• Asian Journal of Turfgrass Science
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• 제19권2호
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• pp.85-94
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• 2005

A fungal isolate was newly collected from Zoysiagrass 'Anyang-Joongji' in small circular patches on a fairway ofa golf course in Korea, which seriously occurred during the early summer period of 2005. The isolate presented on PDAmedium, named Scz1, was closely identical to Sclerotinia homoeocarpa, a casual fungus of dollar spot disease, in cool season turf grasses such as creeping bentgrass. Hereby, this study was accomplished to characterize the isolate and compare it with the fungus, named Scb1, isolated from dollar spot-infected creeping bentgrass (Agrostis palustris Huds. cv Penncross). On PDAmedium, individual mycelial appearance of three isolates was very similar except for the pigment. Mycelial pigments of Scz1 and Scz2 (another analogous isolate collected) were light pinkish on the reverse side of PDA medium but that of Scb1 was dark brownish. In a microscopic study, three isolates were barely distinguishable in the appearance of mycelia. As expected, in the temperaturesensitivity assay, all pathogens were very delicate to $32^{circ}C$ above but not to $30^{circ}C$ below, in which was explained to be one of typical characteristics in S. homoeocarpa. In an artificial inoculation assay, disease symptoms including leaf spots in Zoysiagrass were appeared within 6-7 days after inoculation through the hand inoculation method with the isolate-infested soil. Then the fungus was re-identified from the infected leaf tissues. Interestingly, inoculation of isolate Scz1 gave rise to distinct symptoms in only Zoysiagrass but not in creeping bentgrass 'Penncross' and Kentucky bluegrass 'Midnight'. The observation might be involved in host specific pathogenecity of S. homoeocarpa Scz1 to Zoysiagrass. In a chemical sensitivity assay for the isolate, Scz1, showed a high mycelial inhibition against two fungicides, iprodione and propiconazole. All results described above suggest that S. homoeocarpa Scz1 is a primary pathogen of Zoysia dollar spot disease.

• Korean Journal of Environmental Agriculture
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• 제40권1호
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• pp.49-59
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• 2021

BACKGROUND: Soil salinity causes reduction of crop productivity. Rhizosphere microbes have metabolic capabilities and ability to adaptation of plants to biotic and abiotic stresses. Plant growth-promoting bacteria (PGPB) could play a role as elicitors for inducing tolerance to stresses in plants by affecting resident microorganism in soil. This study was conducted to demonstrate the effect of selected strains on rhizosphere microbial community under salinity stress. METHODS AND RESULTS: The experiments were conducted in tomato plants in pots containing field soil. Bacterial suspension was inoculated into three-week-old tomato plants, one week after inoculation, and -1,000 kPa-balanced salinity stress was imposed. The physiological and biochemical attributes of plant under salt stress were monitored by evaluating pigment, malondialdehyde (MDA), proline, soil pH, electrical conductivity (EC) and ion concentrations. To demonstrate the effect of selected Bacillus strains on rhizosphere microbial community, soil microbial diversity and abundance were evaluated with Illumina MiSeq sequencing, and primer sets of 341F/805R and ITS3/ITS4 were used for bacterial and fungal communities, respectively. As a result, when the bacterial strains were inoculated and then salinity stress was imposed, the inoculation decreases the stress susceptibility including reduction in lipid peroxidation, enhanced pigmentation and proline accumulation which subsequently resulted in better plant growth. However, bacterial inoculations did not affect diversity (observed OTUs, ACE, Chao1 and Shannon) and structure (principle coordinate analysis) of microbial communities under salinity stress. Furthermore, relative abundance in microbial communities had no significant difference between bacterial treated- and untreated-soils under salinity stress. CONCLUSION: Inoculation of Bacillus strains could affect plant responses and soil pH of tomato plants under salinity stress, whereas microbial diversity and abundance had no significant difference by the bacterial treatments. These findings demonstrated that Bacillus strains could alleviate plant's salinity damages by regulating pigments, proline, and MDA contents without significant changes of microbial community in tomato plants, and can be used as effective biostimulators against salinity stress for sustainable agriculture.

• Research in Plant Disease
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• 제16권1호
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• pp.48-58
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• 2010

In Korea, EBI fungicides which are highly effective for control of pear scab and rust but of high risk for development of resistance have been frequently sprayed by majority of pear growers. To detect any possible resistance or reduced sensitivity in the field strains of scab fungus to five EBIs, difenoconazole, fluquinconazole, flusilazole, fenarimole and hexaconazole, sensitivity tests were conducted with fungal specimens collected in Ulsan and Naju where scab usually occurs and EBIs have been intensively sprayed for many years. As the strains for which $EC_{50}$ values of the EBIs were largely shifted from those of base-line were occasionally found, the resistant or less sensitive strains were supposed to be distributed. In the activity test for the EBIs by artificial inoculation, in which EBI-treated pear leaves on the potted seedlings were inoculated with fungal spores collected in the two regions, development of resistances to EBIs were confirmed. Since the fungal spores collected at 4 and 2 orchards in Naju and Ulsan, respectively, produced much higher disease incidence on the leaves treated with hexaconazole than those on the untreated control, those fungal specimens were determined as resistant to hexaconazole. Similar results were also obtained with two specimens from Ulsan for flusilazole.

