• Mycobiology
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• 제36권3호
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• pp.183-189
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• 2008

The production of aerial conidia of Lecanicillium lecanii 41185, a highly virulent fungus, by solid-state fermentation was studied for use as a biocontrol agent against aphids. Among several agro-industrial solid media, steamed polished rice was found to produce the highest amount of aerial conidia. The optimal conditions for aerial conidia production were determined to be a 28.5% moisture content in the rice, 25$^{\circ}C$ culture temperature, rice pH of 6.0, 75% ambient relative humidity, 4-dold seeding culture, 0.6% $KNO_3$, and 12 d of culture time. The conidia yield increased from $5.7\times10^9$ conidia/g polished rice to 18.2 $18.2\times10^9$ conidia/g polished rice following application of these optimized conditions.

• The Plant Pathology Journal
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• 제20권3호
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• pp.165-171
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• 2004

A total of 62 isolates of Bipolaris cactivora causing cactus stem rots were isolated from major cactus-growing areas in Korea. Colony morphology of the isolates on potato-dextrose agar was differentiated into aerial (CA) and non-aerial mycelial types (CB). CA had profound aerial mycelium with grayish brown (CA-l), light brownish (CA-2), and brownish (CA-3) pigmentations; respectively, while CB had dark brownish pigmentations. CA had conidia of less dark pigmentation and acute terminal end. CB had darker and more round-end conidia. Twenty-eight amplified fragments were produced by polymerase chain reaction (PCR) with a set of 2 random primers. The sizes of amplified DNA fragments ranged approximately from 0.1 to 2.3 kb. The isolates were classified into 2 major genomic DNA random amplified polymorphic DNA (RAPD) groups at the genomic similarity of 97.7％ and 95.1％, respectively. Cluster analysis of genetic similarity among the isolates generated a dendrogram that clearly separated all isolates into SA or SB. This result suggests that there may be two morphotypes of B. cactivora in Korea that may differ in their genetic constitutes.

• International Journal of Industrial Entomology and Biomaterials
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• 제35권1호
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• pp.58-62
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• 2017

The two-spotted spider mite (Tetranychus urticae) has sustained damage on more than 200 host plants worldwide. Many farmers have relied on chemical acaricides to control mite, but the abuse of acaricides has caused serious resistance to mite. To overcome this problem, microbial control using entomopathogenic fungi have been studied. Entomopathogenic fungi have been an important role against the control of pest, and most of their culture products have been demonstrated to have virulence against pest population. In this study, we evaluated and compared the virulence of culture filtrates, aerial conidia and blastospores of selected Metarhizium anisopliae 4-2 and Beauveria bassiana 2R-3-3-1, respectively, among two-spotted spider mite-pathogenic fungi. As a result, the virulence was confirmed in all treatments, and the accumulated mortality rates were between 77 and 100% within 7 days. Especially, treatment with the fungal culture filtrate alone exhibited quite high virulence, and combined treatment with aerial conidia or blastospores enhanced activity. However, the median lethal time of treatments was not significantly different. When two isolates were compared, M. anisopliae 4-2 showed higher virulence than B. bassiana 2R-3-3-1. These results suggest that the selected two fungal isolates and their culture products could be used effectively for the control of two-spotted spider mite.

• 한국응용곤충학회지
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• 제4권
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• pp.19-24
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• 1965

Tomato 즙배지에서 도열병균의 분생포자형성 및 균사의 생장에 환경요인이 주는 영향을 연구하고자 우선 광선조사조건(광원, 조사광선의 색, 조사시간), 전배양기간, 배지의 산도 등에 관하여 조사함으로써 간편한 방법으로 단시일내에 병원균의 분생포자를 다량 생성시킬 수 있는 방법을 모색코자 본실험을 하였다. (1) 24시간 계속 형광등에 조사시킨 것이 암처리한 것이나, 주기적으로 조사한 것보다 분생포자생장 및 균사생장을 증가시켰다. (2) 무피복, 적색, 황색, 청색의 Cellophane을 투과시킨 형광등조사에서 무피복이 가장 분생포자형성이 많았고 적색 및 황색, 청색 순으로 감소하였으며 균사생장에는 유의차가 없었다. (3) 도열병균도 광선의 주기적인 조사에 의하여 광선의 색에 관계없이 수상생장을 나타냈다. (4) 전배양기간이 길수록 광선조사에 의하여 분생포자의 형성은 증가되었지만 48시간에서 가장 좋았다. (형광등구). (5) 균총의 착색정도와 공중균사의 발달정도는 분생포자형성과 밀접한 관계가 있는 것 같으며 암색일수록 분생포자의 생장은 많으며 공중균사가 많으면 분생포자생성은 감소하는 경향이 있었다. 24시간 계속조사시킨 것이 가장 암색을 나타냈고 주기적인 광선조사는 중간정도였다. (6) pH 5-9에서 분생포자 및 균사생장을 볼 수 있었는데 그 최적은 pH 7이었으며 pH4 이하의 산도에서는 전연 병균의 생장을 볼 수 없었다.

• 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.

