• The Plant Pathology Journal
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• v.25 no.2
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• pp.121-127
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• 2009

Since July 2005, survey of chestnut ink disease was carried out in chestnut stands located at southern parts of Korea. Dead chestnut trees showing inky ooze on necrotic trunks were found in two different locations. In order to isolate and identify the causal fungus, infected tissues and soil samples around dead or dying trees were collected and placed on Phytophthora-selective medium. Rhododendron and chestnut tree leaves were used as a bait to isolate the fungus from soil samples by attracting zoospores in soil suspensions. On V-8 culture medium, the isolates produced homothallic oogonia with protuberances ($34.0-46.2{\times}21.9-26.7{\mu}m$) abundantly, but did not produced sporangia. Mass production of sporangia was possible by immersing agar plugs with actively growing mycelium in the creek water at $18^{\circ}C$ for 3 days. Sporangia were papillate, and ovoid to obpyriform ($17.0-38.9{\times}14.6-29.2{\mu}m$) in shape. Comparison of the ITS sequences revealed that the isolates had 100% identity to the P. katsurae isolates from Japan and New Zealand and 99.6% identity to other P. katsurae isolates. All of the examined isolates from Korea were completely identical to each other in ITS sequence. Numerous sporangia were formed in filtered as well as unfiltered creek water, but no sporangia formed in sterilized distilled water. Light induced sporangia formation, but has no influence on oospore formation. Amendments of ${\beta}$-sitosterol in culture media have no significant effect on mycelial growth but significantly stimulate oospore and sporangia formation.

• The Plant Pathology Journal
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• v.33 no.4
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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.

• Mycobiology
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• v.32 no.3
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• pp.139-147
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• 2004

A severe damping-off disease of bush okra caused by Pythium aphanidermatum, was diagnosed in plastic houses in Der Attia village, 15 km southwest of El-Minia city, Egypt, during the winter of 2001. Bush okra seedlings showed low emergence with bare patches inside the plastic houses. Seedlings that escaped pre-emergence damping-off showed poor growth, stunting and eventually collapsed. Examination of the infected tissues confirmed only Pythium aphanidermatum, showing its typical intercalary antheridia, and lobulate zoosporangia. P. aphanidermatum was shown to be pathogenic on bush okra under pot and field experiments. Bacteria making inhibition zones against the damping-off fungus P. aphanidermatum were selected. Agar discs from rhizosphere soil of bush okra containing colonies were transferred onto agar plate culture of P. aphanidermatum. After 2 days of incubation, colonies producing clear zones of non-Pythium growth were readily detected. The two bacteria with the largest inhibition zones were identified as Pseudomonas fluorescens. Bush okra emergence(%) in both pot and plastic houses experiments indicated that disease control could be obtained by applying P. fluorescens to the soil or coating the bacteria to the bush okra seeds before sowing. In the plastic houses, application of the bacteria onto Pythium-infested soil and sowing bush okra seeds dressed with bacteria gave 100% emergence. In addition, This was the first reported disease of bush okra by this oomycete in Egypt.

• Korean Journal Plant Pathology
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• v.10 no.1
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• pp.54-60
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• 1994

Incidence of Rhizoctonia blight ranged from 22.2% to 100% in the golf courses at six geographical locations in Korea from 1989 to 1993. Rhizoctonia blight occurred more severly in southern area than in northern area. Fifty seven isolates of Rhizoctonia solani obtained from diseased parts of zoysiagrasses were grouped to AG2-2 by anastomosis test. Pathogenicity testes revealed that this pathogen was strongly pathogenic to Korean lawngrasses(Zoysia japonica, Z. matrella, Z. tenuifolia), but not pathogenic to creeping bentgrass(Agrostis palustris), bermuldagrass(Cynodon dactylon), Kentucky bluegrass(Poa pratensis), perennial ryegrass(Lolium prenne), and creeping red fescue(Festuca rubra subsp. rubra L.). The isolation frequency of R. solani AG2-2 fro sheaths of the infected plants was the highest by 91.67%, and that from stolons and roots was 11.13% and 5.63% respectively. The pathogen was not isolated from the leaves. Population density of R. solani in the lawn of large circular patch was highest on surface soils down to 1 cm deep with the value of 4.9$\times$104 (CFU/g soil), but below 1 cm population density decreased sharply down to 0.8~9.8$\times$103 (CFU/g soil). Horizontal distribution of propagules in turfgrass soil was higher in the margin than in center of patch, where the number of propagules was similar to these of healthy looking soils close to the margin of diseased patch. The meteorological factors influencing the outbreak of the disease were temperature, the number of rainy days and precipitation. Optimum temperature for disease development of Rhizoctonia blight in field was 20~22$^{\circ}C$, and that for hyphal growth of R. solani AG2-2 in vitro was 25~3$0^{\circ}C$. In Pusan area, Rhizoctonia blight first occurred in late April and rapidly developed in late June. The disease slightly decreased during July to August and developed again in late September in 1993. The monthly disease progress in Pusan area was similar to that in Kyeonggi province.

