• Mycobiology
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• 제31권4호
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• pp.221-225
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• 2003

Effect of ethanolic extracts of Lawsonia inermis, Azadirachta indica, Vinca rosea, Tagetes patula, Ocimum sanctum, Colocasia antiquorum, Adhatoda vasica, Moringa oleifera, Datura metel and Curcuma longa leaf on conidial germination, mycelial growth and sporulation of Aspergillus flavus, A. niger and A. fumigatus were examined. The conidial germination of A. flavus and A. fumigatus were most inhibited by the extract of L. inermis, while that of A. niger was inhibited by A. indica. Other tested plant extracts have a good effect on conidial germination on the selected fungi. The highest mycelial growth of A. flavus(37 mm) was found in V. rosea, but in case of A. niger and A. fumigatus it(38 and 39 mm) was found in D. metel. The lowest(4, 9 and 6 mm) respectively mycelial growth of these fungi found in L. inermis. The highest sporulation($75{\times}10^4/ml$) of A. flavus was counted in V. rosea, but in case of A. niger and A. fumigatus those($45{\times}10^4$ and $55{\times}10^4/ml$) were in D. metel and the lowest($5{\times}10^4,\;12{\times}10^4\;and\;9{\times}10^4/ml$) respectively sporulation of these fungi counted in L. inermis plant extract medium.

• 한국식물병리학회지
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• 제13권4호
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• pp.210-214
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• 1997

포도 흰가루병균(Uncinula necutor)의 분생포자 형성, 발아 및 균사 초기생장에 미치는 중요 환경오인과 살균제의 영향을 구명하기 위하여 수행한 연구 결과를 요약하면 다음과같다. 분생포자 형성은 상대습도 76~96%에서 가장 좋았다. 포자 발아 및 균사 초기생장은 증류수에 비해 5% 한천배지에서 좋았으며, 온도 $26^{\circ}C$, pH 5.0일 때 가장 좋았다. 광 100 lux는 암상태와 발아율에 차이가 없었으며 한천배지에 포도 엽즙액 30%를 첨가한 배지에서는 순수 한천배지 보다 좋았다. 또 triazole계 살균제 첨가 배지에서의 포자발아 및 균사생장은 살균제 농도증가에 비례하여 급격히 감소하였으나 그 정도는 살균제의 종류에 따라 차이가 있었다. 특히, myclobutanil은 농도증가에 따른 발아율의 감소정도가 매우 낮았다.

• The Plant Pathology Journal
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• 제18권1호
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• pp.50-53
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• 2002

To develop Epicoccosorus nematosporus as a mycoherbicide of Eleocharis kuroguwai, the optimum temperature and humidity for sporulation of the pathogen were studied. Conidial production was most abundant at $28^{\circ}C$ with RH 60%, which yielded 661 mg in 9 cm Petri dish. Light intensity of 3,000 up to 7,500 lux was effective in stimulating conidial production of E. nematosporus on oatmeal agar, Light intensity affected sporulation more significantly than temperature. In the pot test, at least 12 h of dew period at $20^{\circ}C$ and $25^{\circ}C$ was required to achieve satisfactory conidial germination and appressorial formation. Few were killed at 8 h of dew period regardless of temperature. Sixteen hours of a single dew treatment immediately after inoculation killed more plants than did two or three repetitive dew treatments of 8-12 h.

• The Plant Pathology Journal
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• 제16권4호
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• pp.206-210
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• 2000

The effect of the electrolyzed oxidizing water on Sphaerotheca fuliginea was investigated with germination and sporulation of the fungal conidia. The sporulation was inhibited by the electrolyzed oxidizing water of pH 2.5, 3.5, and 4.5, but was not inhibited by the distilled water adjusted pH with 1N-HCL solution. However, the electrolyzed oxidizing water did not affect conidial germination. The oxidation-reduction potential at pH 2.5 and pH 3.5 of electrolyzed oxidizing water were 1130 mV and 1060 mV, respectively, but those of distilled water adjusted with HCL solution were 550 mV and 490 mV, respectively. When the electrolyzed oxidizing water of ORP over 1100 mV was sprayed on cucumplanting, the disease severities of powdery mildew were about 8.5% and 19.2%, respectively. Disease severity of a standard control (triflumizole 30% WP, $500\textrm{mg}\textrm{/L}$) was about 3.0%, while that of plants without electrolyzed oxidizing water was to 45.8%.

