• 식물병연구
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• 제27권4호
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• pp.164-171
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• 2021

2020년 8월에 전라북도 순창군 소재 25개 고추 재배지에서 채집한 탄저병 감염 과실로부터 377개 탄저병균주를 분리한 후 지역별로 선발된 62개 균주를 대상으로 국내에 등록된 11개의 고추 탄저병 살균제에 대한 균사생장억제율을 조사하여 각각의 살균제에 대한 감수성 정도를 조사하였다. 살균제에 대한 탄저병균의 살균제 감수성 실험 결과 fluazinam, prochloraz manganese, benomyl에서는 저항성 균주가 관찰되지 않았으나 이외의 약제에서는 최소 3개의 지역에서 저항성 균주가 출현하였으며, dithianon은 모든 지역의 모든 균주가 저항성이었다. 이를 통해 일부 지역에서 살균제의 지속적인 처리로 인하여 균주집단 내 살균제 내성이 발현되었음을 확인할 수 있었다. 지역별로는 순창읍과 팔덕면에서 7개 농약에 대한 저항성 균주가 출현하였고, 금과면, 복흥면, 쌍치면, 유등면, 풍산면에서 6개 농약에 대한 저항성 균주가 출현하였음을 확인하였다. 약제 등록시기와 저항성 균주의 출현에는 유의미한 상관관계가 없었다.

• The Plant Pathology Journal
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• 제25권4호
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• pp.317-321
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• 2009

Sensitivity to the new carboxylic acid amide fungicide, mandipropamid, of Phytophthora capsici causing pepper Phytophthora blight was determined on 187 isolates collected in Korea over 3 years, from 2005 to 2007. All isolates were sensitive to mandipropamid, with $EC_{30}$ values for growth of mycelia ranging from 0.001 to $0.037\;{\mu}g/ml$. Among the isolates, 147 (79.0%) isolates were sensitive to metalaxyl, whereas others were resistant to this fungicide. Mandipropamid had the same effect on mycelium growth of both metalaxyl-sensitive and metalaxyl-resistant isolates, indicating an absence of cross-resistance between these two fungicides. Comparison of the sensitivities of P. capsici isolates showed a positive correlation between sensitivity to mandipropamid and dimethomorph ($r^2$=0.8533). The results of this study indicate that there is no evidence for development of resistance to mandipropamid in this population of P. capsici isolates collected in Korea.

• The Plant Pathology Journal
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• 제33권2호
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• pp.118-124
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• 2017

Bell pepper is an economically important crop worldwide; however, production is restricted by a number of fungal diseases that cause significant yield loss. Chemical control is the most common approach adopted by growers to manage a number of these diseases. Monitoring for the development to resistance to fungicides in pathogenic fungal populations is central to devising integrated pest management strategies. Two fungal species, Fusarium incarnatum-equiseti species complex (FIESC) and Colletotrichum truncatum are important pathogens of bell pepper in Trinidad. This study was carried out to determine the sensitivity of 71 isolates belonging to these two fungal species to fungicides with different modes of action based on in vitro bioassays. There was no significant difference in log effective concentration required to achieve 50% colony growth inhibition ($LogEC_{50}$) values when field location and fungicide were considered for each species separately based on ANOVA analyses. However, the $LogEC_{50}$ value for the Aranguez-Antracol locationfungicide combination was almost twice the value for the Maloney/Macoya-Antracol location-fungicide combination regardless of fungal species. $LogEC_{50}$ values for Benomyl fungicide was also higher for C. truncatum isolates than for FIESC isolates and for any other fungicide. Cropping practices in these locations may explain the fungicide sensitivity data obtained.

• The Plant Pathology Journal
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• 제15권6호
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• pp.340-344
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• 1999

Fungicide-resistant isolates of Monilinia fructicola grew readily on media amended with 0.1, 1.0, 10, 100 and $1,000\mu\textrm{g}$ a.i./ml of carendazim, benomyl, or thiophanate-methyl. However, sensitive isolates did not grow on media amended even with $0.1\mu\textrm{g}$ a.i./ml of carbendazim, $1.0\mu\textrm{g}$ a.i./ml of benomyl or thiophanate-methyl. The fitness compositions including mycelial growth on fungicide-free medium, sporulation on fungicide-free medium and pear, and virulence on pear were not different between resistant and sensitive isolates. The resistant isolates persisted carbendazim resistance during multiple subdulturing and long term storage. The competitive ability of resistant isolates obtained from peach orchards in Korea was similar to those of sensitive isolates.

• 식물병연구
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• 제24권1호
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• pp.59-65
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• 2018

Pyraclostrobin은 광범위한 스펙트럼의 항진균 활성이 있는 퀴논외부저해제(Quinone outside inhibitor, QoI)로 작용하는 살균제이다. 기존 보고에 의하면 pyraclostrobin이 일부 세균병과 바이러스병에 대해 병 저항성을 유도한다고 알려져 있다. 본 연구는 pyraclostrobin 항진균제를 활용하여 고추 세균점무늬병(Xanthomonas euvesicatoria)의 예방 가능성을 검토하였다. Pyraclostrobin은 in vitro 상에서 X. euvesicatoria에 대해 항균활성이 없었지만, 고추에 pyraclostrobin 단독(방제가 69%) 또는 streptomycin과 혼합 살포(방제가 90%) 하였을 때, 고추 세균점무늬병 예방 효과를 나타냈다. Pyraclostrobin의 고추 세균점무늬병 예방 효과는 병원균 접종 1-3일전이 효과적이었다. 이상의 결과로 pyraclostrobin 살진균제를 활용하여 고추 세균점무늬병을 효과적으로 예방할 수 있을 것을 사료된다.

