• Research in Plant Disease
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• v.12 no.1
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• pp.51-54
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• 2006

The effectiveness of four plant oils (garlic, ginger, cinnamon and lemongrass) against a range of plant pathogenic organisms was tested in vitro. Of the four oils, two oils (garlic and cinnamon) showed relatively good antimicrobial activities. Activity of garlic oil was shown against the plant pathogenic bacteria Agrobacterium tumefaciens, Ewinia carotovora, Ralstonia solanacearum, Xanthomonas campestris, and the fungi Phytophthora infestans, Fusarium oxysporum, Collectotricum sp., whereas Acidovorax avenae and Pythium sp. showed the resistance towards garlic oil. Results from the planta bioassays under greenhouse conditions indicated that garlic oil significantly reduced the cucumber powdery mildew (Sphaerotheca fusca) and tomato powdery mildew (Erysiphe cichoracearum) showing control value 70.0-74.6% and 71.2%, respectively.

• The Korean Journal of Mycology
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• v.20 no.4
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• pp.309-314
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• 1992

Nine species of powdery mildew fungi were examined to understand the change in size of conidia in relation to air temperature. Of these, Sphaerotheca aphanis, S. fusca and S. pannosa showed constant value of conidial sizes regardless of changes in air temperature. The length/width ratio in the conidia of Erysiphe, artemisiae and E. sordida increased as the air temperature rose. E. cichoracearum gave the result against that shown in the above two species of Erysiphe. The conidia of Microsphaera pseudolonicerae became decreased in their width as the air temperature fell. The length/width ratio of conidia was markedly increased. M. alphitoides and M. robiniae showed variable size measurements in conidia regardless of changes in air temperature and studies for it needed for additional examination in future.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.30-31
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• 2003

Total 291 isolates of Ampelomyces quisqualis were obtained from 32 species of powdery mildew fungi and a selected isolate, Ampelomyces quisqualis 94013 (AQ94013) effectively hyperparasitized 6 species of Sphaerotheca and one species of Erysiphe which cause serious damage on many important crops in Korea. Moreover, AQ94013 showed antagonistic effects against 12 major fungal plant pathogens as well. Results indicated that the present isolate is not a host specific hyperparasite and has a broad spectrum of biocontrol potential. Providentially, AQ94013 revealed resistance to a number of agrochemicals so as to be applied with the chemicals reciprocally.(중략)

• Journal of Microbiology and Biotechnology
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• v.4 no.4
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• pp.349-353
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• 1994

An isolate 90-GT-302, identified as Kitasatosporia kimorexae, was found to produce antibiotics that induce mycelial swelling in Magnaporthe grisea, and Fusarium solani. The strain produced at least 5 antibiotics. Among them, the main active compound designated as kimorexin A was isolated and its physico-chemical properties and biological activities were examined, and as a result was found to be of the thiopeptide antibiotic. A comparison between the properties of kimorexin A and those of the known thiopeptide antibiotics led us to conclude that kimorexin A was a new thiopeptide polythiazolyl antibiotic. Kimorexin A showed a narrow antimicrobial spectrum against very limited genus of phytopathogenic fungi. It prevented host plants from infections of Rhizoctonia solani and absolute parasitic fungi, such as Sphaerotheca fuliginea and Puccinia recondita, almost completely at the treatment concentration of approximately 20 ppm.

• Korean Journal Plant Pathology
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• v.12 no.1
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• pp.85-90
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• 1996

대황 추출물(RK)과 화학약품 1, 8-dihydroxy anthraquinone(AK)을 제제화하여 오이 흰가루병에 대한 약효, 약해 및 어독성을 조사하였다. 제제화한 RK와 AK 약제를 하우스에서 500배, 1000배 희석농도로 처리했을 경우 오이 흰가루병에 대하여 100%의 방제효과를 나타냈고, pot에서 2,000배, 3,000배, 5,000배 희석농도로 처리했을 때 모두 75% 이상의 방제효과를 나타냈다. 또 노지에서 4,000배, 5,000배 희석농도로 처리해도 75.3% 이상의 방제효과를 나타냈다. RK 약제는 250배 희석농도에서 오이에 약해가 없었으나 AK 약제는 250배 희석농도에서 약해가 있었다. 어독성은 두 약제 모두 반수치사농도(TLm)가 2ppm 이상으로 독성은 낮은 것으로 판정되었다.

• Korean Journal of Microbiology
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• v.7 no.1
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• pp.22-28
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• 1969

Twenty-nine specimens of the infected plans were collected from areas through the country since 1967 to 1968. We report here four unrecorded causla organisms of powdery and their hosts which were identified in this work. The results as as follows : 1. Microsphaera diffusa Cooke et Peck (M.magnoliae Sawoda) (Host:Magnolia obovata Thunb.) 2. Sphaerotheca humili (de Condolle0Burill. (Host: Spirea sp.) 3. Phyllactinea fraxini (de Condolle)Homma. (Host : Betuls sp.) 4. Uncinula sengorui.Salmon.(Host : Celastrus orbiculatus, Thunb.) * Six unrecorded host 1. Altemisia japonica. Thunb. (Pathogen : Erysiohe cichoracearum DC.) 2. Aster tataricus. L. (Pathogen :Sohaerotheca fuliginea (Schlechtendahl) Poll. 3. Dohlia variabilis Defont. (Pathogen :Sphaerotheeca fuliginea (schlechtendahl) poll. 5. Helianthus ammues (Pathogen :Spherotheca fuliginea schlechtendahl) poll. 6. Solanum melangera L. (Pathogen : Erysiphe cichoracearum DC.)