• Mycobiology
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• 제46권1호
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• pp.52-63
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• 2018

In our previous studies, Bacillus megaterium KU143, Microbacterium testaceum KU313, and Pseudomonas protegens AS15 have been shown to be antagonistic to Aspergillus flavus in stored rice grains. In this study, the biocontrol activities of these strains were evaluated against Aspergillus candidus, Aspergillus fumigatus, Penicillium fellutanum, and Penicillium islandicum, which are predominant in stored rice grains. In vitro and in vivo antifungal activities of the bacterial strains were evaluated against the fungi on media and rice grains, respectively. The antifungal activities of the volatiles produced by the strains against fungal development and population were also tested using I-plates. In in vitro tests, the strains produced secondary metabolites capable of reducing conidial germination, germ-tube elongation, and mycelial growth of all the tested fungi. In in vivo tests, the strains significantly inhibited the fungal growth in rice grains. Additionally, in I-plate tests, strains KU143 and AS15 produced volatiles that significantly inhibited not only mycelial growth, sporulation, and conidial germination of the fungi on media but also fungal populations on rice grains. GC-MS analysis of the volatiles by strains KU143 and AS15 identified 12 and 17 compounds, respectively. Among these, the antifungal compound, 5-methyl-2-phenyl-1H-indole, was produced by strain KU143 and the antimicrobial compounds, 2-butyl 1-octanal, dimethyl disulfide, 2-isopropyl-5-methyl-1-heptanol, and 4-trifluoroacetoxyhexadecane, were produced by strain AS15. These results suggest that the tested strains producing extracellular metabolites and/or volatiles may have a broad spectrum of antifungal activities against the grain fungi. In particular, B. megaterium KU143 and P. protegens AS15 may be potential biocontrol agents against Aspergillus and Penicillium spp. during rice grain storage.

• The Plant Pathology Journal
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• 제16권1호
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• pp.19-24
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• 2000

The direct effects of acute $\textrm{O}_3$ on the growth, sporulation and infection of Pyricularia grisea, rece blast pathogen, were investigated to understand the interactions between ozone and the pathogen. Acute exposure of 200 nl $\textrm{l}^{-1}$ ozone for 8 h significantly reduced conidia germination on water atar. Ozone exposure of 200 nl $\textrm{l}^{-1}$ for 8h per day for 5 days had no effect on increase in colony diameter, but severely damaged actively growing aerial mycelia. However, the damage to mycalia was recovered during the following 16 h exposure of unpolluted air. Conidial production was also stimulated by the acute ozone exposure for 5 days. The conidia exposed to the acute ozone for 5 days normally germinates but slightly reduce appressoria formation on rice leaf. However, the conidia produced by artificial stimulation under the same ozone concentration for 10 days showed significant reduction in appressorea for mation on a hydrophobic film. This study suggests that the acute ozone could ingibit appressoria formation as well as vegetative growth of the pathogen, resulting in decrease in rece blast development in the field during summer when high ozone episodes could occur occasionally.

• 농약과학회지
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• 제4권3호
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• pp.68-74
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• 2000

