• Proceedings of the Korean Vacuum Society Conference
• /
• 2016.02a
• /
• pp.192.1-192.1
• /
• 2016

최근 들어, 열악한 실내 공기 환경과 미세 먼지의 유입으로 아토피 피부염, 알레르기성 비염 및 천식 등의 감염성 질환이 증가하고 있다. 따라서, 공기 중 병원균(Airborne pathogens)을 친환경적으로 제거하는 기술이 요구되고 있는 추세이다. 본 연구에서 제안하는 시스템은 물을 이용하여 플라즈마를 발생시키는 시스템이다. 기존 플라즈마를 이용한 공기 정화 장치는 공기를 사용하여 플라즈마를 발생시키므로 오존과 같은 인체에 유해한 물질들이 발생되는 문제점이 있다. 하지만, 본 연구에서는 물을 사용하여 플라즈마를 발생시키므로 활성 라디칼들이 포함된 물을 미스트 형태로 분사하여 인체에 무해하며, 대기 중 병원균 살균이 가능한 장점이 있다. 물 플라즈마 젯 분사장치는 전원 공급 장치, 플라즈마 전극 그리고 플라즈마 노즐로 이루어져 있으며 주입되는 물을 기반으로 플라즈마를 발생시킨다. 장치의 특성을 분석하기 위하여, 오실로스코프로 전압 및 전류를 측정하였고 적정법을 이용하여 생성되는 활성 라디칼들의 농도를 측정하였다. 또한 살균 능력을 평가하기 위하여 병원균 중 대표적으로 대장균을 배양하여 살균 실험을 수행하였으며, 결과적으로 90% 이상의 대장균이 사멸하는 것을 확인하였다.

• The Korean Journal of Pesticide Science
• /
• v.4 no.2
• /
• pp.1-10
• /
• 2000

Fungicide resistance study in Korea is still in its infancy, and most of those resistance studies are largely limited to newness of the detected resistant strains. In future, detection of fungicide-resistant strains has to be based on sensitivity distribution of pathogen populations to certain fungicides, and standard levels of certain fungicides for resistance should be determined under the basis of this data. Most of the early research on fungicide resistance in Korea has overlooked this point, and resulted in inconsistency and confusion for monitoring sensitivity shift of pathogen population among individual researchers. Fungicide resistance detected in vitro tests has to be documented in field trials by examining control efficacy against resistant and wild-type pathogen populations. Resistance detection in wife has to be correlated with lower activity in practice. Using this process, fungicide resistance will have a practical meaning. Fitness evaluation of resistant strains for survival is, in particular, of importance to determine the future stability of the resistance in the pathogen population. In fields, sensitivity change of pathogen populations should be carefully monitored with and without fungicide selection pressures to establish long-term management strategies against fungicide resistance. It is becoming an urgent task to provide information through research for designing and implementing successful counter-measures against fungicide resistance problems in Korea.

• The Korean Journal of Pesticide Science
• /
• v.11 no.1
• /
• pp.18-26
• /
• 2007

Fungicidal screening was performed to control soybean black root rot caused by Calonectria ilicicola through in vitro and greenhouse assays. In in vitro assay, 25 fungicides were assessed by an agar dilution method and a 96-well microtiter plate method. While protective fungicides including dithianon, dichlofluanid, mancozeb, and captan showed a very low activity against the mycelial growth C. ilicicola SC03-15 in the agar dilution method, they displayed potent inhibitory activity against spore germination in a 96-well microtiter plate method with $EC_{50}$ values of 4.65, 0.61, 4.64, and $0.29{\mu}g\;mL^{-1}$, respectively. Ergosterol biosynthesis-inhibiting (EBI) fungicides showed different antifungal activity against mycelial growth and spore germination according to molecules. Difenconazole displayed higher antifungal activity against spore germination rather than mycelial growth, and prochloraz inhibited potently both mycelial growth and spore germination with EC50 values less than $1.8{\mu}g\;ml^{-1}$. In contrast, the other EBI fungicides inhibited more highly mycelial growth than spore germination. Carbendazim+diethofencarb and dazomet also inhibited both mycelial growth and spore germination of C. ilicicola SC03-15 at very low concentrations. In greenhouse assay, carbendazim+diethofencarb effectively controlled a soybean black root rot by drenching 2 days before or after inoculation. In addition, tebuconazole showed potent curative activity against soybean black root rot.

