• Mycobiology
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• v.41 no.3
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• pp.164-166
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• 2013

A Bacillus sp. BS061 significantly reduced disease incidence of gray mold and powdery mildew. To identify the active principle, the culture filtrate was partitioned between butanol and water. The antifungal activity against B. cinerea was evident in the butanol-soluble portion, and active substances were identified as cyclic lipopeptides, iturin A series, by nuclear magnetic resonance spectrometry (NMR) and mass analysis. Interestingly, antifungal activity against powdery mildew was observed in the water-soluble portion, suggesting that cyclic lipopeptides have no responsibility to suppress powdery mildew. This finding reveals that biocontrol agents of Bacillus origin suppress gray mold and powdery mildew through the secretion of different bioactive substances.

• Mycobiology
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• v.45 no.4
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• pp.409-420
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• 2017

Foliar sprays of three plant resistance inducers, including chitosan (CH), potassium sorbate (PS) ($C_6H_7kO_2$), and potassium bicarbonates (PB) ($KHCO_3$), were used for resistance inducing against Erysiphe cichoracearum DC (powdery mildew) infecting okra plants. Experiments under green house and field conditions showed that, the powdery mildew disease severity was significantly reduced with all tested treatments of CH, PS, and PB in comparison with untreated control. CH at 0.5% and 0.75% (w/v) plus PS at 1.0% and 2.0% and/or PB at 2.0% or 3.0% recorded as the most effective treatments. Moreover, the highest values of vegetative studies and yield were observed with such treatments. CH and potassium salts treatments reflected many compounds of defense singles which leading to the activation power defense system in okra plant. The highest records of reduction in powdery mildew were accompanied with increasing in total phenolic, protein content and increased the activity of polyphenol oxidase, peroxidase, chitinase, and ${\beta}$-1,3-glucanase in okra plants. Meanwhile, single treatments of CH, PS, and PB at high concentration (0.75%, 2.0%, and/or 3.0%) caused considerable effects. Therefore, application of CH and potassium salts as natural and chemical inducers by foliar methods can be used to control of powdery mildew disease at early stages of growth and led to a maximum fruit yield in okra plants.

• Research in Plant Disease
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• v.14 no.3
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• pp.201-204
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• 2008

We've been involved in collection and domestication of Agrimonia pilosa from 2005 to 2007. We observed agrimony powdery mildew caused by Sphaerotheca aphanis. The powdery mildew developed twice a year, in May to June and mid August to September on whole plants of A. pilosa plants, that is, leaves, stem and floral part. We sprayed the Cooking Oil & Yolk mixture (COY) to control the agrimony powdery mildew. When COY was single-sprayed to control agrimony powdery mildew, its control value was 26.9%. However when it was double-sprayed and triple-sprayed at seven days interval, its control value increased up to 80.8 and 82.7%, respectively. Upon the first spray, symptoms of powdery mildew disappeared within three days and suppressive effect of COY was persisted for only seven days. Thereafter, powdery mildew was relapsed to develop. However, on double to triple sprays, powdery mildew was suppressed more than 28 days after final treatment. Therefore, it is concluded that double spray of COY at seven days interval can control effectively agrimony powdery mildew.

• Mycobiology
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• v.37 no.4
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• pp.308-309
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• 2009

Powdery mildews on over 40 plants in Bangalore were screened during July-December of 2003~2008. Isolates from mycoparasitised Oidium caesalpiniacearum of Bauhinia purpurea comprised Lasiodiplodia theobromae, in addition to Ampelomyces quisqualis. Koch's postulates were satisfied to establish the mycoparasitism of L. theobromae. This is the first report that L. theobromae acts as a mycoparasite of a powdery mildew.

• Research in Plant Disease
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• v.16 no.3
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• pp.285-289
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• 2010

The experiments were carried out in fields for two years from 2008 to assess yield losses of squash due to powdery mildew caused by Sphaerotheca fuliginea and to determine its economic thresholds. Powdery mildew disease was first observed in late June, about 50 days after field-transplanting, progressed rapidly during late July to early August, and began to reduce from late August. Powdery mildew severity was negatively correlated with squash yields. A positive correlation was observed between fruit weight and % marketable fruits. A simple linear regression model was obtained as Y=-10.399 X + 6607.5 with $R^2$ = 0.9700 when squash yields (Y) was predicted using powdery mildew severity as an independent variable(X). Spray threshold for maximizing squash yields without economic considerations was estimated as 6.5% in terms of leaf lesion area with powdery mildew. Economic threshold and economic spray threshold able to compensate the costs of fungicide sprays were determined as 21.6% and 17.3% in leaf lesion area, respectively.