Penicillium oxalicum (PENOX)은 잔디밭 토끼풀(Trifolium repens L.)의 방제를 위한 생물제제(biocontrol agent, BCA)로서의 잠재성을 보여왔다. 미생물제초균류에 의한 제초활성은 다양한 환경조건하에서 이들의 발아율, 생장력 및 기질이용성 등에 크게 영향을 받는다. 따라서 본 연구는 PENOX의 다양한 수분확성($0.94{\sim}0.995\;a_w$) 및 온도조건($18{\sim}30^{\circ}C$)하에서의 균사생장, 포자발아율 및 포자생성량을 glycerol로 조정된 MEA(malt extract agar) 배지를 사용하여 in vitro상에서 조사하였다. PENOX의 균사생장은 높은 수분활성조건($0.995\;a_w$)에서 가장 좋았으며 $30^{\circ}C$에서 가장 양호하였다. 또한 $0.995\;a_w$에서는 저온($20^{\circ}C$)에서도 균사생장이 대체로 양호하여 수분활성이 약간 낮은 조건($0.97\;a_w$)에서의 최대 균사생장율과 비슷한 균사생장율을 나타냈다. $0.97\;a_w$에서의 균사생장율은 $25^{\circ}C$와 $30^{\circ}C$조건간에 대체로 비슷한 결과를 나타냈으며 저온($20^{\circ}C$)에서는 매우 감소하였다. PENOX의 포자발아율도 $0.995\;a_w/30^{\circ}C$에서 가장 높았으며 수분활성이 감소할수록 낮아지는 경향을 나타냈다. 저온($18^{\circ}C$)에서의 발아전 지체시간(lag phase time)은 전 $a_w$ 조건하에서 6시간 이상 그리고 낮은 수분활성조건($0.94\;a_w$)하에서는 18과 $25^{\circ}C$에서 각 18, 12시간 이상으로 나타났다. 그러나 포자생성은 $0.995\;a_w$의 높은 수분조건에 비해 약간 낮은 $0.97\;a_w$ 조건에서, 그리고 고온($30^{\circ}C$)에 비해 저온조건($20^{\circ}C$) 하에서 훨씬 양호하였다. 한편, GN MicroPlate를 이용해 PENOX의 기질로서의 95개 탄소원에 대한 이용성을 조사한 결과 $0.995\;a_w/25^{\circ}C$에서의 생태적 생식역값(niche size)은 86으로 가장 높았으며 수분스트레스조건($0.955\;a_w$)에서는 그 이용성이 낮아져 그 값은 65를 나타냈다. 그리고 고온($30^{\circ}C$)에서는 $0.995\;a_w$ 및 $0.955\;a_w$에서는 각각 84와 50을 나타내 $0.995\;a_w$에서 보다 $0.955\;a_w$ 조건에서 탄소원 이용시 온도스트레스에 더 민감하게 반응하는 것으로 나타났다. 이러한 균류생태생리학적인 정보는 효과적인 BCA의 개발을 위한 기초자료로서 유용하게 활용될 수 있을 것이다.

• Mycobiology
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• 제45권3호
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• pp.213-219
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• 2017

In our previous study, three bacterial strains, Bacillus megaterium KU143, Microbacterium testaceum KU313, and Pseudomonas protegens AS15, were selected as effective biocontrol agents against Aspergillus flavus on stored rice grains. In this study, we evaluated the inhibitory effects of the volatiles produced by the strains on A. flavus growth and aflatoxin production on stored rice grains. The three strains significantly reduced mycelial growth of A. flavus in dual-culture assays compared with the negative control strain, Sphingomonas aquatilis KU408, and an untreated control. Of these tested strains, volatiles produced by B. megaterium KU143 and P. protegens AS15 markedly inhibited mycelial growth, sporulation, and conidial germination of A. flavus on agar medium and suppressed the fungal populations in rice grains. Moreover, volatiles produced by these two strains significantly reduced aflatoxin production in the rice grains by A. flavus. To our knowledge, this is the first report of the suppression of A. flavus aflatoxin production in rice grains using B. megaterium and P. protegens volatiles.

• 농업과학연구
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• 제15권1호
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• pp.9-14
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• 1988

백합(百合) 잎마름병균(病菌)(Botrytis elliptica)의 균사생장(菌絲生長), 포자형성(胞子形成) 및 균핵형성(菌核形成)에 미치는 주요(主要)한 환경요인(環境要因)의 영향(影響)을 밝히고자 실험(實驗)을 실시(實施)한 결과는 다음과 같다. 1. B. elliptica는 V-8 juice agar 배지(培地)에서 균사생장(菌絲生長)이 가장 양호(良好)하였으며 NUV light 조사시(照射時) 다른 배지(培地)에 비해 분생포자(分生胞子)의 형성(形成)도 빨랐고 형성량(形成量)도 많았으며 3일간(日間) $23^{\circ}C$에 배양(培養)한 후 NUV light를 조사(照射)하면 보다 다량(多量)의 분생포자(分生胞子)를 얻을 수 있었다. 2. 균(菌)의 생장(生長) 및 포자발아적온(胞子發芽適溫)은 $23^{\circ}C$였으며 고온(高溫)보다는 $19{\sim}23^{\circ}C$의 비교적(比較的) 저온(低溫)에서 균(菌)의 생장(生長)이 빨랐다. 3. pH 4.5~5.0에서 균(菌)의 생육(生育)이 좋았으나 pH가 높아질수록 생장(生長)이 억제(抑制)되었다. 4. 광(光)은 균사(菌絲)의 생육(生育)에는 큰 영향이 없었으나 포자(胞子)의 형성(形成)에는 광(光)의 종류(種類)가 매우 크게 작용(作用)하여 NUV light 조사(照射)에 의(依)해서만 분생포자(分生胞子)가 형성(形成)되었다. 균핵(菌核)은 $19^{\circ}C$이하(以下)의 배양(培養)에서만 형성(形成)되었다.