• The Korean Journal of Pesticide Science
• /
• v.10 no.3
• /
• pp.201-209
• /
• 2006

Antifungal activities of 43 different plant oils were evaluated against different phytopathogenic fungi. Thyme oil showed highest antifungal activity among the tested oils. The major of thyme oil were found to be thymol, carvacrol, bomeol, p-cymene and linalool. Thymol and carvacrol were found to be responsible for thyme's antifungal activity. The spore germination assay was conducted on Alternaria mail and Botrytis cinerea. Thymol and carvacrol strongly inhibited spore germination in the fungi test. In addition, thymol and carvacrol showed a curative effectiveness to gray mold disease on cucumber crop. The antifungal activities of alkylphenol and alkylaniline compounds, which has similar molecular structure to that of thymol or cavacrol, were also tested. It was found that alkylphenol compounds also show higher inhibition to spore germination. Thus, thymol, carvacrol and alkylphenol compounds can be used an potent antifungal agents.

• The Korean Journal of Pesticide Science
• /
• v.18 no.2
• /
• pp.115-121
• /
• 2014

This study was performed to investigate the effect of conidial density, wetness period and temperature on conidial germination, appressoria formation and disease incidence. While there was not significantly correlated between conidial density and temperature, and conidial germination and appressoria formation, there was a significant correlation between those factors and disease incidence. The longer wetness period was, the higher the ratio of conidial germination, appressoria formation and the disease incidence was. The optimum conidial density, temperature and wetness period was $1{\times}10^6$ conidia $mL^{-1}$, $30^{\circ}C$ and 5 days, respectively. In case the wetness period was more than 5 days, the typical symptom was not found on pepper fruits because of the overgrowth of mycelia. Using this fruit assay method, which the pepper anthracnose pathogens were inoculated by spraying spore suspension on non-wounded or wounded pepper fruits, control effect of three fungicides were evaluated against pepper anthracnose by the protective and/or the curative application. Propineb showed high protective control activity, while it showed curative control activity on unwounded fruits, but did not showed curative control activity on wounded fruits. Tebuconazole, one of curative fungicide, showed higher control activity in non-wound inoculation than wound inoculation. Trifloxystrobin, one of strobilurin group, showed high both protective and control activity against anthracnose. In conclusion, we supposed that the newly developed in vitro pepper fruit assay can be used to evaluate antifungal activity of control agents against pepper anthracnose.

