• Research in Plant Disease
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• v.17 no.3
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• pp.302-310
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• 2011

Elsinoe fawcettii is one of major pathogenic fungi which cause citrus scab diseases, resulting in fruit blemishes that reduce the economic value of fruit. By increasing interest to safe products of crops, the alternative methods of disease control is highly required. We investigated whether the 215 bacterial strains isolated from Jeju Island possess antifungal effect or suppression effect on the symptom development by Elsinoe fawcettii on citrus. Among them, three bacterial strains THJ 609-3, MRL408-3, and TRH423-3 that exhibited antifungal capacity against Elsinoe fawcettii were selected. To illustrate the disease suppression mechanism, pre-inoculation with the selected bacterial strains was carried out whether could suppress the citrus crab on the leaves. The observation with a fluorescence microscope revealed that the selected bacteria could decrease the number of fungal spores. The ratio of germ tube formation was also decreased by the selected bacterial strains at one day after fungus challenge. The strain THJ 609-3 was identified as Pseudomonas putida as a result of analyzing the internal transcript spaces of the rhizobacterial rDNA. The strains MRL 408-3 and TRH 423-3 were identified as Burkholderia gladioli. Our results may be valuable when the selected rhizobacterial strains used as the environment-friendly microbe for biological control on citrus scab caused by Elsinoe fawcettii.

• Korean Journal Plant Pathology
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• v.2 no.2
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• pp.89-95
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• 1986

The five short-chain fatty acids such as isobutyric(C-4), butyric(C-4), isovaleric(C-5), valeric(C-5) and caproic (C-6) acids obtained from the extract of common purslane showed wide antifungal spectra against spore germination and mycelial growth of the twenty five phytopathogenic fungi tested in vitro, although there were differences in antifungal potency among them. The antifungal potency of each fatty acid varied significantly against different fungi in spore germination and mycelial growth. The seventeen fungi used for spore germination test and the sixteen fungi used for mycelial growth test can be divided into three groups depending upon differences in minimal inhibitory concentration of each fatty acid for them, respectively. Caproic acid was significantly more toxic to germination than to mycelial growth of the test fungi, while the other four fatty acids did not show such a significant differences in toxicity with a few of exceptions as shown in valerie acid. The longer the chain-length of fatty acid was, the higher the antifungal potency was shown. The normal fatty acids such as butyric and valerie acid were more toxic than their isomers to spore germination and mycelial growth of the test fungi. Each fatty acid was more toxic to spore germination of obligate parasites and some of facultative parasites, and mycelial growth of facultative parasites than to spore germination and mycelial growth of saprophytes, respectively.

• 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.

• Research in Plant Disease
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• v.29 no.1
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• pp.11-22
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• 2023

Resazurin-based microtiter assay was used to evaluate the inhibitory effect of fungicides on the respiration of Colletotrichum acutatum s. lat. 20JDS8 sensitive and 20CDJ6 resistant to strobilurin fungicides. The spores of C. acutatum s. lat. 20JDS8 were inoculated into potato dextrose broth (PDB) at densities of 1x10⁴, 1x10⁵ and 1x10⁶ spores/ml, respectively. The relative fluorescence unit (RFU) of all treatments inoculated at each spore density started to rise after 12 hr of incubation, and were 1,965.5, 5,412.5, and 10,061.0, respectively, after 24 hr of incubation. To evaluate the inhibitory effect of fungicide on the respiration of the pathogen, the spores of the pathogen were inoculated into the PDB and treated with the fungicides 0, 6, 12, and 24 hr after incubation, respectively. After keeping the pathogen culturing for another 24 hr, PrestoBlue reagent was treated into the PDB culturing the pathogen. The RFU of each treatment was examined 1 hr after the reagent was treated. When dithianon, isopyrazam, pyraclostrobin, and fluazinam were treated at high concentrations in the stages of spores (immediately after inoculation [0 hr]), spore germination (after incubation for 6 hr), and hyphal growth (after incubation for 12 hr), the respiration of pathogens was inhibited by 90-100%. When the fungicides were treated after culturing the pathogen for 24 hr, the respiratory inhibitory effects were greatly reduced. With pyraclostrobin-resistant C. acutatum s. lat. 20CDJ6, azxoystrobin, trifloxystrobin and kresoxim-methyl, which have the same mode of action, had very little or no respiratory inhibitory effect in all growth stages of pathogens. Based on the above results, it was thought that the resazurin-based microtiter assay could quickly and accurately evaluate the inhibitory efficacy of the fungicides that inhibited respiration.

