing pig excreta 50% and sawdust 50% on growth of zoysiagrass (Zoysia japonica L.) and kentucky bluegrass (Poa pratensis L.) in greenhouse. Three applicable treatments with soil mixtures of 10, 20, and 30% (v/v) animal organic soil amendment (AOSA) with sand, were tested for chemical property, physical property, visual quality and root length of zoysiagrass and Kentucky bluegrass. As results, application of $10{\sim}30%$ AOSA mixtures were proper to grow turfgrass in soil nutrition. Especially, the treatment with 20% AOSA mixtures showed 0.7% in organic matter, which meets to green standard of USGA. Also, 30% AOSA mixtures was 1.1% in organic matter, which might be desirable for zoysiagrass-planted golf courses in Korea. It was turned out that addition of AOSA decreased the hydraulic conductivity in soil physical property Because the sand possess high hydraulic conductivity, it is recommended to combine $10{\sim}30%$ AOSA with sand in order to sustain soil balance. The treatment with $10{\sim}30%$ AOSA noticeably increased visual quality of both zoysiagras and Kentucky bluegrass during 90 days. However, treatments with either 20% or 30% AOSA were effective to develop root length of zoysiagrass but treatments with 20% AOSA were more effective than that of 30% AOSA mixtures to promote root length of Kentucky bluegrass at 60 days. In conclusion, considering all vital factors such as visible quality, root growth, organic matter content, and economical efficiency, was taken, it is recommended that a $20{\sim}30%$ mixture of AOSA with sand is good for the growth of zoysiagrass and 20% mixture for Kentucky bluegrass.