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

• Research in Plant Disease
• /
• v.29 no.1
• /
• pp.11-22
• /
• 2023

Resazurin-based microtiter assay was used to evaluate the inhibitory effect of fungicides on the respiration of Colletotrichum acutatum s. lat. 20JDS8 sensitive and 20CDJ6 resistant to strobilurin fungicides. The spores of C. acutatum s. lat. 20JDS8 were inoculated into potato dextrose broth (PDB) at densities of 1x10⁴, 1x10⁵ and 1x10⁶ spores/ml, respectively. The relative fluorescence unit (RFU) of all treatments inoculated at each spore density started to rise after 12 hr of incubation, and were 1,965.5, 5,412.5, and 10,061.0, respectively, after 24 hr of incubation. To evaluate the inhibitory effect of fungicide on the respiration of the pathogen, the spores of the pathogen were inoculated into the PDB and treated with the fungicides 0, 6, 12, and 24 hr after incubation, respectively. After keeping the pathogen culturing for another 24 hr, PrestoBlue reagent was treated into the PDB culturing the pathogen. The RFU of each treatment was examined 1 hr after the reagent was treated. When dithianon, isopyrazam, pyraclostrobin, and fluazinam were treated at high concentrations in the stages of spores (immediately after inoculation [0 hr]), spore germination (after incubation for 6 hr), and hyphal growth (after incubation for 12 hr), the respiration of pathogens was inhibited by 90-100%. When the fungicides were treated after culturing the pathogen for 24 hr, the respiratory inhibitory effects were greatly reduced. With pyraclostrobin-resistant C. acutatum s. lat. 20CDJ6, azxoystrobin, trifloxystrobin and kresoxim-methyl, which have the same mode of action, had very little or no respiratory inhibitory effect in all growth stages of pathogens. Based on the above results, it was thought that the resazurin-based microtiter assay could quickly and accurately evaluate the inhibitory efficacy of the fungicides that inhibited respiration.

• Research in Plant Disease
• /
• v.29 no.4
• /
• pp.345-362
• /
• 2023

Anthracnose, caused by the Colletotrichum genus, comprises a significant number of plant pathogens and poses a major threat to fruit production worldwide, including South Korea. Colletotrichum species were identified associated with anthracnose in fruits such as apple, persimmon, plum, peach, jujube, walnut, and grape. A polyphasic approach, including morphology, multigene phylogenetics, and pathogenicity testing, was used. Additionally, the in-vitro sensitivity of identified Colletotrichum species to common fungicides was also evaluated. A total of nine Colletotrichum species within two complexes, namely gloeosporioides and acutatum, have been identified as the causal agents of anthracnose in common fruits in South Korea. In the gloeosporioides complex, we found Colletotrichumaenigma, C. fructicola, C. gloeosporioides, C. horii, C. siamense, and C. viniferum. Meanwhile, in the acutatum complex, C. fioriniae, C. nymphaeae, and C. orientalis were identified. Notably, C. fructicola, C. siamense, C. fioriniae, and C. nymphaeae were reported for the first time from apple, C. siamense, C. fioriniae and C. nymphaeae from plum, C. siamense, C. fructicola, and C. fioriniae frompeach, C. siamense and C. horii from persimmon, C. fioriniae from Omija (Schisandra), C. orientalis from walnut, C. nymphaeae from jujube, and C. aenigma, C. fructicola, and C. siamense fromgrape. Fungicide sensitivity tests revealed significant variation in the EC₅₀ values among specific Colletotrichum species when exposed to different fungicides. Moreover, the same Colletotrichum species isolated from different host plants displayed varying sensitivity to the same fungicide.

• The Bimonthly Magazine for Agrochemicals and Plant Protection
• /
• v.2 no.9
• /
• pp.12-23
• /
• 1981

• The Korean Journal of Pesticide Science
• /
• v.19 no.3
• /
• pp.323-328
• /
• 2015

Control efficacy was investigated with fungicides as 3 copper compound, 3 antibiotic fungicides and one fungicide containing to quinolone against the growth of Ralstonia solanacearum on NA medium and the disease occurrence on pepper seedlings. Among 7 fungicides, oxytetracycline was shown the highest activity against a growth of the pathogen in the agar diffusion method, but validamycin showed no activity against the pathogen. With $1000{\mu}g\;mL^{-1}$ of each copper fungicide as copper hydroxide, copper oxychloride+ dithianone and copper sulfate, 2.2, 1.3 and 1.5 mm in size of clear zone only could be found, respectively. In pepper seedling test, oxytetracycline showed a perfect activity in all treatments 7 days after inoculation. However, its activity was decreased from $500{\mu}g\;mL^{-1}$ of treatment over the time. Copper fungicides showed the control efficacy lower than antibiotic fungicides except for validamycin. Based on the results, it was suggested that it would be better to use antibiotic fungicides than copper fungicides to control pepper bacterial wilt in the fields.