• Research in Plant Disease
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• v.15 no.1
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• pp.13-16
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• 2009

In April 2008, cherry (Prunus yedoensis Matsumura) in Jeju exhibited severe disease of branches forming numerous twigs. Five isolates from diseased leaves were identified as Taphrina wiesneri on the basis of biological and genetic characteristics. Twenty one commercial fungicides were tested for control of the disease in vitro. Of the 21 fungicides, triazole compounds (difenoconazole, propiconazole and tebuconazole) showed relatively good antimicrobial activities. Results from the planta bioassays indicated that triazole compounds reduced the witches' broom disease showing control value $25.7{\sim}52.8%$ compared with the nontreated controls.

• Mycobiology
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• v.50 no.1
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• pp.79-85
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• 2022

Strawberries are a popular economic crop, and one of the major plantations and exporting countries is Korea in the world. The Fusarium oxysporum species complex (FOSC) is a soil-borne pathogen with genetic diversity, resulting in wilt disease in various crops. In Korea, strawberries wilt disease was first reported in the 1980s due to the infection of FOSC, causing significant economic damage every year. The causal agent, F. oxysporum f. sp. fragariae, is a soil-borne pathogen with a characteristic of FOSC that is difficult to control chemically and mutates easily. This study obtained genetic polymorphism information that was based on AFLP, of F. oxysporum f. sp. fragariae 91 strains, which were isolated from strawberry cultivation sites in Gyeongsangnam-do and Chungcheongnam-do, and compared strains information, which was the isolated location, host variety, response to chemical fungicide, and antagonistic bacteria, and mycelium phenotype. As a result, AFLP phylogeny found that two groups were mainly present, and group B was present at a high frequency in Gyeongsangnam-do. Group B proved less sensitive to tebuconazole than group A through Student's t-test. In addition, the fractions pattern of AFLP was calculated by comparing the strain information using PCA and PERMANOVA, and the main criteria were separated localization and strawberry varieties (PERMANOVA; p< 0.05). And tebuconazole was different with weak confidence (PERMANOVA; p< 0.10). This study suggests that the F. oxysporum f. sp. fragariae should be continuously monitored and managed, including group B, which is less chemically effective.

• Mycobiology
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• v.51 no.4
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• pp.264-272
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• 2023

Onion (Allium cepa L.) is an economically important vegetable crop worldwide. However, various fungal diseases, including Fusarium basal rot (FBR), neck rot, and white rot, reduce onion production or bulb storage life. FBR caused by Fusarium species is among the most destructive onion diseases. In this study, we identified Fusarium species associated with FBR in Jeolla and Gyeongsang Provinces in South Korea and evaluated fungicides against the pathogens. Our morphological and molecular analyses showed that FBR in onions is associated with Fusarium commune, Fusarium oxysporum, and Fusarium proliferatum. We selected seven fungicides (fludioxonil, hexaconazole, mandestrobin, penthiopyrad, prochloraz-manganese, pydiflumetofen, and tebuconazole) and evaluated their inhibitory effects on mycelial growth of the pathogens at three different concentrations (0.01, 0.1, and 1 mg/mL). We found that prochloraz-manganese was highly effective, inhibiting 100% of the mycelial growth of the pathogens at all concentrations, followed by tebuconazole. Fludioxonil showed < 50% inhibition at 1 mg/mL for the tested isolates.

• Korean Journal of Environmental Agriculture
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• v.37 no.1
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• pp.34-40
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• 2018

BACKGROUND: In order to select a fungicide that can effectively control anthracnose disease in Japanese plum fruit, mycelial growth inhibition effect and spore germination inhibition effect of six fungicides were tested in vitro against six isolates of Colletotrichum acutatum and five isolates of C. gloeosporioides that were isolated from diseased Japanese plum fruit. METHODS AND RESULTS: Inhibitory effects of fungicides on mycelial growth were investigated after inoculating each isolate on potato dextrose agar amended with four discriminatory concentrations of each fungicide for 7 days at $25^{\circ}C$. For spore germination inhibitory effect, each isolate of the Colletotrichum spp. was cultured in potato dextrose agar for 7-14 days at $25^{\circ}C$. After adjusting the concentration of spores of each isolate to $1{\times}10^6mL^{-1}$ by diluting with 0.025% PDB, the spore suspension was mixed with each fungicide (1:4, v/v), and $60{\mu}L$ aliquots were dispensed to sterile hole slide glass. Hole slide glasses were placed in a humidified box and incubated for 15 hours at $25^{\circ}C$. Then, spore germination was observed under an optical microscope. At recommended concentration of fungicide prochloraz manganese showed the highest mycelial growth inhibitory effect and dithianon showed the lowest mycelial growth inhibition. The $EC_{50}$ values for the inhibition of spore germination by dithianon and pyraclostrobin were $0.069-0.126{\mu}g/mL$ and $0.37-1.59{\mu}g/mL$, respectively. Although benomyl, prochloraz manganese, azoxystrobin, and tebuconazole did not inhibit the spore germination, they appeared to restrain mycelial growth by abnormal growth of germ tube and mycelium after germination. CONCLUSION: Dithianon seemed to have preventive effect. Prochloraz manganese, azoxystrobin, and tebuconazole were likely to have control effect. Pyraclostrobin is considered to have both preventive and control effect against anthracnose disease of Japanese plum fruit.

