• The Korean Journal of Pesticide Science
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• v.15 no.3
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• pp.323-328
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• 2011

Control efficacies of mixing of powdery mildew biofungicides with other control agents against major or fungal diseases of cucumber were investigated. Control efficacies against cucumber powdery mildew were quite different according to the kinds of biofungicides applied but those of powdery mildew biofungicides were increased by mixing application of two biofungicides. More than 80% of control efficacies on powdery and downy mildews of cucumber were obtained by mixing application of a powdery mildew biofungicide Bacillus subtilis KB-401 and a downy mildew chemical fungicide dimethomorph. Similarly, control efficacies on powdery and downy mildews of cucumber were 95% and 70% by mixing application of a powdery mildew biofungicide Bacillus subtilis KB-401 and cooking oils and yolk mixture, respectively.

• Research in Plant Disease
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• v.13 no.3
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• pp.197-203
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• 2007

An isolate of Ampelomyces quisqualis 94013(AQ94013) was selected as an effective parasite for biological control of cucumber powdery mildew. In the greenhouse, occurrence of cucumber powdery mildew was significantly suppressed for nine days by pre-treatment with $5.0{\times}10^6/ml$ and $5.0{\times}10^7/ml$ of conidial suspension of AQ94013. The disease was effectively controlled within three to seven days by post-treatment with the $5.0{\times}10^6/ml-conidial$ suspension of AQ94013. When AQ94013 was treated at concentration of $5{\times}10^6/ml$ three times at seven-day interval in the vinylhouse, the control effect was higher than that treated twice at ten-day interval and that treated with fenarimol twice. As the results, Ampelomyces quisqualis 94013 could be a prospective biofungicide for biological control of powdery mildew of cucumber.

• Research in Plant Disease
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• v.11 no.2
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• pp.167-172
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• 2005

An isolate of Ampelomyces quisqualis 94013 was selected as an effective parasite for biological control against cucumber powdery mildew. Temperature range for the parasitism of A. quisqualis 94013 against cucumber powdery mildew was $12\~30^{\circ}C$, and optimal temperature for that $20\~28^{\circ}C$. In $20\~35\%$ humidity of the greenhouse, parasitic ability of A. quisqualis 94013 against Sphaerotheca fusca was not good. Inoculation tests revealed that A. quisqualis 94013 can parasitize on six species of Sphaerotheca in the 12 crops and Ersiphe cichoracerum in tomato. As host rang of A. quisqualis 94013 was broad and it may be used effectively as a biocontrol agent for powdery mildew of 13 crops.

• Applied Biological Chemistry
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• v.51 no.2
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• pp.108-113
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• 2008

Azoxystrobin applied by aqueous WP suspension 50 mg/l was slightly absorbed into cucumber leaf in the absence of activator surfactant 24 h after spraying, but was increased to 25.7% by adding polyoxyethylene monohexadecyl ether (12 moles of ethylene oxide, CE-12) 500 mg/l. Only 4.1% of kresoxim-methyl WDG 100 mg/l in the absence of surfactant was absorbed into cucumber leaf 24 h after spraying, but was increased to 58.0% by adding polyoxyethylene monooctadecyl ether (14 moles of ethylene oxide, SE-14) 1,000 mg/l. The effect of CE-12 500 mg/l on foliar uptake of kresoxim-methyl at 50 mg/l was twice bigger than on azoxystrobin. Fungicidal activity of azoxystrobin WP against cucumber powdery mildew was marginally increased by adding surfactants to facilitate foliar uptake of azoxystrobin, so that the further increase of azoxystrobin uptake into cucumber plant by the addition of adjuvant was not a practical mean for enhancing the formulation efficacy in view of fungicidal activity. It was not possible for kresoxim-methyl to assess the adjuvant effect on the fungicidal activity in a greenhouse trial due to the vapor effect of active ingredient.

• Research in Plant Disease
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• v.26 no.3
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• pp.183-189
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• 2020

Powdery mildew is a common and serious disease of the Cucurbitaceae including cucumber (Cucumis sativus) in most areas of the world. To identify causal agents of the powdery mildew and their physiological race(s), we collected cucumber leaves displaying typical symptoms of powdery mildew from different locations in Korea. Based on morphological and molecular characteristics, all powdery mildew isolates were identified as an obligate biotrophic fungal pathogen, Podosphaera xanthii. After inoculation at melon (Cucumis melo) differentials to identify the fungal race(s), P. xanthii isolate MI180427 and IC190611 were identified as race 1 which has been repeatedly reported as dominant race in Korea. However, another isolate SE180328 produced different disease response in the tested differentials, being identified as race 2 which has not been reported in Korea. To confirm the race of SE180328, we inoculated additional melon differentials and determined the isolate as race 2F that is the prevalent race of powdery mildew in Beijing, China. Report of this new race 2F in Korea will be helpful for future breeding programs to develop resistant varieties to this race.