• Journal of Korean Society of Forest Science
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• v.58 no.1
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• pp.54-59
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• 1982

Powdery mildew has been observed on the several clones of Populus euramericana, P. deltoides, P. deltoides ${\times}$ P. maximowiczii in the nurseries of Chuncheongan-do and Kangwoen-do forest Research Institute in mid-October 1982. Powdery mildew fungus of Populus spp. was identified as phyllactinia guttata(Waller. ex Fr.) $L{\acute{e}}v$ which was reported as the powdery mildew fungus of Populus tomentosa Carr. Powdery mildew of Populus spp. caused by this fungus has not previously been reported in Korea. When we surveyed the occurrence of powdery mildew disease the leaves of P. deltoides R-89 were severely attacked by this fungus.

• The Plant Pathology Journal
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• v.36 no.2
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• pp.111-120
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• 2020

Powdery mildew of Indian mustard (Brassica juncea), caused by Erysiphe cruciferarum, is emerging as major problem in India. All the Indian mustard cultivars presently grown in India are highly susceptible to powdery mildew and so far no resistance source has been reported. In this study, with an aim to identify resistant source, 1,020 Indian mustard accessions were evaluated against E. cruciferarum PMN isolate, at Wellington, The Nilgiris, Tamil Nadu, India under natural hot spot conditions. The study identified one accession (RDV 29) with complete resistance against E. cruciferarum PMN isolate for the first time, which was consistent in five independent evaluations. Genetic analysis of F₁, F₂ and backcross populations obtained from the cross RSEJ 775 (highly susceptible) × RDV 29 (highly resistant) for two season revealed that the resistance is governed by two genes with semi-dominant and gene dosage effect. Further, a new disease rating system using six scales (0, 1, 2, 3, 4, and 5) has also been proposed in this study to score powdery mildew based on progress of fungal growth in different plant parts of the F₂ population. The outcome of this study viz. newly identified powdery mildew-resistant Indian mustard accession (RDV 29), information on inheritance of resistance and the newly developed disease rating scale will provide the base for development of powdery mildew-resistant cultivars of Indian mustard.

• Research in Plant Disease
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• v.22 no.3
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• pp.133-144
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• 2016

Powdery mildew (Podosphaera xanthii) causes severe damage to pumpkin crops grown in open fields and plastic house. Initially, we used ten accessions of pumpkin species; Cucurbita pepo (3), C. maxima (2), C. moschata (2), and C. argyrosperma (3) to study the disease progress in different stages of seedling development. Commercial pumpkin varieties were used as susceptible host for inoculum management and young seedlings were inoculated by dusting powdery mildew spores on the cotyledons, 1-true-leaf and 2-true-leaf seedling stages. Based on initial study, we further evaluated 218 pumpkinaccessions for their resistance to powdery mildew in different seedling stages under plastic house. Area under disease progress curve (AUDPC) and relative AUDPC (rAUDPC) was higher in cotyledonary and 1-true-leaf than 2-true-leaf stage. Seedlings at cotyledons and 1-true-leaf seedling stage displayed more susceptibility to powdery mildew. Based on evaluation of 2-true-leaf stage, IT 110859 and IT 278459 from C. pepo and C. argyrosperma identified as resistant (<0.2). Of the 228 pumpkin accessions, 21 (9.2%) pumpkin accessions consisting of C. pepo (2), C. maxima (5), C. moschata (13), and C. argyrosperma (1) exhibited intermediate resistance (<0.4) to powdery mildew and these accessions are useful to growers for its rational management.

• Research in Plant Disease
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• v.18 no.2
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• pp.80-85
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• 2012

We examined the incidence of powdery mildew in strawberry cv. Seolhyang plants, and performed a comparative analysis on the temperature, photosynthesis rate, and nutrient content of healthy and powdery mildew-infected plants. Powdery mildew first infected the fruit of the strawberries in mid-January, and the disease severity increased in both fruits and leaves during the late harvest season. The rate of photosynthesis and leaf temperatures of healthy plants were higher than those of powdery mildew-infected leaves and significantly decreased with an increase in the disease severity. The healthy and powdery mildew-infected plants in the soil analysis were not significantly different in chemical compositions. The leaves of the healthy plants contained lower potassium and higher manganese and chlorophyll concentrations than the powdery mildew-infected plants. In particular, manganese was significantly higher in healthy leaves than in infected leaves. Therefore, the concentrations of potassium, manganese and chlorophyll in strawberry leaves may be an important factor for disease suppression.

• Research in Plant Disease
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• v.7 no.1
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• pp.31-36
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• 2001

To establish an effective chemical control strategy against powder mildew of sweet pumpkin (Cucurbita maxima Duchesne) caused by Sphaertheca fuliginea, screening of effective fungicides and determination of their application times were conducted. Powdery mildew caused by S. fuliginea began to occur at about 80 days after transplanting and continuously increased until harvesting in Korea. Systemic fungicides, such as difenoconazole, triforine, bitertanol, and triflumizole, were effective for controlling powdery mildew, showing control efficacies of about 80-90%. When the fungicide triflumizole was applied 3 or 4 times from the beginning day of the disease at 10-day intervals, about 92.0% and 94.6% of disease control and yield increase of 7% and 9% were obtained, respectively. Therefore, the proper application of triflumizole for controlling powdery mildew of sweet pumpkin must be done more than 3 times.