• The Plant Pathology Journal
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• 제33권6호
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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 Plant Pathology Journal
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• 제31권2호
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• pp.115-122
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• 2015

Anthracnose, caused by Colletotrichum gloeosporioides (C. gloeosporioides; Teleomorph: Glomerella cingulata), is the most destructive disease that affects sweet persimmon production worldwide. However, the biology, ecology, and genetic variations of C. gloeosporioides remain largely unknown. Therefore, in this study, the development of fungicide resistance and genetic diversity among an anthracnose pathogen population with different geographical origins and the exposure of this population to different cultivation strategies were investigated. A total of 150 pathogen isolates were tested in fungicide sensitivity assays. Five of the tested fungicides suppressed mycelial pathogen growth effectively. However, there were significant differences in the sensitivities exhibited by the pathogen isolates examined. Interestingly, the isolates obtained from practical management orchards versus organic cultivation orchards showed no differences in sensitivity to the same fungicide. PCR-restriction fragment length polymorphism (RFLP) analyses were performed to detect internal transcribed spacer regions and the ${\beta}$-tubulin and glutamine synthetase genes of the pathogens examined. Both the glutamine synthetase and ${\beta}$-tubulin genes contained a complex set of polymorphisms. Based on these results, the pathogens isolated from organic cultivation orchards were found to have more diversity than the isolates obtained from the practical management orchards.

• The Plant Pathology Journal
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• 제33권1호
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• pp.95-100
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• 2017

Fungicide-resistant Alternaria alternata impede the practical control of the Alternaria diseases in crop fields. This study aimed to investigate cytological fungicide resistance mechanisms of A. alternata against dicarboximide fungicide iprodione. A. alternata isolated from cactus brown spot was cultured on potato-dextrose agar (PDA) with or without iprodione, and the fungal cultures with different growth characteristics from no, initial and full growth were observed by light and electron microscopy. Mycelia began to grow from one day after incubation (DAI) and continued to be in full growth (control-growth, Con-G) on PDA without fungicide, while on PDA with iprodione, no fungal growth (iprodione-no growth, Ipr-N) occurred for the first 3 DAI, but once the initial growth (iprodione-initial growth, Ipr-I) began at 4-5 DAI, the colonies grew and expanded continuously to be in full growth (iprodione-growth, Ipr-G), suggesting Ipr-I may be a turning moment of the morphogenetic changes resisting fungicidal toxicity. Con-G formed multicellular conidia with cell walls and septa and intact dense cytoplasm. In Ipr-N, fungal sporulation was inhibited by forming mostly undeveloped unicellular conidia with degraded and necrotic cytoplasm. However, in Ipr-I, conspicuous cellular changes occurred during sporulation by forming multicellular conidia with double layered (thickened) cell walls and accumulation of proliferated lipid bodies in the conidial cytoplasm, which may inhibit the penetration of the fungicide into conidial cells, reducing fungicide-associated toxicity, and may be utilized as energy and nutritional sources, respectively, for the further fungal growth to form mature colonies as in Ipr-G that formed multicellular conidia with cell walls and intact cytoplasm with lipid bodies as in Con-G.

• The Plant Pathology Journal
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• 제38권6호
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• pp.616-628
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• 2022

Resistance to pyraclostrobin due to a single nucleotide polymorphism at 143rd amino acid position on the cytochrome b gene has been a major source of concern in red pepper field infected by anthracnose in Korea. Therefore, this study investigated the response of 24 isolates of C. acutatum and C. gloeosporioides isolated from anthracnose infected red pepper fruits using agar dilution method and other molecular techniques such as cytochrome b gene sequencing, polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and allele-specific polymerase chain reaction (PCR). The result showed that four isolates were resistant to pyraclostrobin on agar dilution method and possessed GCT (alanine) codon at 143rd amino acid position, whereas the sensitive isolates possessed GGT (glycine). Furthermore, this study illustrated the difference in the cytochrome b gene structure of C. acutatum and C. gloeosporioides. The use of cDNA in this study suggested that the primer Cacytb-P2 can amplify the cytochrome b gene of both C. acutatum and C. gloeosporioides despite the presence of various introns in the cytochrome b gene structure of C. gloeosporioides. The use of allele-specific PCR and PCR-RFLP provided clear difference between the resistant and sensitive isolates. The application of molecular technique in the evaluation of the resistance status of anthracnose pathogen in red pepper provided rapid, reliable, and accurate results that can be helpful in the early adoption of fungicide-resistant management strategies for the strobilurins in the field.

• The Plant Pathology Journal
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• 제17권4호
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• pp.205-209
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• 2001

Dicarboximide-resistant isolates of Monilinia fructicola grew readily on media amended with dicarbosimide fungicides, and showed cross-resistance to pentachlo-ronitrobenzene (PCNB). The fitness of resistant isolates was inferior to that of sensitive isolates. Mycelial growth on fungicide-free medium was not significantly different between the dicarboximide-resistant and sensitive isolates. The originally high $\textrm{EC}_{50}$ values of the resistant isolate decreased after storage for 16 weeks at $4^{\circ}$. After inoculation with the mixture of spore suspensions of resistant and sensitive isolates, the re-isolation rate of the resistant spores was significantly reduced regardless of the mixing ratio. From the results, it could be concluded that the competitive ability of the resistant isolates is inferior to the sensitive ones.