• Journal of Bio-Environment Control
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• v.21 no.2
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• pp.140-146
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• 2012

The commercial product "pyto-patch" prepared as nano sized silver particle less than 5 nm, has effective antifungal activity against Collectotrichum gloeosporioides, Botrytis cinerea, Sclerotinia sclerotiorum in vitro. As a fungal growth inhibiton mechanism, it can reduce spore germination rate and mycelial growth. As s promising fungicide, Phyto-patch can control anthracnose effectively. The spore of C. gloeosporioides dipped in 5 ppm phyto-patch dilute suppressed germination rate to 13.2%, and mycelial growth stopped for 15 days at 10 ppm. The spore postinoculated on 10 ppm phyto-path smeared PDA surface could not germinate for 3 days and prohibit pathogen infection effectively. In field test, the anthracnose development of 4 ppm phyto-patch treated plot was less than 7% after 21 days compaired to 40% of it in untreated plot. In heavy rainfall season, pepper anthracnose effectivly contrrolled by regular 10 ppm phytopatch spraying every 7 days. The diseased pepper fruit decreased to 5.8% compaired to 94.6% in untreated plot. During drying period, the diseased pepper fruit havested in phyto-patch treated plot was 24.2%, but pepper fruit havested in untreated plot destroyed to 100% within 3 days. The nano silver particle coated on multching textile prevented late blight of pepper effectively and disease occurance delayed about month.

• Research in Plant Disease
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• v.16 no.2
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• pp.125-128
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• 2010

Bacterial black spot disease of prune fruit (Prunus salicina cv. formosa) has outbroke around major prune production area, Gimcheon, Euiseong and Gunwi in Gyungbuk province and has caused severe economic loss. Integrons PCR primer was designed along with sample pre-incubation and nested PCR method to enhance detection sensitivity for early detection of bacteria in fields. Designed integrons PCR primer successfully detected Xanthomonas arboricola pv. pruni from field collected samples, fruit, leaf, branch and even in raindrop collected from prune orchard. Pre-incubation along with nested PCR enhanced sensitivity to detect X. arboricola pv. pruni from seemingly healthy looking, symptomless branches. Designed integrons PCR can be used in prune nursery fields and in plant quarantine practice for the detection of X. arboricola pv. pruni.

• Proceedings of the Korean Society of Life Science Conference
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• 2002.03a
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• pp.109-109
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• 2002

• Research in Plant Disease
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• v.17 no.3
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• pp.391-395
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• 2011

The presence of Pleochaeta shiraiana associated with powdery mildew of Celtis sinensis in Korea is dubious, mainly due to incomplete records of earlier workers. To confirm the occurrence of the powdery mildew and the identity of the causal fungus, morphological characteristics of the anamorph and teleomorph from nine samples deposited in KUS (Herbarium in Korea University) were examined by light microscopy. Identification of the fungus was supported by comparing four ITS sequences from Korean samples with two Japanese data. This is the first confirmed report of the powdery mildew associated with P. shiraiana in Korea.

• Research in Plant Disease
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• v.6 no.1
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• pp.36-38
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• 2000

A disease of Kalopanax pictus was found in Taebaec of Kang-won province. Korea, 1998. Typical symptoms were dark green to brown lesions appeared on the leaf and the stem canker. Many spores appeared on the lesions under humid conditions. A Botrytis species was consistently isolated from the infected plants. Conidia were obvoid to ellipsoid, 1-celled, hyaline or pale brown. The conidia were about 6-12${\times}$4-8$\mu\textrm{m}$ under scanning electron microscope, many micro-projections appeared on the surface of conidia. the isolated fungus infected heathy Kalopanax pictus. symptoms in inoculated plants were similar to those of originally diseased plants. The causal agent was identified as Botrytis cinerea. Gray mold of Kalopanax pictus was proposed to name this disease.

• Research in Plant Disease
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• v.6 no.1
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• pp.33-35
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• 2000

A disease of Cyclamen persicum was found in Kangnung of Kang-won prefecture, Korea, 1999. Typical symptoms were dark green to brown lesions appeared on petals and leaves. Many spores appeared on the lesions under humid conditions. A Botrytis species was consistently isolated from the infected plant. Conidia were obvoid to ellipsoid, 1-celled, hyaline or pale brown. The conidia were about 0.9-16.0$\times$6.0-10.4㎛(mean, 1.27$\times$7.8㎛) under scanning electron microscope, many micro-projections appeared on the surface of conidia. The isolated fungus infected heathy Cyclamen persicu. The causal agent was identified as Botrytis cinerea. Gray mold of Cyclamen persicum was proposed to name this disease.