• 한국균학회지
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• 제50권3호
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• pp.183-194
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• 2022

Two fungal strains, designated KNUF-21-006 and KNUF-21-028, were isolated from soil samples collected from Gyeongbuk Province, Korea. The strain KNUF-21-006 was similar to other Pestalotiopsis species in terms of morphological characteristics, including whitish to pale brown mycelium, conidial shape, and size. The isolate had aerial hyphae that produced black fruiting bodies on the mycelium. The conidia were fusoid to ellipsoid, four-septate, and appendage-bearing. Phylogenetic analysis using the internal transcribed spacer (ITS) region, translation elongation factor 1-alpha (TEF), and β-tubulin (TUB) gene sequences confirmed that the closest relationship of the isolate at the species level was with Pestalotiopsis clavata. The strain KNUF-21-028 exhibits similar morphological characteristics to other Botryotrichum species, including white aerial mycelium with sulcate and irregular margins, conidial shape, and size. The conidia were globose, single, and hyaline. Upon molecular analysis-using the ITS region, large subunit (LSU) rRNA gene, and TUB gene sequences-the fungus was identified as Botryotrichum iranicum. This is the first record of these fungal species in Korea.

• 한국응용곤충학회지
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• 제20권1호
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• pp.21-24
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• 1981

녹두 돌연변이계통의 갈색무늬병에 대한 저항성검정을 위하여 접종실험에 필요한 다량의 분생포자를 얻을 수 있는 배양조건 실험결과를 요약하면 다음과 같다. 1. 갈색무늬병균의 분생포자 형성에 적합한 배지는 기주식물조직배지인 녹두엽즙배지였으며 약 2500Lux의 형광조사는 분생포자 형성을 촉진시켰다. 2. 배양기상의 기중균사 거는 분생포자 형성을 현저히 증가시켜 OA배지에서도 MOA에서와 같은 량의 많은 분생포자 형성이 가능하였다. 3. 포자형성의 최적조건은 색소생성 및 균사장의 최적조건과 일치하지 않는 것으로 보였다.

• Mycobiology
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• 제47권2호
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• pp.173-179
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• 2019

Cladophialophora is characterized by simple hyphomycetes with brown hyphae that give rise to branched chains of pale brown conidia and shows affinities with the Herpotrichiellaceae. A fungal strain belonging to the genus Cladophialophora was isolated from soil in Daegu, Korea. This strain produces numerous greenish to dark black lanose aerial mycelia with hair like structures. It is morphological similar to C. chaetospira, C. inabaensis, and C. multiseptata; however, the conidiophores and conidia sizes of the newly isolated strain (KNU16-032) are clearly different from them. The novelty of the strain was also confirmed based on phylogenetic analysis using the data sets of the internal transcribed spacer region of and the partial sequence of 28S ribosomal DNA region along with the cultural characteristics. Because morphological observations and phylogenetic analysis indicated that the strain is distinct from previously known Cladophialophora species, we propose this species as a new species Cladophialophora lanosa sp. nov., and provide the detailed descriptions in this study.

• Mycobiology
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• 제45권3호
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• pp.192-198
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• 2017

The green peach aphid (Myzus persicae), a plant pest, and gray mold disease, caused by Botrytis cinerea, affect vegetables and fruit crops all over the world. To control this aphid and mold, farmers typically rely on the use of chemical insecticides or fungicides. However, intensive use of these chemicals over many years has led to the development of resistance. To overcome this problem, there is a need to develop alternative control methods to suppress populations of this plant pest and pathogen. Recently, potential roles have been demonstrated for entomopathogenic fungi in endophytism, phytopathogen antagonism, plant growth promotion, and rhizosphere colonization. Here, the antifungal activities of selected fungi with high virulence against green peach aphids were tested to explore their potential for the dual control of B. cinerea and M. persicae. Antifungal activities against B. cinerea were evaluated by dual culture assays using both aerial conidia and cultural filtrates of entomopathogenic fungi. Two fungal isolates, Beauveria bassiana SD15 and Metarhizium anisopliae SD3, were identified as having both virulence against aphids and antifungal activity. The virulence of these isolates against aphids was further tested using cultural filtrates, blastospores, and aerial conidia. The most virulence was observed in the simultaneous treatment with blastospores and cultural filtrate. These results suggest that the two fungal isolates selected in this study could be used effectively for the dual control of green peach aphids and gray mold for crop protection.

• The Plant Pathology Journal
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• 제26권4호
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• pp.346-352
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• 2010

This study was conducted in Bahar and Lalehjin, Hamadan, Iran to assess the biocontrol efficacy of Coniothyrium minitans Campbell against potato white mold caused by Sclerotinia sclerotiorum (Lib.) de Bary under field and greenhouse conditions. In addition, the resistance of common potato cultivars against S. sclerotiorum was determined in a greenhouse experiment. After straw inoculation of six potato cultivars (Pashandi, Istambouli, Agria, Marfauna, Alpha and Spartaan) with S. sclerotiorum, the least disease severity was observed in Spartaan and Marfauna. Agria showed the most susceptibility to S. sclerotiorum. Compared with the healthy control, different concentrations of C. minitans conidia ($10^7$, $10^8$ and $10^9$ conidia/mL) reduced disease severity under greenhouse condition, and a concentration $10^9$ was the most effective treatment. During 2008 and 2009, four field trials were conducted to evaluate the efficacy of C. minitans in different soil and aerial applications on disease incidence of potato white mold. In 2008, soil application of $Contans^{(R)}$ WG (a commercial product of C. minitans) showed the greatest biocontrol capacity whereas soil application of solid-substrate C. minitans was found inferior when compared with other treatments in both Bahar and Lalehjin field sites. In 2009, benomyl application was the most effective treatment in reducing disease incidence in both tested field sites.