• The Plant Pathology Journal
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• v.32 no.6
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• pp.528-536
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• 2016

Although many fungicides are registered for use to control powdery mildew on cucurbits, management of resistance to fungicides in pathogen populations still remains a major challenge. Two biopesticides Regalia SC and HMO 736 were evaluated in the greenhouse and field for their efficacy against powdery mildew in squash. In greenhouses, Regalia SC alone significantly (P < 0.05) reduced powdery mildew compared to the nontreated control, and was as effective as the chemical standard Procure 480SC (triflumizole). In alternation with Procure 480SC, Regalia SC demonstrated greater or equivalent effects on reducing the disease. HMO 736 alone showed varying levels of disease control, but alternating with Procure 480SC significantly improved control efficacy. In addition, application of Regalia SC or HMO 736 each in alternation with Procure 480SC significantly increased the chlorophyll content in leaves and the total fresh weight of squash plants, when compared with the water control, Regalia SC and HMO 736 alone. In field trials, application of Regalia SC and HMO 736 each alone significantly reduced disease severity in one of two field trials during the early stage of disease development, but not during later stages when disease pressure became high. Both Regalia SC and HMO 736 each applied in alternation with Procure 480SC significantly improved the control efficacy compared to Procure 480SC alone. Results from this study demonstrated that an integrated management program can be developed for powdery mildew in squash by integrating the biopesticides Regalia SC, HMO 736 with the chemical fungicide Procure 480SC.

• Korean Journal of Organic Agriculture
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• v.21 no.2
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• pp.265-270
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• 2013

Cooking oil and yolk mixture (COY) was applied to control the powdery mildew of sweet persimmon at the research field of Gyeongsangnam-do Agricultural Research and Extension Services from 2010 to 2011. COY was sprayed three times with 10 days interval on foliar parts of sweet persimmon and the disease development was monitored after 5 days of final spray. Diseased leaf area rate was 13.4% and the control efficacy of COY against powdery mildew was 80.5%. Disease rate was 68.6% on negative control. Using scanning electron microscope (SEM), the morphological changes of the powdery mildew fungus on the leaf surface were observed. On COY-treated leaves, fungal mycellia were morphologically characterized by a loss in cell volume, shriveling, plasma membrane rupture, and subsequent loss of intracellular contents. It may due to the destruction of fungal cell wall or membrane structure.

• The Korean Journal of Mycology
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• v.46 no.1
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• pp.83-90
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• 2018

Melon powdery mildew, caused by Podosphaera fusca, is one of the serious diseases of melon plant in Korea. In this study, we evaluated the effect of selected antagonistic bacteria on the inhibition of mycelial growth of various plant pathogens, and control of melon powdery mildew. Based on the 16S rDNA and gyrA gene sequences, the selected antagonistic bacteria, M09, M70, and M99-1, were identified as Bacillus velezensis. These bacteria not only inhibited the mycelial growth of 47~69% in various plant pathogens, but also significantly reduced the incidence of powdery mildew. The three strains selected in this study could be used as potential biological control agents for various plant diseases as well as melon powdery mildew.

• The Korean Journal of Mycology
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• v.22 no.3
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• pp.229-246
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• 1994

Powdery mildew fungi from 246 different species of host plants were collected at Kangwon province during 1989-1993 years. They were identified and classified into 13 genera and 83 species by examining various morphological characteristics of taxonomic value. Most of host plants were infected with one species of powdery mildew fungus, but eight plant species with two or three different mildews. Among 246 host plants collected, 43 species were added as the new host plants of powdery mildew fungi in Korea. Two Oidium spp. from Hibiscus and several Compositae plants were described to suggest their taxonomic problems.

• Research in Plant Disease
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• v.18 no.1
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• pp.49-53
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• 2012

Occurrence of powdery mildew was found on Japanese plum (Prunus salicina) growing in private gardens in Yanggu, Hongcheon, Hoengseong, and Gapyeong of central Korea, in 2011. Despite of extensive survey, however, there was no powdery mildew infection in commercial orchards of Japanese plum in Korea. The initial symptoms included white, evanescent mycelia and irregular patches on leaves and young stems. Infected leaves later showed partial distortion and diffuse red-purple discoloration. Based on morphological characteristics of holomorph and phylogenetic analysis, the causal fungus was identified as Podosphaera tridactyla. This is the first report of powdery mildew on Japanese plum in Korea.

• 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.

• Korean Journal of Agricultural Science
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• v.47 no.4
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• pp.1071-1081
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• 2020

Essential oils (EOs) have been shown to be plant-extracted antimicrobial agents. However, there are limited studies investigating the efficacy of EOs against pathogens. Among them, tea tree oil (TTO) is extracted from Melaleuca alternifolia, which is also used as an antifungal agent. In this study, the effect of TTO was investigated on the suppression of melon powdery mildew caused by Podosphaera xanthii and tomato leaf mold disease caused by Passalora fulva. Both powdery mildew and leaf mold diseases were significantly suppressed by a spray of TTO. Eighty percent of powdery mildew and 81% of leaf mold disease of the control value were suppressed by 0.5% TTO liquid, when sprayed 3 times every 7 days on the melon and tomato leaves. Inhibition of mycelial growth was also greatly affected by different concentrations of TTO against four different fungal pathogens. Ninety-eight percent of Pseudocercospora fuligena, 97% of P. fulva, 95% of Botrytis cinerea, and 94% of Phytophthora infestans mycelial growth were inhibited by 0.2% to 1.0% of TTO contained in plate media, respectively. However, phytotoxicity in plants by the TTO treatments was revealed when melon and tomato leaves were sprayed with a 1% and 2% concentration of TTO, respectively. Therefore, our findings show that TTO has high antifungal effects against various plant pathogens that occur during crop cultivation. We also suggest that when applying TTO to plant leaves, it is necessary to establish an accurate treatment concentration for different crops.

• The Korean Journal of Pesticide Science
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• v.8 no.1
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• pp.71-78
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• 2004

A promising hyperparasite, Ampelomyces quisqualis 94013(AQ94013) was selected as a biological control agent to cucumber powdery mildew caused by Sphaerotheca fusca. Effect of agrochemicals on mycelium growth and spore germination of AQ94013 and effect of spread stickers on hyperparasitical activity of AQ94013 to powdery mildew pathogen were evaluated. Finally it was confirmed that mycelial growth and spore germination of AQ94013 on potato dextrose agar amended with two fungicides for controlling powdery mildew, triadimefon and pyrazophos; five fungicides for controlling downy mildew, dimethomorph, kasugamycin+copper oxychloride, dichlofluanid+copper oxychloride and tribasic copper sulfate; three fungicides for controlling gray mold, iprodione, vinclozolin and procymidone; and six insecticides immidacloprid, teflubenzuron, bifenthrin, ethofenprox, deltamethrin and phenthoate were slightly reduced. Addition of mineral oil in the spore suspension of AQ94013 enhanced 7.9% control value to cucumber powdery mildew.

• Korean Journal of Plant Resources
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• v.10 no.4
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• pp.360-368
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• 1997

Shepherd's purse (Capsella bursa-pastoris) is one of the minor but important vegetable in Korea. The present study records 4 fungal diseases of this plant occurring under natural condition for the first time in Korea. They are white rust caused by Albugo candida, downy mildew by Peronospora parasitica, leaf spot by Pseudocercosporella capsellae, and powdery mildew by Erysiphe cichoracearum of these, white rust and downy mildew were most common causing severe damages and should be managed for the development of greenhouse cultivation of this plant.

• 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.