• The Korean Journal of Mycology
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• 제24권4호통권79호
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• pp.246-254
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• 1996

Since the mid of 1980's, cultivation area and production of Ganoderma lucidum have been increased annually in Korea. However, the presence of a fungal disease has become a major limiting factor in the cultivation of Ganoderma lucidum, causing a serious economic loss. The present study was carried out to isolate and identify the pathogenic fungus to Ganoderma lucidum. Several fungi isolated from the wood logs showing typical symptoms were tested whether they are pathogenic to Ganoderma lucidum or not by cross-pairing culture method, flask inoculation method, and wood log inoculation method. The pathogenic fungus produced ascomata. Mature ascomata was spherical, dark, thick-walled, $45{\sim}95\;{\mu}m$ diameter. Asci were thin-walled, evanescent when mature, disintegrate early. Ascospores were spherical, hyaline, glaborous, thick-walled, refractive, $3.6{\sim}4.3\;{\mu}m$ in size. Conidiophores soon became abundantly septate and broke up into arthrospores, which are cylindrical, $3{\sim}6\;{\mu}m$ long and $3{\sim}4\;{\mu}m$ wide. Based on the observations under dissecting microscope, light microscope and scanning electron microscope, teleomorph and anamorph of the pathogenic fungus were identified as Xylogone sphaerospora Von Arx & Nilsson and Sporendonema purpurascens (Bonordon) Mason & Hughes, respectively. X. sphaerospora is first reported as a pathogenic fungus of Ganoderma lucidum.

• Korean Journal of Environmental Agriculture
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• 제22권4호
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• pp.255-260
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• 2003

Silicon is known to accumulate in plants and results in greater resistance to diseases and insect pests. In this study, we investigated the effect of silicate fertilizer applied in soil on the development of powdery mildew of oriental melon. Oriental melon seedlings of four-leaf stage were transplanted and grown in a plastic film house. Silicate fertilizer was applied to maintain soil available $SiO_2$ level of 200 mg/kg one week before transplanting. Fungicide triflumizol was sprayed three times; one, two, and three weeks after transplanting. Sphaerotheca fuliginea was inoculated 2 weeks after transplanting. The number of infected leaf and the number of fungal colony in leaves were measured one, two, and three weeks after the inoculation. Three weeks after the fungal inoculation, in the treatment of fungicide triflumizol. infected leaf numbers and number of colony per leaf were reduced by 10 and 58%, respectively. In the silicate fertilizer treatment, infected leaf numbers and numbers of colony per infected leaf were suppressed only by 6 and 16%, respectively, and the efficacy was lower than that of the fungicide triflumizol. The combined treatment of silicate fertilizer and the fungicide suppressed powdery mildew more effectively, and infected leaf numbers and numbers of colony per leaf were reduced by 31 and 80%, respectively. These results indicate that although silicate fertilizer itself is not much effective in the suppression of powdery mildew, it can significantly enhance the efficacy of the fungicide.

• Journal of The Korean Society of Grassland and Forage Science
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• 제18권3호
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• pp.195-204
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• 1998

This study was designed to investigate the effects of antagonistic microorganism, Bacillus subtilis, on the growth of forage seedlings in repeated cultivation soils and unrepeated cultivation soils. The field experiment was wnducted in pots in a vinyl house using repeated and unrepeated cultivation soils. Forage types were 'Suwon 19' wrn(Zea mqs L.), 'Califbmia' white clover(Tr~oIium repens L.) and 'Fawn' tall fescue (Festuca arundianacea Schreb.). Samples of white clover and tall fescue were taken h m each pot at 36 days after seeding. Samples of wm were examined at 50 days after seeding. The most active antagonistic bacterium was isolated h m forage rhizosphere soil, and selected by reference to it's antagonistic ability on the growth of pathogenic fungi, Rhizoctonia solmi and Fusarium oxyspomm, and it was identified as Bacillus subtilis. This strain strongly suppressed the growth of fungal pathogens among isolated rhizobacteria. The dry weight of forage shoots and roots cultivated in unrepeated cultivation soils was higher than that cultivated in repeated cultivation soils. The dry weight of forage was positively affected by the inoculation of the antagonistic bacterium, Bacillus subtilis, in both repeated cultivation soils and unrepeated cultivation soils. In conclusion, the growth of forage was more affected by the inoculation of the antagonistic bacterium in unrepeated cultivation soils than that in repeated cultivation soils, and bacterization of forage with B. subtilis resulted in an inrreased yield.