• Research in Plant Disease
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• v.20 no.1
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• pp.31-36
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• 2014

Alternative spraying was developed using fungicides and potassium phosphonate to control watermelon powdery mildew (WPM) caused by Sphaerotheca fusca under greenhouse condition. In 2010 trial, a total of 9 combinations of 6 fungicides which are legally registered in Korea and currently used on watermelon farms were tested for the control efficacy against WPM. Though the combination of chlorothalonil (Chl)-myclobutanil (My)-fenarimol (Fen)-hexaconazole (Hex) was the most effective (82.6%) in the first-year trial, it had the problem that My, Fen and Hex have the same mode of action. Therefore, in the second-year trial to improve the fungicide combination and to reduce fungicide application, fungicides and potassium phosphonate (P) combinations were tested for WPM control using 500 ppm aqueous potassium phosphonate solution which is both eco-friendly and showing different mode of action from the fungicides tested. The P-My-Fen-Hex applied at 10-day intervals provided relatively high control (75.6%), whereas Chl-My-Fen-P provided 31.8% control. To improve the control, fungicides and P were applied at 7-day intervals in the third-year trial. Though Chl-My-Fen-Hex provided the highest control (89.6%), P-My-Fen-Hex also provided relatively high control (83.5%) compared to 65.9 % control with Chl-My-Fen-P, which suggests that Chl-My-Fen-Hex could be replaced with P-My-Fen-Hex for WPM control.

• Research in Plant Disease
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• v.10 no.3
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• pp.159-166
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• 2004

This study were carried out to identify pathogens and determine the seasonal occurrence and chemical control of safflower (Carthamus tinctorius) diseases from 2000 to 2002 in Gyengbuk province, Korea. Major diseases of safflower were, anthracnose caused by Colletotricum acutatum in open field, and gray mold by Botrytis cinerea in rain sheltered plastic house. Other diseases occurred were powdery mildew caused by Sphaerotheca fuliginea, collar rot by Sclerotium rolfsii, leaf spot by Alternaria carthami and A. alternata, rust by Puccinia carthami, root-rot and stem-rot by Phytophthora cactorum, root-rot and wilt by Fusarium oxysporum and damping-off by Pythium ultimum. Seasonal occurrence of anthracnose on safflower has begun from late April, and increased until harvesting, especially rapid increased after rainfall during stem elongation season that is from May to June. In open fields, maximum incidence of anthracnose was 67 ％ in late July. But in rain-sheltered plastic house, it was very low, about 5％ in July. Gray mold caused by Botrytis cinerea was most important disease in rain-sheltered plastic house cultivation. Maximum incidence of gray mold on floral head was 27.4％, whereas other diseases occurred below 1 ％. In the test of the chemical control of the safflower anthracnose, metiram WP, carbendazim$.$kasugamycin WP and iminoctadintris$.$thiram WP were the highest controlling chemicals. In chemical control of gray mold, iminoctadintris$.$thiram WP, fluazinam WP and iprodion WP showed highest controlling effects.

• The Korean Journal of Pesticide Science
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• v.4 no.2
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• pp.37-43
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• 2000

Effects of silicon application on development of colonies of Sphaerotheca fuliginea were examined. Cucumber plants were applied with nutrient solutions amended with different concentrations of soluble silicon and selected leaves were inoculated with known concentrations of conidia of the pathogen. Colony number per leaf, colony area per leaf, and germination rate of conidia of S. fuliginea collected from the inoculated leaves were reduced as silicate concentrations in the nutrient solutions increased from 0.05 to 4.10 mM. The increase in resistance of plants to mildew infection was apparently due to silicate accumulation in leaves, and there was no correlation between cation or ionic strength effects and the silicate treatments. Silicate treatment in growth medium remarkably suppressed powdery mildew development on cucumber. Colonies of mildew fungus were visible with over approx. 38.3% of the mature leaf surface, while that of the leaves in high Si plants was 2.3% observed at 51 days after transplanting. No significant differences were observed between 1.7 mM and 3.4mM silicate treatments. Conidial germination rates were significantly reduced by increasing Si amendments. Conidial germination ranged from 14.7 to 20.3% for plants grown in low Si solution(<1.40 mM), and from 9.0 to 12.4% for plants grown in high Si solution(>1.8 mM). Foliar applications of Si with ${\geq}$ 17.0 mM decreased the number of powdery mildew colonies. Persistence of Si foliar sprays effects on cucumber demonstrated that the 17 mM Si spray applied 4 days before inoculation with S. fuliginea reduced mildew colony formation. The relationship was positive and linear.

• Research in Plant Disease
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• v.13 no.3
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• pp.191-196
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• 2007

An isolate of Ampelomyces quisqualis 94013(AQ94013) was selected as an effective agent for biological control against cucumber powdery mildew. In order to develop mass production technique, six cereal media made with barley, rice, mille and brown rice, sorghumand rice seed were tested. Among them, barley medium was the best for the growth and conidial production of AQ94013. Optimum temperature for the mass production of AQ94013 was $25^{\circ}C$ and followed by $20^{\circ}C$ and $30^{\circ}C$. Light radiation inhibited conidial production of AQ94013 since number of conidia formed on barely medium under continuous light or 12 hrs alternative light were much less than cultured in darkness. Tthe conidia produced on the medium at $30^{\circ}C$ maintained the parasitic ability to Sphaerotheca fusca for 30 days. A culture method of AQ94013 in barley liquid medium with adding barely power(40 g/l) in darkness for five days at $25^{\circ}C$using a 30 l-fermenter was very effective for mass production of conidia.