• The Plant Pathology Journal
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• v.38 no.6
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• pp.673-678
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• 2022

Vapours from origanum oil (O) and thyme oil (T) were applied to the four soil-borne strawberry pathogens Fusarium oxysporum f. sp. fragariae, Colletotrichum fructicola, Lasiodiplodia theobromae, and Phytophthora cactorum, causing Fusarium wilt, anthracnose, dieback, and Phytophthora rot, respectively. Increasing T vapour doses in the presence of O vapour strongly inhibited mycelial growths of the four pathogens and vice versa. When mycelia of F. oxysporum f. sp. fragariae and P. cactorum exposed to the combined O + T vapours were transferred to the fresh media, mycelial growth was restored, indicating fungistasis by vapours. However, the mycelial growth of C. fructicola and L. theobromae exposed to the combined O + T vapours have been slightly retarded in the fresh media. Prolonged exposure of strawberry pathogens to O + T vapours in soil environments may be suggested as an alternative method for eco-friendly disease management.

• The Plant Pathology Journal
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• v.34 no.2
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• pp.104-112
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• 2018

Accurate and rapid detection of bacterial plant pathogen is the first step toward disease management and prevention of pathogen spread. Bacterial plant pathogens Clavibacter michiganensis subsp. nebraskensis (Cmn), Pantoea stewartii subsp. stewartii (Pss), and Rathayibacter tritici (Rt) cause Goss's bacterial wilt and blight of maize, Stewart's wilt of maize and spike blight of wheat and barley, respectively. The bacterial diseases are not globally distributed and not present in Korea. This study adopted comparative genomics approach and aimed to develop specific primer pairs to detect these three bacterial pathogens. Genome comparison among target pathogens and their closely related bacterial species generated 15-20 candidate primer pairs per bacterial pathogen. The primer pairs were assessed by a conventional PCR for specificity against 33 species of Clavibacter, Pantoea, Rathayibacter, Pectobacterium, Curtobacterium. The investigation for specificity and sensitivity of the primer pairs allowed final selection of one or two primer pairs per bacterial pathogens. In our assay condition, a detection limit of Pss and Cmn was $2pg/{\mu}l$ of genomic DNA per PCR reaction, while the detection limit for Rt primers was higher. The selected primers could also detect bacterial cells up to $8.8{\times}10^3cfu$ to $7.84{\times}10^4cfu$ per gram of grain seeds artificially infected with corresponding bacterial pathogens. The primer pairs and PCR assay developed in this study provide an accurate and rapid detection method for three bacterial pathogens of grains, which can be used to investigate bacteria contamination in grain seeds and to ultimately prevent pathogen dissemination over countries.

• The Korean Journal of Mycology
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• v.43 no.4
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• pp.207-215
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• 2015

Nanotechnology, which has become an important area of science, has caused an enormous developmental revolution in many fields. In the last two decades researchers have focused on overcoming the obstacles encountered during the preparation of nanoparticles. This article highlights the nanotechnology, along with a brief description of the manufacturing, concepts and activities of nanoparticles as alternative pesticides against plant pathogens, some methods for evaluation of nanoparticles against phytopathogens in vitro and in vivo, and explains the importance of some common nanoparticle types used in agricultural applications and plant pathology.

• Mycobiology
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• v.40 no.1
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• pp.53-58
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• 2012

This research is concerned with the fungicidal properties of nano-size silver colloidal solution used as an agent for antifungal treatment of various plant pathogens. We used WA-CV-WA13B, WA-AT-WB13R, and WA-PR-WB13R silver nanoparticles (AgNPs) at concentrations of 10, 25, 50, and 100 ppm. Eighteen different plant pathogenic fungi were treated with these AgNPs on potato dextrose agar (PDA), malt extract agar, and corn meal agar plates. We calculated fungal inhibition in order to evaluate the antifungal efficacy of silver nanoparticles against pathogens. The results indicated that AgNPs possess antifungal properties against these plant pathogens at various levels. Treatment with WA-CV-WB13R AgNPs resulted in maximum inhibition of most fungi. Results also showed that the most significant inhibition of plant pathogenic fungi was observed on PDA and 100 ppm of AgNPs.

• Korean Journal of Environmental Agriculture
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• v.31 no.1
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• pp.68-74
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• 2012

BACKGROUND: Some microorganisms extant in nature have ability to suppress various plant pathogens, and also can promote plant growth. Thus microorganisms are such great source of antimicrobial agents to develop antagonistic microorganism production and eco-friendly crop management. We isolated the microorganisms in various eco-friendly formulations. The suppressive abilities against plant pathogens have been characterized in vitro level. METHODS AND RESULTS: The indigenous microorganisms have been isolated from Cooked rice, Black sugar, Rice Bran, and Red clay using dilution plating method. Population of bacteria and fungi were above 107 in the all formulations. We isolated and pure cultured the microorganisms based on morphological characteristics. Three major plant pathogens (Fusarium oxysporum, Rhizoctonia solani, Phytophthora capsici) have been used to select antagonistic microorganisms. Total 20 bacteria and 9 fungi showed the pathogen growth suppression ability in vitro condition. The selected microorganisms were identified by ITS sequence similarity. CONCLUSION: All tested eco-friendly formulations contained high-density of the microorganisms. Among the isolated microorganisms, Bacillus spp. and Streptomyces spp. showed the most effective antifungal activity against the plant pathogens such as F. oxysporum, R. solani, and P. capsici. Among the selected fungi Trichoderma sp. demonstrated antifungal activity. Our results suggest that the currently adapted eco-friendly formulations might useful for sustain agricultural system.

