• Title/Summary/Keyword: P. ultimum

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Virulence and Relative Density of Three Root Rotting Organisms; Pythium ultimum, Pythium echinocarpum and Rhizoctonia solani in Alpine Soils in Chinese Cabbage (고냉지 배추 재배지역 토양에서 배추에 뿌리 썩음을 일으키는 Pythium ultimum, Pythium echinocarpum, Rhizoctonia solani균의 병원력 및 토양내 상대밀도)

  • Kim, Choong-Hoe;Cho, Won-Dae
    • Korean journal of applied entomology
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    • v.25 no.3 s.68
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    • pp.183-189
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    • 1986
  • Fifty three diseased root samples of Chinese cabbage and 22 soil samples were taken from six alpine areas in Kangwon province to examine the organisms causing root rot of Chinese cabbage. Among thirteen microorganisms detected from diseased roots samples, Pythium ultimum, Pythium echinocarpum and Rhizoctonia solani were detected frequently and were pathogenic to Chinese cabbage. Five to 100% of young Chinese cabbage plants grown in the sample soils taken from alpine cabbage fields were infected either alone or together with P. ultimum, P. echinocarpum and R. solani, depending upon the or gin of sample soils. When relative density of the three organsims in the sample soils was estimated based on the infection frequency on the plants grown in those sample soils, P. ultimum was prevalent only in Chahang-i-li area. P. echinocarpum was prevalent in Yongsan-il-li, Hoengwe-li, and Munmaek areas. R. solani was solely found in Maebongsan area where both P. ultimum and P. echinocarpum were not detected. In the three areas where both P. ultimum and P. echinocarpum were present, density of P. echinocarpum was generally greater than that of P. ultimum. Seedlings of thirty major Chinese cabbage varieties were inoculated independently with the three organisms in the greenhouse. Six varieties were resistant to P. ultimum. Three and two varieties were moderately resistant to P. ultimum and P. echinocarpum, respectively. All varieties were highly susceptible to R. solani.

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Screening for Antifungal Medicinal Plants Controlling the Soil Borne Pathogen, Pythium ultimum (토양병원균(土壤病原菌) Pythium ultimum 방제(防除)를 위한 항균성(抗菌性) 약용식물(藥用植物)의 탐색)

  • Paik, Su-Bong;Oh, Yeon-Sun
    • The Korean Journal of Mycology
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    • v.18 no.2
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    • pp.102-108
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    • 1990
  • In order to find out the effect of medicinal plant extracts on germination of zoosporan-gium and mycelium growth of Pythium ultimum, this study was carried out. Among 28 species in 16 families of plants tested, plant extracts from 9 species were strongly inhibitory to zoosporan-gium germination of P. ultimum. Plant extracts from 3 species were strongly inhibitory to mycellium growth of P. ultimum. Especially, Paeonia suffruticosa was strongly inhibitory. P. suffruticosa was shown a strong control effect on damping-off of sesame by P. ultimum sesame, but no effect on cucumber. Seed germination of sesame and cucumber was shown phyto-alexin by extract of Phytolacca esculenta.

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Effect of Water Potential on Mycelial Growth and Sporangial Formation by Pythium spp. (Water Potential이 Pythium속(屬) 균(菌)의 균사(菌絲) 신장(伸長)과 Sporangia 형성(形成)에 미치는 효과(效果))

  • Sung, Jae-Mo
    • The Korean Journal of Mycology
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    • v.11 no.3
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    • pp.105-108
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    • 1983
  • The mycelial growth of Pythium graminicola, P. ultimum, P. rostratum was best at -3 osmotic potential. P. monospermum was best grown at -8 bars osmotic potential. Mycelial growth by Pythium spp. was prevented at -42 bars for P. graminicola, P. ultimum and P. monospermum. Sporangial formation by P. graminicola and P. ultimum was influenced by water potential in much the same way as mycelial growth: -3 bars was maximum and -42 bars or below was minimal. Pythium spp. tested was grown faster on PDA than other media including oat meal agar. P. ultimum was best grown on any media among Pythium spp. tested.

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Effect of Inoculum Concentration of Rhizoctonia solani and Pythium ultimum Causing Damping-off of Pepper and Cucumber on the Efficacy of the Mixture of Etridiazole and Thiophanate-methyl (Rhizoctonia solani와 Pythium ultimum의 접종 농도가 etridiazole과 thiophanate-methyl 합제의 모잘록병 방제 효과에 미치는 영향)

