• Journal of Microbiology and Biotechnology
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• v.16 no.3
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• pp.465-468
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• 2006

Even though many pesticides are known for barley powdery mildew and wheat leaf rust, alternative controls are necessary, because of consumer rejection of chemical pesticides and the appearance of fungi resistant to fungicides. To discover biopesticides, many broths of microorganisms were screened. Of those, a culture broth of Burkholderia ambifaria showed an excellent antifungal activity against both Erysiphe graminis and Puccinia recondita, which cause barley powdery mildew and wheat leaf rust, respectively.

• Korean Journal Plant Pathology
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• v.11 no.4
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• pp.380-382
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• 1995

Yellow spot or blotch symptoms on the upper surface of leaf, without the production of velvet-like fungi on the lower surface of leaf as in the gray mold of tomato caused by Cladosporium fulvum, were observed in tomato (cv. Seokwang) plants in May, 1995, in a vinyl-house of the experimental plot of Gyeongnam Provincial Rural Development Administration, Chinju, Gyeongnam, Korea. We identified this disease as powdery mildew of tomato caused by Oidiopsis taurica (L v.) Arnaud (=Leveillula taurica), which was new to Korea. Conidia of the fungus were borne on uni- or bi-septated conidiophores which were developed through the stomata of the tomato leaf. The conidia were slender, clavate and variable in size (31~111.6$\times$13.1 ${\mu}{\textrm}{m}$). The fungal conidia isolated from tomato leaves were inoculated to tomato plants, and the occurrence of the same disease was confirmed based on the symptomatology and the morphology of the pathogen reisolated.

• Research in Plant Disease
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• v.15 no.1
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• pp.23-29
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• 2009

Cooking oil and yolk mixture (COY), a environmentally acceptable plant protection agent, and COY+$CaCO_3$+neem oil mixture were studied to control the powdery mildew occurring on eggplant, paprika, cherry tomato and maturity tomato in glass houses and vinyl houses during 2005 to 2007. The morphological changes of the pathogenic fungi on the leaf surface before and after treatment of COY were observed. COY made of rape seed oil and COY+$CaCO_3$+neem oil mixture were sprayed three times with 5 days interval to foliar parts of eggplant, paprika and tomato and the disease development were examined 5 days after final spray. In eggplant, the control efficacy of COY to powdery mildew was 94.6%. In paprika, the control efficacy of COY to powdery mildew was 91.6% and that of COY+$CaCO_3$+neem oil mixture was 96.2% that revealed little higher than COY itself. In tomatoes(cherry or maturity tomato), the control efficacy of COY were about 91 %, however, when COY mixture were sprayed to tomato leaves and stems the powdery mildew was controlled completely. Typical and healthy mycelia, conidiophores and condia were observed through scanning electron microscope in COY unsprayed leaf surface, on the other hand destroyed and winkled mycelia and conidiophores were observed in COY treated leaves regardless host plants nor taxonomic differences of fungi.

• 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.

• Mycobiology
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• v.33 no.2
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• pp.97-103
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• 2005

Crude extracts and active principles from medicinal plants have shown potential role in controlling plant diseases in glasshouses as well as in fields as one of the safest and ecofriendly methods. The effect of nor-securinine (an alkaloid) isolated from Phyllanthus amarus has been seen against spore germination of some fungi (Alternaria brassicae, A. solani, Curvularia pennisetti, Curvularia sp., Erysiphe pisi, Helminthosporium frumentacei) as well as pea powdery mildew (Erysiphe pisi) under glasshouse conditions. The sensitivity of fungi to nor-securinine varied considerably. Nor-securinine was effective against most of the fungi. H. frumentacei was more sensitive even at the lowest concentration ($1,000\;{\mu}g/ml$). Likewise conidia of E. pisi were also inhibited in partially or completely appressorium formation. Pre-inoculation treatment showed greater efficacy than post-inoculation in inhibiting powdery mildew development on pea plants in a glasshouse. Maximum inhibition occurred at $2000\;{\mu}g/ml$.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 1995.06b
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• pp.27-53
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• 1995

