• Title, Summary, Keyword: Pseudoperonospora cubensis

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Occurrence of Downy Mildew on Watermelon (Citrullus lanatus) Caused by Pseudoperonospora cubensis on Seedling Nursery in Korea (육묘상에서 Pseudoperonospora cubensis에 의한 수박 노균병 발생)

  • Kwon Jin-Hyeuk;Park Chang-Seuk
    • Research in Plant Disease
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    • v.12 no.2
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    • pp.125-128
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    • 2006
  • Downy mildew caused by Pseudoperonospora cubensis (Berkeley & Curtis) occurred on the cotyledon of gourd (Lagenaria leucantha cv. Sambokkkul) and scion of watermelon (cv. FR couple) in commercial nursery around Jinju city, Gyeongnam province in Korea in 2005 and 2006. The disease symptoms usually started with water-soaking lesions on cotyledon and then the infected leaves became withered and eventually died. The sporangia of the pathogen were one-celled, ovoid to ellipsoid in shape, pale grayish in color, and $20{\sim}32{\times}14{\sim}18{\mu}m$ in size. Sporangiophores were errect, branched, and $140{\sim}380{\times}4{\sim}8{\mu}m$ in size. Pathogenicity of the causal organism was proved according to artificial inoculations. Although the virulence of the causal fungus on the host plants was not strong, it produced typical symptoms. The causal organism was identified as Pseudoperonospora cubensis (Berkeley & Curtis) based on the mycological characteristics of the fungus and pathogenicity. This is the first report on downy mildew of watermelon caused by P. cubensis in Korea.

Pseudoperonospora urticae Occurring on Urtica angustifolia in Korea

  • Choi, Young-Joon;Lee, Hyang Burm;Shin, Hyeon-Dong
    • The Korean Journal of Mycology
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    • v.45 no.2
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    • pp.160-166
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    • 2017
  • The genus Pseudoperonospora (Peronosporales, Oomycota) comprises six accepted species, including Ps. cubensis, which causes downy mildew on many economically important cucurbitaceous crops, and Ps. humuli, which occurs on hops. During a survey of downy mildew flora in Korea, a previously unreported species of Pseudoperonospora was found on Urtica angustifolia. Based on molecular phylogenetic and morphological analyses, the causal agent was identified as Pseudoperonospora urticae. This is the first report of Pseudoperonospora urticae occurring on Urtica angustifolia in Korea.

Fungichromin Production by Streptomyces padanus PMS-702 for Controlling Cucumber Downy Mildew

  • Fan, Ya-Ting;Chung, Kuang-Ren;Huang, Jenn-Wen
    • The Plant Pathology Journal
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    • v.35 no.4
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    • pp.341-350
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    • 2019
  • Streptomyces padanus PMS-702 strain produces a polyene macrolide antibiotic fungichromin and displays antagonistic activities against many phytopathogenic fungi. In the present study, experimental formulations were assessed to improve the production of fungichromin, the efficacy of PMS-702 on the suppression of sporangial germination, and the reduction of cucumber downy mildew caused by Pseudoperonospora cubensis. PMS-702 strain cultured in a soybean meal-glucose (SMG) medium led to low levels of fungichromin accumulation and sporangial germination suppression. Increasing medium compositions and adding plant oils (noticeably coconut oil) in SMG significantly increased fungichromin production from 68 to $1,999.6{\mu}g/ml$. Microscopic examination reveals that the resultant suspensions significantly reduced sporangial germination and caused cytoplasmic aggregation. Greenhouse trials reveal that the application of PMS-702 cultural suspensions reduced downy mildew severity considerably. The addition of Tween 80 into the synthetic medium while culturing PMS-702 further increased the suppressive efficacy of downy mildew severity, particularly when applied at 24 h before inoculation or co-applied with inoculum. Fungichromin at $50{\mu}g/ml$ induced phytotoxicity showing minor necrosis surrounded with light yellowish halos on cucumber leaves. The concentration that leads to 90% inhibition (IC90) of sporangial germination was estimated to be around $10{\mu}g/ml$. The results provide a strong possibility of using the S. padanus PMS-702 strain as a biocontrol agent to control other plant pathogens.

Effects of Fungicide Control of Downy Mildew (Pseudoperonospora cubensis) on Yield and Disease Management of Ridge Gourd (Luffa acutangula)

  • Deadman, M.L.;Kagadi, S.R.;Pawar, D.R.;Gadre, U.A.
    • The Plant Pathology Journal
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    • v.18 no.3
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    • pp.147-151
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    • 2002
  • Seven fungicides were compared for the control of downy mildew on midge gourd. All treatments had significantly lower rates of disease progress curves and disease severity levels than that of the control. The highest yields were obtained from crops treated with metalaxyl + mancozeb, fosetyl-Al, and chlorothalonil. These treatments also proved to be the most economical considering the treatment costs.