  • Kim, Hyung-Jo;Jang, Ho-Sun;Lee, Soo-Min;Kim, Joo-Hyung;Shin, Jin-Ho;Kim, Heung-Tae
    • The Korean Journal of Pesticide Science
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    • v.14 no.1
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    • pp.65-71
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    • 2010
  • This study was performed to investigate the inhibiting activity of etridiazole and thiophanate-mthyl on mycelial growth of Rhizoctonia solani and Pythium ultimum and the effect of inoculum density of each pathogen on the control efficacy of the mixture of etridiazole and thiophanate-methyl in a seedling assay test. In mycelial growth inhibition test, $EC_{50}$ values of etridiazole and thiophanate-methyl against R. solani were 15.87 and 9.34 ${\mu}g\;mL^{-1}$, while those were 0.2 and more than $500\;{\mu}g\;mL^{-1}$ against P. ultimum, respectively. Controlling activity of the mixture of etridiazole and thiophanate-methyl against damping-off of pepper and cucumber, caused by R. solani and P. ultimum was tested in a greenhouse. With the inoculation of R. solani, disease incidences of seedling in pepper were 73% and 95% at 0.5% and 1.0% of inoculum concentration, while in cucumber those were 55% and 62% at 1.0% and 2.0%. When P. ultimum was inoculated into soil by 2.0% of inoculum concentration, those in pepper and cucumber were 66.7% and 96.8%, respectively. The efficacy of the mixture was somehow affected by the concentration of R. solani. While each control value of the mixture was 94.4% and 90.7% in pepper and cucumber at low inoculum concentration (0.05%), the efficacy of the fungicide decreased in pepper and cucumber by 70.7% and 72.9% at high concentration of R. solani (0.1% in pepper and 0.5% in cucumber). However, the control value of the mixture was 100% in pepper and cucumber, irrespective of the inoculum concentration of P. ultimum, however, the increase of inoculum concentration in soil did not result in the decrease of the fungicide efficacy.

Biological Control of Pythium Root Rot by Radiation Induced Mutant, Bacillus lentimorbus WJ5a17 (방사선유도 돌연변이체 Bacillus lentimorbus WJ5a17에 의한 Pythium Root rot의 방제)

  • 이영근;김재성;장병일;장유신;이호용
    • Korean Journal of Environmental Biology
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    • v.21 no.3
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    • pp.276-285
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    • 2003
  • To control pythium root rot, Bacillus lentimorbus WJ5a17 with high anti-fungal activity against Pythium ultimum was induced from B. lentimorbus WJ5 by gamma radiation ($^{60}Co$). The biocontrollers of FWJ5 and FWJ5a17 were formulated ($1.0\times 10^{11}$) with B. lentimorbus WJ5 and WJ5a17, respectively, The population density of FWJ5 and FWJ5a17 maintained highly up to $1.0\times 10^{9}$ CFU $g^{-1}$ in nursery and field soils until 30 days after treatment. P. ultimum spores germination were inhibited 71.0% and 81.4% by FWJ5 and FWJ5a17, respectively. Pythium root rot of yea pepper, Chinese cabbage and radish were significantly (p < 0.05) controled by one time treatment of FWJ5 and FWJ5a17.

Pythium spp. Isolated from Turfgrasses at Golf Courses in Korea (우리나라 골프장 잔디에서 분리한 Pythium spp.)

  • Kim, Jin-Won;Park, Eun-Woo
    • The Korean Journal of Mycology
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    • v.25 no.4 s.83
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    • pp.276-290
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    • 1997
  • Eleven species of Pythium were identified from 125 isolates collected from leaf blight lesions on creeping bentgrass (Agrostis palustris Huds.), Kentucky bluegrass (Poa pratensis L.), and zoysiagrasses (Zoysia japonica Steud., and Z. matrella (L.) Merr.) at 35 golf courses in Korea in $1990{\sim}1996$. The identified species included P. aphanidermatum, P. arrhenomanes, P. catenulatum, P. graminicola, P. myriotylum, P. oligandrum, P. periplocum, P. rostratum, P. torulosum, P. ultimum var. ultimum, and P. vanterpoolii. Mycological characteristics of sporangia, oogonia, antheridia, and oospores observed on the sucrose-asparagine bentgrass leaf culture medium were described for each species. Of the species, P. arrhenomanes, P. catenulatum, P. gmminicola, P. oligandrum, P. periplocum, P. rostratum, P. torulosum and P. vanterpoolii were reported for the first time in Korea. P. myriotylum, P. rostratum, P. torulosum and P. vanterpoolii showed characteristic colony patterns on the potato-carrot agar medium, which can be used as criteria for species identification of Pythium.