• Research in Plant Disease
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• v.12 no.3
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• pp.231-234
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• 2006

The influences of powdery mildew caused by Sphaerotheca fusca were assessed on cucumber to verify the economic injury level and yield response. Based on the relation of disease severity and yield response, economic threshold was determined by grading the disease severity of powdery mildew. Yield loss simulation due to damage of powdery mildew was conducted by defoliation of lower cucumber leaves in two seasons. The minimum number of leaves was 10 in spring season and 13 in autumn season which made no distinct difference on cucumber yield. The whole yields of cucumber was reduced as the disease severity was increased. Therefore occurrence of powdery mildew have a negative effect on cucumber yield. The regression equation between disease severity and yield loss showed Y=-57.237x+6143.1, $R^2=0.9628$. This equation suggests the disease severity of economic threshold is 17.6%, which is 3% reduction point of yield based on yield and economic relations. These results suggest that application of fungicide should be needed when 1 or 2 leaves of cucumber are infected by powdery mildew in the growing season.

• The Korean Journal of Mycology
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• v.29 no.2
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• pp.116-122
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• 2001

An isolate of the prospective hyperparasite, Ampelomyces quisqualis 94013 (AQ94013) was selected for the use of biological control of cucumber powdery mildew caused by Sphaerotheca fuliginea. Examination for the parasitism processes by scanning electron microscopy and light microscopy showed that conidia of AQ49013 germinated on conidia, conidiophores and hyphae of Sphaerotheca fuliginea four hours after inoculation. Appressorium-like structures were developed and attached to the hyphae of S. fuliginea seventeen hours after inoculation. Hyphae of AQ94013 penetrated into hyphae of S. fuliginea twenty-four hours after inoculation. Pycnidia of AQ94013 were produced in the hyphae and the basal part of conidiophores of S. fuliginea fourty four hours after inoculation. The pycnidia of AQ94013 matured foully eight hours after inoculation, and the conidia were discharged from the ostioles of the pycnidia fifty two hours after the inoculation. At the same time, hyphae and conidiophores of S. fuliginea were distorted and died. Also, concentrated culture filtrate and culture filtrate of AQ94013 had not suppressed the cucumber powdery mildew fungus as water treatment. Therefore, mode of action of AQ94013 was assumed to be parasitism on powdery mildew fungi.

• The Korean Journal of Mycology
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• v.41 no.4
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• pp.268-273
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• 2013

Bacillus amyloliquefaciens M27 was isolated from the cotton-waste compost for cultivation of oyster mushroom (Pleurotus ostreatus). B. amyloliquefaciens M27 is a biocontrol agent with antagonistic activities against a wide range of fungal pathogens. The aim of this work was to evaluate the possibility of exploiting antagonistic bacteria, B. amyloliquefaciens M27, in the biological control of the cucumber powdery mildew fungus, Podosphaera fusca. In greenhouse tests, the isolate was found to be very effective to control powdery mildew on cucumber leaves showing 4.0% diseased area, whereas diseased area in the control was 80.5%. The filtrate of the isolate cultured on MH and LB media were more effective for control of the disease than those cultured on TSB, NB, and KB media. When two, five, ten, 20, 50 and 100-fold diluted culture broth of isolate on LB media were treated, disease areas were 0%, 0%, 0%, 1.3%, 3.1% and 5.0%, respectively, whereas diseased area in the control was 60.0%. The filtrate of the isolate cultured on LB media was treated to cucumber plants on July, October and December just before the outbreak of the powdery mildew occurred. When 10-fold diluted filtrate of the isolate was treated, control efficacy was 88.9~98.9% in the treated seasons. The results showed that the culture filtrate of B. amyloliquefaciens M27 was very effective to control powdery mildew of cucumber.

• Korean Journal of Organic Agriculture
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• v.17 no.4
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• pp.557-566
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• 2009

This study was conducted to develop an organic control of powdery mildews of cucumber by using mayonnaise in green house. The treatment of 0.1~2% mayonnaise resulted in 8.3%~99.2% control efficiencies against powdery mildew of cucumber. 0.5% mayonnaise treatment resulted control values over 97% in disease. It did not adversely affected the photosynthesis of foliages. Although one application of mayonnaise to the foliage was not practically effective enough, two or three application of mayonnaise to the foliage at the 0.5% concentration resulted in excellent control against powdery mildews. This treatment could provide protection for 10~14 days after application. Among the type of mayonnaise, general mayonnaise revealed 97.5% control value, but mayonnaise containing low oil content revealed 39.3%~97.5% control values on powdery mildews at the 0.5% concentration. Therefore, oil content in mayonnaise played a essential material to control powdery mildew. Results indicated that mayonnaise could be used as organic control of powdery mildews of cucumber. This control might be environmentfriendly as well as cost-effective.

• The Korean Journal of Pesticide Science
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• v.10 no.4
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• pp.359-366
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• 2006

The protective effect of kresoxim-methyl was investigated on 6 important plant diseases, and the vapour effect of it did on barley and cucumber powdery mildews, respectively. With 2.0 ${\mu}g\;mL^{-1}$ of kresoxim-methyl, its high activities against wheat leaf rust and barley powdery mildew were showed such as 92 and 100%, while activities were very low against rice sheath blight, tomato gray mold, and tomato late blight. In vapour phase control activity of kresoxim-methyl against barley powdery mildew was positively correlated with the applied concentrations, except for azoxystrobin and metominostrobin. With 200 ${\mu}g\;L^{-1}$, its control value was 71.9%. When 1000 ${\mu}g\;m^{-3}$ of kresoxim-methyl in vapour phase was applied on 4 plants of cucumber in a vinyl chamber, 51.1% of control value on kresoxim-methyl-treated cucumber was showed 7 days after the application.