• The Plant Pathology Journal
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• v.17 no.5
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• pp.311-314
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• 2001

Phytophthora root rot of lettuce, which has not been reported in Korea before, occurred severely in liquid hydroponic culture. The disease occurred in all seasons and was most severe in summer from June to August, showing over 90% infection rate in some farms. A total of 51 isolates collected from various farms were all identified as Phytophthora drechsleri. The fungus showed strong pathogenicity to lettuce and Chinese cabbage, moderate pathogenicity to cucurbits and tomato, and weak pathogenicity to pepper. However, the fungus was not pathogenic to other leafy vegetables namely: chicory, kale, endive, garland chrysanthemum, spinach beet, and perilla. Among 10 species of Phytophtora inoculated to lettuce, only P. drechsleri and P. cryptogea were found pathogenic.

• Research in Plant Disease
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• v.10 no.2
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• pp.100-104
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• 2004

Two species of Phytophthora were isolated from a leaf blight disease found on castor bean plants growing at a residential area of Hwanggeum-dong in Daegu city. One species was producing conspicuously papillate, noncaducous, ovoid to obpyriform sporangia, 31.2-58.5 ${\times}$ 25.4-44.1 ${\mu}{\textrm}{m}$ in range with an average of 46.4 $\pm$ 6.5 ${\times}$ 35.9 $\pm$ 4.7 ${\mu}{\textrm}{m}$ on simple sympodial sporangiophores, was heterothallic with oogonia globose, 22.5-35.0 ${\mu}{\textrm}{m}$ with an average of 30 $\pm$ 3.3 ${\mu}{\textrm}{m}$ in diameter, oospores plerotic, 18.8-30.0 ${\mu}{\textrm}{m}$ in range averaging 25.4 $\pm$ 2.8 ${\mu}{\textrm}{m}$, and with antheridia amphigynous. This species was identified as P. nicotianae Breda de Haan. The other species produced papillate, caducous, ovoid to ellipsoid sporangia with pedicel, 21.5-54.6 ${\times}$ 17.6-34.3 ${\mu}{\textrm}{m}$ in range with an average of 41.7 $\pm$ 7.1 ${\times}$ 28.4 $\pm$ 4.0 ${\mu}{\textrm}{m}$, and was heterothallic with oogonia globose, 21.3-26.8 ${\mu}{\textrm}{m}$ with an average of 23.0 $\pm$ 1.6 ${\mu}{\textrm}{m}$ in diameter, oospores plerotic, 17.5-23.8 ${\mu}{\textrm}{m}$ in range averaging 20.2 $\pm$ 1.8 ${\mu}{\textrm}{m}$, and with antheridia amphigynous. This species was identified as P. palmivora (Butler) Butler. Both species produced chlamydospores. Pathogenicity of the 2 speices was confirmed by foliar inoculation of castor bean seedlings. Both species have been reported to infect castor bean plants in a few foreign countries but it is the first that a disease of castor bean plants caused by either or both of the species was found in Korea.

• Mycobiology
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• v.28 no.4
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• pp.193-196
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• 2000

Thirty-eight species in addition to 2 varieties (3 unidentified) of zoosporic organisms belonging to 14 genera of Oomycetes and 3 genera of Chytridiomycetes were recovered from 50 soil samples randomly collected from different localities in the western region of Saudi Arabia. Allomyces and Dictyuchus have the highest frequency of occurrence while Achlya, Aqualinderella, Saproleginia and Phytophthora were of moderate occurrence, The remaining genera were less frequent. Seven species and two varieties were new records to Saudi Arabia, which are Achlya oblongata, Allomyces javancius var. allomorphus, Aphanomyces stellatus, Blastoccladia gracile, Dictyuchus magnusii, Olpidiopsis Saproleginia var. levis, Olpidium species, Phytophthora megasperma, and Saproleginia turfosa. Water and organic matter contents of soil samples are considered as major factors influencing the prevalence and occurrence of zoosporic organisms.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2010.05a
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• pp.6-6
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• 2010

Bacteria of the Bacillus sp. are well known to possess antagonistic activity against numerous plant pathogens. In the present study, 11 Bacillus sp. were isolated from the brackish environment and assayed for antagonistic activity under in vitro and in vivo conditions. Among the 11 isolates tested, 9 isolates effectively inhibited the growth of various plant pathogens, namely Phytophthora capsici, Phytophthora citropthora, Phytophthora citricola, Phytophthora sojae, Colletotricum coccodes, Colletotricum gloeosporioides, Colletotricum acutatum, Rhizoctonia solani, Fusarium solani, Fusarium graminearum, Pyricularia sp. and Monilina sp. The effective isolates were further screened for Phytophthora blight suppression in Capsicum annuum L. under green house conditions. The isolate SB10 exhibited the maximum (72.2%) reduction in disease severity. The antifungal compounds from the isolate were isolated and characterized. The isolated compounds exhibited high thermo stability ($100^{\circ}C$ for 30 min). Matrix-Assisted Laser Desorption Ionization-Time of Flight investigation of the antifungal compounds revealed three lipopeptide complexes, the surfactins, the iturins, and the fengycins.

• Korean journal of applied entomology
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• v.21 no.4 s.53
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• pp.211-215
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• 1982

Incidences of Phytophthora blight in plant of sesame (Sesamum indicum L.) were observed in southern sesame production areas, Gochang of Jeonbug, Yeonggwang of Jeonnam, Jinyang of Gyeongnam and Dalseong of Gyeongbug province where disease survy was conducted from July 29 to August 1, 1981. The rate of disease incidence ranged from none to $61\%$ depending upon the field observed. The causal species of the Phytophthora was identified as P. nicotianae var. parasitica (Dastur) Waterhouse based on specific pathogenicity to sesame and morphological characteristics of sporangia. Diseased plants of sesame generally showed dark discoloration on the stem leading to plant death.