• Research in Plant Disease
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• 제10권4호
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• pp.260-267
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• 2004

Fusarium spp. were isolated from the postharvest fruit rot of oriental melon fruits at commercial fruit markets in Korea during 2001 to 2003. The decayed fruits were covered with the fungal mycelia and eventually soft rotted. The disease started at the fruit stalk area, the calyx end of the fruit and skin of fruit. As the disease advanced, white to pinkish mycelia covered with the surface of decayed fruit. The cultural and morphological characteristic of Fusarium spp. were compared with descriptions of those reported previously, and identified as Fusarium equiseti, F. graminearum, F. moniliforme, F. proliferatum, F. sambucinum, and F. semitectum. Pathogenicity of the isolates was proved by artificial wound and unwound inoculation onto the healthy fruits. Two days after inoculation, aerial mycelia were noticed on the wound inocultion region of the fruit and developed soft rot symptoms. Although Fusarium spp. causing fruit rot disease in oriental melon have been reported in Korea, identification of the those species was not described. Therefore, this is the first report of Fusarium spp. causing postharvest fruit rot on oriental melon in Korea.

• Research in Plant Disease
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• 제26권3호
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• pp.190-193
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• 2020

In 2014, Anthracnose symptoms were observed on fruit of pumpkin in Gangneung, Gangwon in Korea. The typical symptoms on fruit surfaces were circular lesions, brown, shriveled with salmon-colored spore masses on the spots. A fungal isolate was obtained from symptomatic on fruit and cultured on potato dextrose agar at 25℃. The color of the upper surface of the colony varied from white to gray with occurrence of salmon-colored conidial masses and was red to violet on the underside. The causal fungus of anthracnose isolated from the diseased fruits was identified as Colletotrichum fioriniae based on mycological characteristics and sequences of the internal transcribed spacer, glyceraldehyde-3-phosphate dehydrogenase, chitin synthase-1 gene, histone H3, actin gene, beta-tubulin gene region. Pathogenicity tests of the isolate were performed on pumpkin fruit by both wound and non-wound inoculation with conidial suspension (1×10⁶ conidia/ml) and incubated at 25℃. Lesions were observed on both wounded and non-wounded fruit of pumpkin after 7 days inoculation in only C. fioriniae. The pathogen was re-isolated from the lesions of inoculated fruits. To our knowledge, this is the first report of anthracnose on fruit of pumpkin caused by C. fioriniae in Korea.

• KOREAN JOURNAL OF CROP SCIENCE
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• 제23권2호
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• pp.113-117
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• 1978

An attempt was made to establish a mass-screening technique for resistance to purple seed stain .disease in soybean. Seeds sterilized in 1 : 10000 'mercuric chloride for 1 minute and transffered to Petridishes containing 20ml water agar plus 50ppm of the sodium salt of 2,4-D were inoculated by placing a small agar cube containing fungal mycelium on the seed coat of each seed. A positive correlation between natural infection of purple seed :stain and purple discoloration by seed inoculation technique was highly significant and by this technique, some native soybean collections and introduced varieties were tested for resistance to the disease. Most of the soybean varieties tested were susceptible except for the varieties Hill, Harosoy and Sac, resistant comparatively.

• The Plant Pathology Journal
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• 제33권4호
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• pp.410-423
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• 2017

Pathological interrelations of two soil-borne diseases in cucurbits (watermelon, oriental melon, shintosa and cucumber) caused by Fusarium isolates (FI) and the root-knot nematode (RKN), Meloidogyne incognita were characterized by the fusarium disease severity index (DI), RKN gall index (GI) and eggmass index (EI) in inoculation tests using FI and RKN. Virulence of FI as determined by DI at 4 weeks after inoculation was mostly in the higher order of Fusarium proliferatum F6, F5 and Fusarium oxysporum f. sp. melonis or Fusarium oxysporum f. sp. niveum with no significant differential interactions among the cucurbits and RKN co-infection. Significant increases of DI due to RKN coinfection were noticed in watermelon and oriental melon infected with F. proliferatum isolates, suggesting the DI increase due to RKN coinfection may depend upon the virulence of FI relative to aggressiveness of RKN on the cucurbits. For the coinfection of FI and RKN, GI and EI were mostly reduced logarithmically with the increase of DI, largely more in EI than GI, in all cucurbits except for shintosa. Microscopic examination of the root tissues showed histopathological features characteristic to infection types; formation of fungal hyphae and/or spores and plant defense structures (tyloses and mucilage) in variable degrees and formation of giant cells at variable developmental stages and with variable cytoplasmic depletion or degeneration which were visualized in relations with the values of DI, GI and EI. These findings will be helpful to develop control strategies of the soil-borne disease complex based on their pathological characteristics.