• Korean Journal of Clinical Laboratory Science
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• v.40 no.2
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• pp.80-85
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• 2008

Microsporum gypseum is a geophilic fungus abundant in soil throughout the world. M. gypseum has been identified for the first time in Korea at 1976. The purpose of this study was to investigate epidemiologic aspects of M. gypseum. We performed the epidemiologic study an 198 patients with M. gypseum infections in from January 1976 to December 2005. From 100,012 patients, dermatophytes were isolated as follows; Trichophyton rubrum was isolated from 86,553 (86.5%), T. interdigitale 3,991 (4.0%), Epidermophyton floccosum 1.021 (0.1%), T. tonsurans 141 (0.1%). T. mentagrophytes 3.930 (3.9%), T. verrucosum 220 (0.2%), Microsporum canis 3.879 (3.9%), and M. gypseum 198 (0.2%). Number of patients with M. gypseum by site and age were as follows; most patients infected with tinea corporis were young people under 10 years. M. gypseum were most frequently isolated in summer and autumn.

• Korean Journal of Organic Agriculture
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• v.13 no.2
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• pp.161-173
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• 2005

This study was carried out to clarify the effects of antifungal bacterial strains isolated from the greenhouse soil grown strawberry plants on the growth inhibition of plant pathogen, gray mold (Botrytis cinerea) infected in strawberry plants in Damyang and Jangheung districts. Antagonistic bacterial strains were isolated and investigated into the antagonistic activity against gray mold. Screened ten bacterial strains which strongly inhibited Botrytis cinerea were isolated from the greenhouse grown strawberry plants, and the best antifungal microorganism designated as SB 143 was finally selected. Antifungal bacterial strain SB 143 was identified to be the genus Bacillus sp. based on the morphological and biochemical characterization. Bacillus sp. SB 143 showed 59.4% of antifungal activity against Botrytis cinerea. By the bacterialization of culture broth and heated filtrates of culture broth, Bacillus sp. SB 143 showed 93.1% and 32.1% of antagonistic activity against Botrytis cinerea.

• Parasites, Hosts and Diseases
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• v.31 no.3
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• pp.293-294
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• 1993

We examined stools of 113 soldiers of Korean Army in Whachon-gun, Korea in 1992. The eggs of Clonorchis sinetris (71113) and Metqsonimw sp. (31113), and cysts of Ginrdia lomblic (41113) were detected. No eggs of soil-transmitted helminths were found. Most of the CLonorchis-infected soldiers (6171 were recruited from Kyongsangnam-do.

• Journal of the Korean Society of Tobacco Science
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• v.16 no.2
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• pp.97-101
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• 1994

Tobacco stalks were cut and removed from the field after harvest, and urea was treated by placing it on the cutting portions of the remaining tobacco stumps. Relative virus infectivity of the root residue(compared to the fresh root residue infected with TMV) was reduced to 14.6% in December, 1993(before overwintering) and to 8.5% in March, 1994 just before transplanting, indicating that the TMV infectivity decreased remarkably, but was preserved still in the root residue in the field soil. There was no significant difference in infectivity of remaining root tissue between the treated and untreated root residue. However, as roots with urea treatment had been extensively decayed, only about one - fifth of the initial root volume remained after overwintering. TMV occurred less (by one - third) in the urea treatment than in the control, suggesting that urea treatment effectively provented tobacco from TMV infection by reducing the inoculum potential.

• The Plant Pathology Journal
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• v.23 no.3
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• pp.212-214
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• 2007

In 2005 and 2007, a basal stem rot of Disporum smilacinum caused by Sclerotium rolfsii occurred sporadically in a herb farm at Hamyang, Korea. The symptom initiated with water-soaking lesion and progressed into stem rot and wilt of a whole plant. Severely infected plants were blighted and died eventually. White mycelial mats appeared on the lesion at early stage and a number of sclerotia were formed on the stem near the soil line. The sclerotia were globoid in shape, 1-3 mm in size and white to brown in color. The optimum temperature for the growth and sclerotia formation was 30 on PDA and the hyphal width was measured $3-8{\mu}m$. The typical clamp connections were observed in the hyphae of the fungus grown on PDA. On the basis of symptom, mycological characteristics and pathogenicity to the host plant, this fungus was identified as Sclerotium rolfsii Saccardo. This is the first report on the stem rot of D. smilacinum caused by S. rolfsii in Korea.

• Microbiology and Biotechnology Letters
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• v.22 no.6
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• pp.679-684
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• 1994

For a biological control of root-knot nematode (Meloidogyne incognita) in tomato, efficiency of Bacillus thuringiensis subsp. indiana strain TH109 (BtTH109) on the nematode control was investigated. After the mixture of strain BtTH109 and wheat bran was treated into rhizosphere of the tomato plants with nematode eggs, the stem height and root growth of plants increased. And the juveniles and eggs of nematode are not found in both roots of tomatoes and pot soil after cultured broth of the strain BtTH109 treated 4 times at 3 day-interval into rhizosphere of the infected tomatoes.