• Microbiology and Biotechnology Letters
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• v.34 no.2
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• pp.101-108
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• 2006

YNB54 strain which shows inhibitory activities specific to the plant pathogenic Phytophthora sp. on potato dextrose agar medium was screened among lots of strains isolated from Korean soils. To identify taxonomy of the Phytophthora specific antagonistic bacteria YNB54, 165 rDNA sequence, MIDI fatty acid composition, DNA-DNA hybridization, GC content, and commercial multitest systems such as API 20E and Biolog GN were performed. Results of commercial kits including lots of biochemical and physiological reactions showed that this strain was closely related to taxa including Enterobacter cloacae and Enterobacter cancerogenus species than other genera(Citerobacter Klebsiella, Leclercia). Also, analysis of its MIDI, G+C contents, and DNA-DNA hybridization suggests that this strain was more similiar to the Genus Enterobacter than other genera (Citerobacter Klebsiella, Leclercia). This strain was potentially identified as Enterobacter sp. by these results. But our 16S ribosomal DNA sequences (rDNA) analysis confirmed that it was more closely related to the cluster of Citerobacter freundii ATCC 29935 than any other Enterobacter species. In the absence of defined phylogenetic critia for delineating genera, the results observed with Citrobacter and Enterobacter species suggest that further studies are needed to clarify their relationships. This investigation demonstrates that YNB54 strain is genetically diverse and potentially more taxonomically complex than hitherto realized. Further study is necessary to confirm their taxonomic positions.

• The Plant Pathology Journal
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• v.17 no.4
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• pp.227-230
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• 2001

Bioassay techniques using young leaves and roots were developed to screen resistance of Atractylis spp. against Phytophthora drechsleri. Among 638 plants collected from various regions of Korea from 1994 to 1996, 67 were pre-screened in fields naturally infested with P. drechsleri, which is the causal pathogen of rhizome rot of Atractylis. Among the pre-screened sources, 18 (ca. 26.8%) were highly resistant to the pathogen in leaf inoculation. In the root inoculation test, abundant sporangia were formed in susceptible plant roots, while only a few or no sporangia were produced on the roots which were found resistant in the leaf inoculation test. Among the selected resistant plants, A. japonica 96066 and 96104 were used to cross with another species, A. macrocephala 96362 that showed high yield with good quality of rhizome but susceptible to the pathogen. The F$_1$hybrids designated as HA03 turned out to be resistant to the pathogen, indicating that resistant gene(s) was inherited. Among intra-species hybrids of A. japonica, HA07 and HA09 were resistant to the pathogen in leaf inoculation and moderate in root inoculation. However, HA08 was susceptible in both inoculation tests. This result suggests that the parent material might be genetically heterogeneous. Further genetic study should be carried out to verify this phenomenon.

• Journal of Microbiology and Biotechnology
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• v.15 no.2
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• pp.227-233
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• 2005

Fungal strain CGF was isolated from the soil of ChungNam Province, South Korea. Based on the 28S rDNA sequence analysis and the sequence of the internal transcribed spacer (ITS) region of ribosomal DNA, together with morphological and cultural characteristics, this strain was identified as Aspergillus sclerotiorum and renamed Aspergillus sclerotiorum CGF. This is the first strain of Aspergillus sclerotiorum identified in Korea. When the antifungal activity of A. sclerotiorum CGF was evaluated, among the phytopathogenic fungi, mycelial growth of only Phytophthora species was inhibited. Oermination of P. capsid zoospore was also inhibited. The bioactive compound of A. sclerotiorum CGF was highly thermo- and pH-stable.

• Journal of Environmental Health Sciences
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• v.38 no.2
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• pp.159-165
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• 2012

Objectives: This experiment was carried out to elucidate the effect of discharged water on the disinfection of $Phytophthora$ $capsici$ and evaluate the water characteristics. Methods: The dielectric barrier discharges (DBD) plasma reactor system used in this study consisted of a plasma component [discharge, ground electrode and quartz dielectric tube], high voltage source, and air supply. The effects of water characteristics such as pH, ORP and conductivity and the disinfection effect of discharged water were investigated. Results: Experimental results showed that in the process of discharge, the pH decreased, whereas ORP and electric conductivity increased. When the discharge time was 30 min, $Phytophthora$ $capsici$ of 2.94 log was disinfected within 300 seconds. Disinfection performance of stored discharged water was maintained for three days; however the disinfection effect vanished after five days. When $Phytophthora$ $capsici$ was injected into the discharged water, the disinfection effect decreased after two days. Conclusions: It is considered that the main disinfection parameters of the discharged water were chemically active species such as $H_2O_2$ and $O_3$ and high ORP.

• The Korean Journal of Mycology
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• v.17 no.1
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• pp.39-47
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• 1989

Among 100 species in 54 families of plants tested, leaf extracts from Allium cepa, Allium sativum, Malussieboldii, Reynoutria japonia and Rheum coreanum were inhibitory on mycelium growth of phytophthora spp.. Especially, Allium sativum and Malus sieboldii were strongly inhibitory. Allium sativum, Malussieboldii and Rhem coreanum were strongly inhibitory on zoosporangium germination of P. capsici. Malus sieboldii only were strongly inhibitory on zoosporangium germination of P. nicotiana and P. infestans.And Malus sieboldii were strongly effected on disease control of these pathogens. These results indicate the possibility of finding antagonistic plants in the nature for the control of certain pathogens in soil.