• The Plant Pathology Journal
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• v.30 no.4
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• pp.397-406
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• 2014

Maize is a socioeconomically important crop in many countries. Recently, a high incidence of stalk rot disease has been reported in several maize fields in Gangwon province. In this report, we show that maize stalk rot is associated with the fungal pathogens Fusarium subglutinans and F. temperatum. Since no fungicides are available to control these pathogens on maize plants, we selected six fungicides (tebuconazole, difenoconazole, fluquinconazole, azoxystrobin, prochloraz and kresoxim-methyl) and examined their effectiveness against the two pathogens. The in vitro antifungal effects of the six fungicides on mycelial growth and colony formation were investigated. Based on the inhibition of mycelial growth, the most toxic fungicide was tebuconazole with 50% effective concentrations ($EC_{50}$) of < $0.1{\mu}g/ml$ and $EC_{90}$ values of $0.9{\mu}g/ml$ for both pathogens, while the least toxic fungicide was azoxystrobin with $EC_{50}$ values of 0.7 and $0.5{\mu}g/ml$ for F. subglutinans and F. temperatum, respectively, and $EC_{90}$ values of > $3,000{\mu}g/ml$ for both pathogens. Based on the inhibition of colony formation by the two pathogens, kresoxim-methyl was the most toxic fungicide with complete inhibition of colony formation at concentrations of 0.1 and $0.01{\mu}g/ml$ for F. subglutinans and F. temperatum, respectively, whereas azoxystrobin was the least toxic fungicide with complete inhibition of colony formation at concentrations > $3,000{\mu}g/ml$ for both pathogens.

• Korean Journal of Microbiology
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• v.43 no.3
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• pp.227-231
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• 2007

Many of antimicrobial components used in the mouthwash have disadvantages such as coloring of periodontal tissue and homing sensation. To find the more biocompatible antimicrobial agent, we have screened the 2,125 kinds of natural plant extracts obtained from by the Plant Extract Bank (Daejeon, Korea). The antimicrobial activity was determined by spectrophotometric growth inhibition assay for the major dental pathogens. For the Porphyromonas gingivalis, 19 plant extracts had an antimicrobial activity, 17 plant extracts for the Prevotella intermedia, 45 plant extracts for the Haemophilus actinomycetemcomitans and 85 plant extracts for the Streptococcus mutans. Among these effective extracts, 8 kind of natural plant extracts had an antimicrobial activity for more than 3 species of dental pathogens. In our experiment, Cudrania tricuspidata, Morus bombycis and Mallotus japonicas have antibacterial effects on the all kinds of major dental pathogens. Therefore these plant extracts have a possibility to be a candidate for major antibacterial components in dental products.

• The Plant Pathology Journal
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• v.17 no.6
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• pp.361.3-361
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• 2001

Identification of soybean sprout rot pathogens.

• The Plant Pathology Journal
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• v.38 no.4
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• pp.304-312
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• 2022

Boxwood is a representative ornamental shrub that is widely used in landscaping horticulture. After pruning, damaged leaves or stems of boxwoods are unavoidably vulnerable to infection by various plant pathogens. Several boxwood diseases caused by fungi, such as Volutella blight and Macrophoma leaf spot, have been reported worldwide including Republic of Korea. In this study, we isolated and identified fungal pathogens of boxwood diseases that occurred in Korea and characterized their morphological and taxonomic characteristics. Boxwood samples showing blight symptoms were collected in Seoul, Republic of Korea, and the putative fungal pathogens Pseudonectria buxi, P. foliicola, and Neofusicoccum buxi were successfully identified. Investigation of the morphological features of the field isolates, including mycelial growth and conidial morphology, and phylogenetic analysis of multiple DNA barcode loci revealed that there were some morphological and genetic variations among isolates, but all of the analyzed isolates were closely related to the corresponding reference strains. We also found that P. foliicola strains were more virulent than P. buxi, and the N. buxi strains isolated in this study were weak pathogens or saprophytes. The results of our study will contribute to the development of control strategies for boxwood diseases caused by fungi and accelerate research on the complex ecology of boxwood diseases.

• The Plant Pathology Journal
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• v.17 no.1
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• pp.52-56
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• 2001

This study was undertaken to separate and identify antifungla substances produced by Gilocladium virens G1, a biocontrol agent used for the control of plant diseases caused by Rhizoctonea solani. The culture of G. virens G1 effectively inhibited the growth of R. solani, Colletotrichum gloeosporioides, and Phytophthora capsici, but less that of Fusarium oxysporum. The n-hexane extract of the G. virens culture, which was used for the purification of responsible substances, strongly inhibited R. solani and C. gloeosporioides, but not P. capsici, although the n-butanol extract was effective on all of the pathogens tested. An antifungal substance was purified using the n-hexane extract by Silica gel column chromatography and HPLC. The substance was examined for purity by HPLC and for nature by UV spectrometry, which differed from known antibiotic compounds such as gliotoxin, viridin and gliovirin. The antifungal substance was very liphophilic based on its solvent-solubility and Rf values on TLC, and more inhibitory to C. gloeosporioides than other fungal pathogens tested.