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Synthesis and Fungicidal Activities of Substituted Phenyl Hydrazono-3-Methyl-1, 2-Isoxazol-5-One Derivatives. (치환 Phenyl Hydrazono-3-Methyl-1, 2-Isoxazol-5-One 유도체의 합성과 살균활성)

  • Park, Kwang-Wook;Keum, Young-Su;Park, Chang-Kyu
    • Korean Journal of Environmental Agriculture
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    • v.15 no.2
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    • pp.239-245
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    • 1996
  • Fungicidal activity has been examined for a series of substituted phenylhydrazono-3-methyl-1,2-isoxazol-5-one against plant pathogenic fungi. 3-methyl isoxazol-5-one was obtained from ethyl acetoacetate and hydroxyl amine. Final products were prepared by aromatic diazo coupling with 3-methyl isoxazol-5-one. Fungicidal activities against Rhizoctonia solani, Colletotrichum gloeosporioides, Cladosporium cucumerinum, Pythium ultimum were tested and Pythium ultimum were tested and Pythium ultimum was selected for quantitative measurement of activity. Methyl, halogen, nitro derivatives possessed high fungicidal activity at p-, o-, p- position, respectively. Methyl, halogen derivatives were much more active than alkoxy, nitro derivatives and the order of activity of halogen derivatives was F > Cl > I. This result implied that the activity was related to the molecular volume of substitutents.

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Production of the Antifungal Compound Phenylacetic Acid by Antagonistic Bacterium Pseudomonas sp.

  • Kang, Jae Gon;Kim, Sun Tae;Kang, Kyu Young
    • Journal of Applied Biological Chemistry
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    • v.42 no.4
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    • pp.197-201
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    • 1999
  • Antagonistic bacteria active against phytopathogenic fungi, Phytophthora capsici, Pythium ultimum, Rhizoctonia solani, Botrytis cinerea, and Fusarium oxysporum were isolated from greenhouse soils. An antifungal compound was extracted by ethyl acetate from acidified culture filtrate and purified through column chromatography and thin layer chromatography. Activity-guided bioassay was followed throughout the purification steps using Pythium ultimum as a test organism. The purified antifungal compound was identified as phenylacetic acid (PAA) based on the data obtained from IR, EI/MS, $^1H-NMR$, and $^{13}C-NMR$. Two different isolates, which had vast differences in differential characteristics except 16S rDNA sequence homology, produced the same compound, phenylacetic acid. $ED_{50}$ values of the phenylacetic acid against P. ultimum, P. capsici, R. solani, B. cinerea, and F. oxysporum were 45, 21, 318, 360, and 226 ppm, respectively.

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Effect of Organic Amendments on Efficacy of Biological Control of Seedling Damping-off of Cucumber with Several Microbial Products (유기물 첨가가 오이 모잘록병에 대한 미생물 제제의 생물학적 방제 효과 증진에 미치는 영향)

  • Lee, Jong-Moon;Do, Eun-Soo;Baik, Su-Bong;Chun, Se-Chul
    • The Korean Journal of Mycology
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    • v.31 no.1
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    • pp.44-49
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    • 2003
  • Several microbial biocontrol products (Greenbiotech Co., Paju, Korea), Green-all T (Trichoderma harzianum), Green-all S(Bacillus sp.) and Green-all G (Streptomyces sp.) were supplemented with organic amendments such as sawdusts and rice hulls to study on efficacy of biological control of seeding damping-off of cucumber caused by Pythium ultimum. Sawdusts amended into potato dextrose agar alone could inhibit in vitro mycelial growth of P. ultimum. All there microbial products of Green-all T, Green-all G and Green-all S significantly reduced seeding damping-off (LSD, P=0.05). However, several amendments such as sawdusts and rice hulls into Green-all T and Green-all S products did not increase efficacy of biological control compared to non-amended treatment. In contrast, supplements of aminodoctor containing several amino acids (Greenbiotech Co., Korea) into Green-all G product significantly increased efficacy of biological control of seeding damping-off, resulting in from 42% to 2% disease incidence in relation to seedling emergence (LSD, P=0.05). Also, amendment of sawdusts into Tricoderma product significantly increased efficacy of biological control as disease index of 5.0 compared to non-amended control of 56.0 in Green-all T product alone. This indicates that organic amendments could increase efficacy of biological control of cucumber seedling damping-off.

Identification and Pathogenicity of Pythium spp. Associated with Seedling Damping Off of Rice (벼 모 마름병(病)을 일으키는 Pythium속(屬) 균(菌)과 병원성(病原性))

  • Sung, Jae-Mo;Jin, Kyoung-Sik;Lee, Seung-Chan;Park, Jong-Seung
    • The Korean Journal of Mycology
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    • v.11 no.1
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    • pp.27-32
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    • 1983
  • Five species of the genus Pythium were identified from 91 isolates which were collected from rice seedlings in machine transplanting nursery boxes and paddy fields in Korea. They included P. graminicola complex, P. monospermum complex, P. rostratum complex, and P. ultimum complex. The most frequently found species of the genus Pythium was P. graminicola complex followed by P. monospermum complex. Rice seed germinability was greatly decreased by being infested with P. graminicola complex at nursery box. P. graminicola complex was the most virulent in terms of prohibiting germinations and stunting plants in nursery boxes.

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