In plant pathology there is an increasing necessity for improved cytological techniques as basis for the localization of cellular substances within the dynamic fine structure of the host-(plant)-pathogen-interaction. Low temperature (LT) preparation techniques (shock freezing, freeze substitution, LT embedding) are now successfully applied in plant pathology. They are regarded as important tools to stabilize the dynamic plant-pathogen-interaction as it exists under physiological conditions. - The main advantage of LT techniques versus conventional chemical fixation is seen in the maintenance of the hydration shell of molecules and macromolecular structures. This results in an improved fine structural preservation and in a superior retention of the antigenicity of proteins. - A well defined ultrastructure of small, fungal organisms and large biological samples such as plant material and as well as the plant-pathogen (fungus) infection sites are presented. The mesophyll tissue of Arabidopsis thaliana is characterized by homogeneously structured cytoplasm closely attached to the cell wall. From analyses of the compatible interaction between Erysiphe graminis f. sp. hordei on barley (Hordeum vulgare), various steps in the infection sequence can be identified. Infection sites of powdery mildew on primary leaves of barley are analysed with regard to the fine structural preservation of the haustoria. The presentation s focussed on the ultrastructure of the extrahaustorial matrix and the extrahaustorial membrane. - The integration of improved cellular preservation with a molecular analysis of the infected host cell is achieved by the application of secondary probing techniques, i.e. immunocytochemistry. Recent data on the characterization of freeze substituted powdery mildew and urst infected plant tissue by immunogold methodology are described with special emphasis on the localization of THRGP-like (threonine-hydrxyproline-rich glycoprotein) epitopes. Infection sites of powdery mildew on barley, stem rust as well as leaf rust (Puccinia recondita) on primary leaves of wheat were probed with a polyclonal antiserum to maize THRGP. Cross-reactivity with the anti-THRGP antiserum was observed over the extrahaustorial matrix of the both compatible and incompatible plant-pathogen interactions. The highly localized accumulation of THRGP-like epitopes at the extrahaustorial host-pathogen interface suggests the involvement of structural, interfacial proteins during the infection of monocotyledonous plants by obligate, biotrophic fungi.

• 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.48 no.3
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• pp.337-343
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• 2020

During the extensive forays for discovering the biodiversity of phytopathogenic fungi in Korea, powdery mildew-affected purple coneflowers (Echinacea purpurea) were frequently found. Since 2004, nine samples have been deposited in the Korea University Herbarium. The initial symptoms include white, evanescent mycelia and irregular patches on mature leaves. Mild symptoms in the form of discolored lesions are also noticed on the stem and petal of the affected plants. Based on the morphological characteristics of the anamorph and the phylogenetic analysis of the internal transcribed spacers (ITS) and large subunit (LSU) rDNA sequences, the causal fungus was identified as Podosphaera xanthii. This is the first report that identifies the causal agent of powdery mildew disease affecting purple coneflower in Korea.

• 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)

• Proceedings of the Korean Society of Plant Pathology Conference
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• 1994.06a
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• pp.50-61
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• 1994

Biological control of important fungal diseases such as Phytophthora blight of red pepper, gary mold rot of vegetables, and powdery mildew of many crops was attempted using an antagonistic bacterium, Bacillus sp. AC-1 in greenhouses and fields. The antagonistic bacterium isolated from the rhizosphere soils of healthy red pepper plant was very effective in the inhibition of mycelial growth of plant pathogenic fungi in vitro including Phytophthora capsici, Rhizoctonia solani, Pyricularia oryzae, Botrytis cinerea, Valsa mali, Fusarium oxysporum, Pythium ultimum, Alternari mali, Helminthosporium oryzae, and Colletotrichum gloeosporioides. Culture filtrate of antagonistic Bacillus sp. AC-1 applied to pot soils infested with Phytophthora capsici suppressed the disease occurrence better than metalaxyl application did until 37 days after treatment in greenhouse tests. Treatments of the bacterial suspension on red pepper plants also reduced the incidence of Phytophthora blight in greenhouse tests. In farmers' commercial production fields, however, the controlling efficacy of the antagonistic bacteria was variable depending on field locations. Gray mold rot of chinese chives and lettuce caused by Botrytis cinerea was also controlled effectively in field tests by the application of Bacillus sp. AC-1 with control values of 79.7% and 72.8%, respectively. Spraying of the bacterial suspension inhibited development of powdery mildew of many crops such as cucumber, tobacco, melon, and rose effectively in greenhouse and field tests. The control efficacy of the bacterial suspension was almost same as that of Fenarimol used as a chemical standard. Further experiments for developing a commercial product from the antagonistic bacteria and for elucidating antagonistic mechanism against plant pathogenic fungi are in progress.