Occurrence and Control of Downy Mildew of Netted Melon in Chonnam Province (전남지역 온실멜론의 노균병 발생 및 방제 실태)

  • 고영진;안미연;서정규
    • Korean Journal Plant Pathology
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    • v.12 no.4
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    • pp.459-462
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    • 1996
  • 예년과는 달리 6월 중순부터 7월 중순까지 낮은 기온과 잦은 강우로 인한 음습한 날씨가 지속되었던 전남지방의 온실멜론에서 노균병이 격발하였다. 올해 전남지역에서 심하게 발생한 노균병의 병징은 다각형의 모무늬 외에도 불규칙한 대형의 부정형 무늬를 형성하였으며, 이러한 급성형 병징들은 주로 개화기 무렵 아랫잎에서부터 나타나기 시작하여 병이 진전됨에 따라 윗쪽으로 진전되었고 병반이 뭉쳐져 잎을 급속하게 고사시켰다. 표본 조사한 12개 농가의 시설 하우스에서 재배되고 있는 온실멜론의 노균병 이병엽율은 1%에서 100%까지 다양하였으며 수확을 전혀 못한 농가도 있었다. 각 농가에서는 노균병의 방제를 위하여 발병초기부터 농가당 최소 3회에서 최고 8회까지 살균제를 살포하는 방제 노력을 기울였으나 정확한 노균병 진단의 실패와 적정 약제 선정의 실패로 혼선을 빚어 방제효과는 높지 않았으며, 농약의 남용과 오용이 병방제에서 심각한 문제점으로 드러났다.

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Control of downey mildew occurred on cucumber cultivated under plastic film house condition by optimal application of chemical and installation of ventilation fan (환기조절 및 약제적기살포에 의한 비닐하우스재배 오이에 발생하는 노균병 방제)

  • Kim, Yong-Ki;Ryu, Jae-Dang;Ryu, Jae-Gee;Lee, Sang-Yeob;Shim, Hong-Sik
    • The Korean Journal of Pesticide Science
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    • v.7 no.3
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    • pp.223-227
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    • 2003
  • Survey on plant diseases occurring on cucumber cultivated in plastic film house of experimental farm in Suwon was conducted. Through the survey, occurrence of damping-off, downey mildew, powdery mildew and Fusarium wilt was observed. Especially downey mildew caused by Pseudoperonospora cubensis was the most severe foliar disease of cucumber. To control the disease effectively, effects of installation of ventilation fan and optimal spray timing of a chemical, dimethomorph+copper oxychloride WP, were investigated. Two ventilation fans installed at the front and at the back of plastic film house reduced air relative humidity by about 6.4% and downey mildew incidence by 55.7%. Downey mildew incidence on cucumber from untreated chemicals plot in plastic film house installed with ventilation fan was on a equal level with that from treated chemicals plot with three times application of dimethomorph+copper oxychloride WP in plastic film house without ventilation fan. Meanwhile in order to select optimal chemical application time, dimethomorth+copper oxychloride WP was treated three times at 7 days-interval from three days before the disease occurred, right after the disease occurred, and two days after the disease occurred, respectively. The result showed that dimethomorth+copper oxychloride WP applied to cucumber leaves and stems from three days prior to, right after, two days after occurrence of downey mildew reduced downey mildew incidence by 72.9, 61.8, and 23.7%, respectively. The above results showed that regulation of environmental factors like air relative humidity and preventive application of chemicals should be considered to establish control strategy to downey mildew.

In Vivo Antifungal Activities of Surfactants against Tomato Late Blight, Red Pepper Blight, and Cucumber Downy Mildew (계면활성제를 이용한 역병과 오이 노균병 방제)

  • Yu, Ju-Hyun;Jang, Kyoung-Soo;Kim, Heung-Tae;Kim, Jin-Cheol;Cho, Kwang-Yun;Choi, Gyung-Ja
    • Applied Biological Chemistry
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    • v.47 no.3
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    • pp.339-343
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    • 2004
  • Anionic surfactants such as sodium dioctyl sulfosuccinate (SDSS) and sodium dodecylbenzene sulfonate (NaDBS) and a nonionic surfactant, polyoxyethylene oleyl ether (OE-7) were tested for their protective, curative, and persistent activities on tomato late blight (TLB, Phytophthora infestans), red pepper blight (RPB, P. capsici), and cucumber downy mildew (CDM, Pseudoperonospora cubensis). They exhibited a strong protective activity on TLB, RPB, and CDM. Among them, $NaDBS\;(500\;{\mu}g/ml)$ showed the most in vivo antifungal activities(1-day protective activity) with control values of 99%, 100%, and 85% against TLB, RPB, and CDM, respectively. However, the three surfactants represented a weak disease controlling efficacy on TLB, RPD, and CDM in a 1-day curative application. SDSS and NaDBS exhibited a good persistent activities on TLB and RPB. Especially, NaDBS, at $500\;{\mu}g/ml$, showed control values of more than 88% on TLB and RPB in a 7-day protective application. The results indicate SDSS and NaDBS have a potential for the control of TLB, RPB, and CDM in the fields.

