• Korean Journal Plant Pathology
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• v.14 no.6
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• pp.618-621
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• 1998

In pseudoperonospora humuli, the cause of hop downy mildew, environmental and host factors affecting laboratory production of oospore were examined. After 7 days incubation of leaf disk inoculated with sporangia on water, additional incubations were carried out under different conditions of temperature and moisture. Oospore production was also compared between very susceptible (Nugget) and resistant (Fuggle) hop cultivars. Oospores were not produced at 18$^{\circ}C$ regardless of other incubation conditions. Leaf disks failed to produce oospore when incubated on water for up to 18 days at 8$^{\circ}C$. No oospores formed on infection sites without necrosis. However, abundant oospores were produced at necrotized infection sites when inoculated leaf disk incubated on dry filter paper for 5 days at 8$^{\circ}C$. Both susceptible and resistant hop cultivars produced abundant oospores. In the measurement of optimal temperature for oospore production, oospores were produced at 6 to 12$^{\circ}C$ Most abundant oospores were produced at 8$^{\circ}C$. We suggest that proper combination of low temperature, dryness and necrosis may be a critical environmental factors for oospore production of P. humuli.

• 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.

• 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.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 1997.06a
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• pp.42-46
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• 1997

• Korean Journal of Organic Agriculture
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• v.17 no.2
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• pp.253-264
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• 2009

This study was conducted to establish agricultural practices to control diseases and insects for chemical pesticide-free cultivation of leafy vegetables. Two diseases, gray mold(Botrytis cinerea) and soft rot(Erwinia carotovora), on lettuce were reduced by controlling temperature and humidity using air-circulation fan. The aphidophagous lady beetle(Harmonia axyridis) and primary parasitoids(Aphidius colemani) showed activity to control aphids density on Chinese cabbage. Co-application of cooking oil and yolk mixture (COY) and BT(Bacillus thuringiensis) decreased diseases including soft rot(Erwinia carotovora), downy mildew(Peronospora brassicae Gaumann), and powdery mildew(Eryslphe polygoni), and insects such as diamondback moth(Plutella xylostella) and beet armyworm(Spodoptera exigua Hubner). Neem extract treatment reduced downy mildew(Peronospora destructor) on Welsh onion.

• The Korean Journal of Pesticide Science
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• v.14 no.4
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• pp.326-331
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• 2010

Bacillus subtilis B29, B. subtilis M10 and Streptomyces sp. CC19 obtained from phyllosphere of cucumber plants were selected for biological control of fungal air-borne diseases. For the downy mildew, diseased area of B. subtilis B29, B. subtilis M10 and Streptomyces sp. CC19 showed 0.5%, 20.2% and 42.0%, but that of control was 82.0% respectively, in cucumber seedling test. Incidence of powdery mildew by once application of B. subtilis B29, B. subtilis M10 and Streptomyces sp. CC19 was 2.8%, 3.6% and 12.3%, respectively, whereas that of control was 65.6%. On the gray mold, diseased area of B. subtilis B29, B. subtilis M10 and Streptomyces sp. CC19 was 8.0%, 30.8% and 5.2%, respectively, compared to 81.2% for the control. Therefore, B. subtilis B29 could be a prospective antagonist for biological control of powdery mildew, downy mildew and gray mold of cucumber plant.

• The Plant Pathology Journal
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• v.25 no.3
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• pp.280-285
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• 2009

Powdery and downy mildews caused by Sphaerotheca fusca and Pseudoperonospora cubensis are the most common and serious diseases of cucumber worldwide. In spite of the introduction of highly effective systemic fungicides, control of these diseases remains elusive. Hence, this study aimed to develop an alternative method to chemicals in controlling the diseases by using different types of cooking oil. Egg yolk, which contains a natural emulsifier, lecithin, was selected as a surfactant to emulsify the oils. Among the different cooking oils used, soybean, canola (rape seed), safflower, sunflower, olive, and corn oils showed over 95% control values against powdery mildew of cucumber in a greenhouse test. In particular, 0.3% canola oil emulsified with 0.08% yolk (1 yolk and 60 ml canola in 20 l spray) was found to be the most effective. The treatment resulted in 98.9% and 96.3% control efficacies on powdery and downy mildews, respectively, of cucumber in the field. Canola oil exhibited direct and systemic effect, wherein powdery mildew of cucumber was suppressed only on treated leaves but not on non-treated leaves in a plant, while mycelia and conidia of the pathogen were severely distorted or destroyed by the treatment. The prospect of using the canola oil and yolk mixture as a natural fungicide is highly promising because of its effectiveness, availability, low cost, simple preparation, and safety to humans and the environment. The use of the canola oil and yolk mixture is expected to be an effective fungicide for use in organic farming and home gardening.

• Korean Journal of Agricultural Science
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• v.42 no.4
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• pp.325-333
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• 2015

The ventilation systems composed three types of side vent (roll-up) 'SV', side vent+roof vent 'SV+RV', and side vent+roof fan 'SV+RF' with 7.5 m spacing, with specific set point temperatures for ventilation: SV ($35^{\circ}C$ open / $33^{\circ}C$ close), SV+RV or SV+RH ($35^{\circ}C$ open/$33^{\circ}C$ close for root ventilation and $37^{\circ}C$ open / $35^{\circ}C$ close for side vent). In the treatment of SV+RV, although the average daily maximum temperature inside the greenhouse temporarily increased by $38-40^{\circ}C$, thermal stress by high temperature did not occur and the disease incidence (%) of powdery mildew and downy mildew on the oriental melon were 25 - 75% lower than in the conventional SV treatment. In the SV treatment, the disease incidence (%) of powdery mildew and downy mildew were 1.4 - 7.7% and 4.2 - 15.9% for 'Deabakkul', and 20.3 - 22.8% and 2.8 - 11.3%, for 'Ildeungkkul'. The yield for one month was higher in the treatment of SV+RV than those in other treatments, with values of 2,105 kg/10a for 'Deabakkul' and 2,537 kg/10a for 'Ildeungkkul'. The simultaneous treatment with side vent and roof vent resulted in 16.2% higher yield (18.1% higher marketable yield) than that in the SV treatment for 'Deabakkul'.

• The Plant Pathology Journal
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• v.25 no.3
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• pp.302-302
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• 2009

See Full Text

• The Plant Pathology Journal
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• v.25 no.4
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• pp.433-433
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• 2009