• The Korean Journal of Pesticide Science
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• v.17 no.2
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• pp.133-139
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• 2013

To investigate the sensitivity of Sclerotium cepivorum causing garlic white rot to 5 fungicides, including prochloraz, tebuconazole, flutolanil, iminoctadine and isoprothiolane, 147 isolates isolated from infected garlics from 2008 to 2009 through a single sclerotium isolation were screened. While each mean value of $EC_{50}$ (effective concentration reducing mycelial growth by 50%) of S. cepivorum isolates collected in 2008 to each fungicide was 0.054, 0.012, 23.189, 0.901, and $21.362{\mu}g\;mL^{-1}$, that of 2009 isolates were 0.030, 0.020, 10.367, 1.684, $33.406{\mu}g\;mL^{-1}$. There was a difference in mean value of $EC_{50}$ of S. cepivorum according to regions isolated. $EC_{50}$ values of S. cepivorum isolated in Goheung to flutolanil and isoprothiolane were 14.468 and $24.653{\mu}g\;mL^{-1}$, respectively, which was lower than those of Seosan and Taeahn. Isolates from Taeahn showed the lowest $EC_{50}$ value to prochloraz as $0.008{\mu}g\;mL^{-1}$. In addition, we could not find any resistant isolates to fungicides tested. The $EC_{50}$ values in this study will be used in a fungicide resistance monitoring program to determine whether shifts in sensitivity to fungicides included into different groups are occurring in S. cepivorum populations.

• Journal of Korean Society of Forest Science
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• v.105 no.4
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• pp.505-509
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• 2016

This study was conducted to examine the effectiveness of various dressing materials applied to tree wounds in Korea. Significantly higher wound closure rates than those of controls were found when thiophanatemethyl paste (Topsin Paste$^{(R)}$) was applied to Ginkgo biloba, Zelkova serrata, and Prunus yedoensis; lanolin to Z. serrata and P. yedoensis; and tebuconazole paste (Silvacur$^{(R)}$) to P. yedoensis. However, significantly lower wound closure rates than those of controls were found when petroleum jelly (Vaseline$^{(R)}$) was applied to G. biloba, Z. serrata, and P. yedoensis. It was noted that the wounds of Z. serrata and P. yedoensis treated with petroleum jelly expanded due to the death of cambium located at the edge of the wounds. Wound closure rates applied with adhesive - non-toxic to human body (Okong bond$^{(R)}$) were also significantly lower than those of controls in Z. serrata. Pinus densiflora showed no reaction to any experimental wound dressing because of resin secreted from the exposed cambium.

• 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.

• The Plant Pathology Journal
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• v.33 no.6
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• pp.589-596
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• 2017

Chemical management of dollar spot in turf may lead to the development of Sclerotinia homoeocarpa populations with reduced fungicide sensitivity. The objective of this study was to investigate resistance of S. homoeocarpa isolates to triazole fungicides and to test cross-resistance among three triazole fungicides. A total of 66 isolates of S. homoeocarpa were collected from 15 golf courses across Korea, and tested via in vitro sensitivity assay against hexaconazole, propiconazole and tebuconazole. $EC_{50}$ values of the isolates to these fungicides were distributed in the range of $0.001-1.1\;a.\;i.\;{\mu}g\;ml^{-1}$. Based on the $EC_{50}$ values, twelve representative strains were selected as sensitive isolates including control and insensitive isolates with respect to each fungicide. At a concentration of $0.1\;a.\;i.\;{\mu}g\;ml^{-1}$ for all fungicides, the selected strains were distinguished as sensitive or resistant isolates with the mycelial growth inhibition rate of 50% as the criterion. The $EC_{50}$ values of resistant strains exposed to hexaconazole, propiconazole and tebuconazole were 20-50 times, 50-70 times, and 77 times greater, respectively, than that of the control strains. Two isolates of S. homoeocarpa S0-41 and Sh14-2-1 showed sensitivity toward all the fungicides used, while two other isolates Sh7-5-1 and Sh2-1-1 showed resistance to all fungicides. Each isolate showed similar resistance to the three types of triazole fungicides, whereby cross-resistance of isolates was confirmed in the present study; all three triazole fungicide combinations displayed significant correlation coefficients equivalent to or greater than 0.8.

• The Korean Journal of Pesticide Science
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• v.20 no.2
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• pp.165-171
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• 2016

Platycodon grandiflorum and Codonopsis lanceolata have been considered as cash vegetables and alternative medicine plants in Korea. In a previous survey from 1998 to 2010, repeated cultivation of the plant increased root rot disease incidence and severity. The disease has been recognized as critically limiting factor for crop production. However, control method has not been established for the disease of P. grandiflorum and C. lanceolata. In this study, control efficacy of Tebuconazole EC, Trifloxystroim SC and grapefriut extract was evaluated on the root rot disease of these plants in two different field conditions. Three of different fungicide were non critical effect to the disease severity and the control value, but grapefriut seed extract (GSE) was more ability to control the disease in C. lanceolata. In most things, soil drainage was the most important to decrease the disease severity and to improve the control value.

• Korean Journal of Microbiology
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• v.37 no.4
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• pp.305-311
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• 2001

Antifungal bacterium, Bacillus subtilis YS1 was isolated from Yusong hot spring showed broad antifungal spectrum against 12 kinds of plant pathogenic fungi and Candida albicans, animal pathogen. From the gamma($Co^{60}$) radiation sensitivity test, $D_10$ value was 2.08 kGy and it survived above 20 kGy of radiation dose. Several mutants were induced by gamma radiation. Among them, YS1-1009 mutant showed resistance against tebuconazole of herbicide, increased activity against Botryoshaeria dothidea and ligninase activity. YS67 mutant was antifungal deficient auxotrophic mutants(trp-pro-or arg-ura-). From this results, it suggested that gamma irradiation could be useful method for mutant induction.