Improvement in Fungicidal Activity of Ethaboxam by a Non-ionic Surfactant, Polyoxyethylene Cetyl Ether

  • Shin Kwang-Hoon;Kim Dal-Soo;Chun Sam-Jae;Park Eun-Woo
    • The Plant Pathology Journal
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    • v.22 no.3
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    • pp.303-308
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    • 2006
  • Ethaboxam is a fungicide controlling plant diseases caused by Oomycetes. Efforts were made to improve its fungicidal activity applying formulation technology. Fungicidal activity of ethaboxam against cucumber downy mildew caused by Pseudoperonospora cubensis was improved by incorporating polyoxyethylene cetyl ether (PCE) in a wettable powder formulation. It was found that the optimum combination ratio of PCE and ethaboxam was 3:1, and a tank-mix of $150{\mu}g/ml$ of ethaboxam and $450{\mu}g/ml$ of PCE would be as good as the standard 25 % WP formulation diluted to $250{\mu}g/ml$ ethaboxam without PCE in controlling cucumber downy mildew. Based on this results, a wettable powder (WP) co-formulation containing 15% of ethaboxam and 45% of PCE was developed in this study, and tested for its performance in the fields. This co-formulation showed significant improvement in persistence of fungicidal activity and curative efficacy of ethaboxam against cucumber downy mildew. The improved control efficacy was also confirmed for control of grape downy mildew caused by Plasmopara viticola and potato late blight caused by Phytophthora infestans in the field tests.

Field Performance of a New Fungicide Ethaboxam Against Cucumber Downy Mildew, Potato Late Blight and Pepper Phytophthora Blight in Korea

  • Kim, Dal-Soo;Prak, Hyun-Cheol;Chun, Sam-Jae;Yu, Seung-Hun;Park, Kyong-Ju;Oh, Jeung-Haing;Shin, Kwang-Hoon;Koh, Young-Jin;Kim, Byung-Sup;Hahm, Young-Il;Chung, Bong-Koo
    • The Plant Pathology Journal
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    • v.15 no.1
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    • pp.48-52
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    • 1999
  • Ethaboxam is the first proprietary fungicide developed in Korea, registered in 1998 and commercialized in 1999 by LG Chemical Ltd., Korea. It is a derivative of aminothiazole carboxamide and formulated into 25% wettable powder for practical application in fields. Ethaboxam effectively controlled cucumber downy mildew caused by Pseudoperonospora cubensis, potato late blight caused by Phytophthora infestans, and pepper Phytophthora blight caused by P. capsici, and was superior or comparable to the commercial standards, when foliarly sprayed 3∼5 times until dripping off at approximately 7-day intervals during the growing season. Ethaboxam was required at least 125 mg/liter and 250 mg/liter for effective control of cucumber downy mildew, and potato late blight and pepper Phytophthora blight, respectively. There was not phytotoxicity observed o leaves, stems or fruits of cucumber, potato and pepper from any trial.

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Selection of Bacillus amyloliquefaciens CC110 for Biological Control of Cucumber Downy Mildew Caused by Pseudoperonospora cubensis (오이 노균병의 생물적 방제를 위한 Bacillus amyloliquefaciens CC110균주 선발)

  • Lee, Sang Yeob;Weon, Hang Yeon;Kim, Jeong Jun;Han, Ji Hee
    • The Korean Journal of Mycology
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    • v.41 no.4
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    • pp.261-267
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    • 2013
  • In order to select antagonists for biological control of downy mildew of cucumber, 126 bacteria were isolated from cucumber plants collected from several locations in Korea. Among them, Five isolates were selected as potential biocontrol agents of cucumber downy mildew using a leaf disc bioassay method. In preventive and curative effect tests, the isolate CC110 was found to be effective to control downy mildew on cucumber showing diseased area by 0% whereas that of control was 15.0~18.0%. A bacterium isolate CC110 was identified as Bacillus amyloliquefaciens subsp. plantarum based on phylogenetic analysis using gyrB gene sequence. The culture liquid of isolate CC110 in TSB media were more effective for the control of the disease than those cultured in LB, NB, and KB media in leaf disk bioassay. when undiluted liquid, two-fold, five-fold diluted culture broth, and undiluted liquid, two-fold, five-fold diluted filtrate of isolate CC110 in TSB media were treated, diseased area of cucumber powdery mildew were 0%, 3.0%, 8.0%, 0%, 4.0% and 7.0%, respectively, whereas diseased area in the control was 21.0%. In the cucumber seedling tests, when the culture broth of isolate CC110 in TSB media was treated, diseased area were 35.0%, whereas that of control was 82.0%. When B. amyloliquefaciens CC110 was treated four times at five-day interval in the vinylhouse test, the control effect of cucumber downy mildew was higher than that treated three at seven-day interval.