• Mycobiology
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• 제42권2호
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• pp.206-209
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• 2014

In this study, we identified the causative agent of stem-end rot in potatoes that were grown in Gangwon alpine areas of Korea in 2013. The disease symptoms included appearance of slightly sunken circular lesion with corky rot on the potato surface at the stem-end portion. The fungal species isolated from the infected potatoes were grown on potato dextrose agar and produced white aerial mycelia with dark violet pigments. The conidiophores were branched and monophialidic. The microconidia had ellipsoidal to cylindrical shapes and ranged from $2.6{\sim}11.4{\times}1.9{\sim}3.5{\mu}m$ in size. The macroconidia ranged from $12.7{\sim}24.7{\times}2.7{\sim}3.6{\mu}m$ in size and had slightly curved or fusiform shape with 2 to 5 septate. Chlamydospores ranged from $6.1{\sim}8.1{\times}5.7{\sim}8.3{\mu}m$ in size and were present singly or in pairs. The causal agent of potato stem-end rot was identified as Fusarium oxysporum by morphological characterization and by sequencing the internal transcribed spacer (ITS1 and ITS4) regions of rRNA. Artificial inoculation of the pathogen resulted in development of disease symptoms and the re-isolated pathogen showed characteristics of F. oxysporum. To the best of our knowledge, this is the first study to report that potato stem-end rot is caused by F. oxysporum in Korea.

• The Plant Pathology Journal
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• 제17권2호
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• pp.110-113
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• 2001

Post-harvest diseases of kiwifruit caused severe damages on the fruits during storage, transportation, marketing and consumption. Phomopsis sp. was reported to be one of the major causal organisms of post-harvest fruit rots of kiwifruit. Symptoms of stem-end rot caused by Phomopsis sp. appeared at the stem-end area of the fruit as it ripened. The brown pubescent skin at the area became soft and lighter in color than the adjacent firm healthy tissues. A watery exudate and white mycelial mats were frequently visible at the stem-end area forming a water-drop stain down the sides on the dry brown healthy skin. When the skin was peeled back, the affected flesh tissue was usually watersoaked, disorganized, soft and lighter green than the healthy tissue. Phomopsis sp. was consistently isolated from the diseased fruits, and its pathogenicity was confirmed by an artificial inoculation test on healthy fruit of kiwifruits. The mycological characteristics of the telemorph state of the fungus produced on potato-dextrose agar were in accordance with those of Diaporthe actinidiae. This is the first report on the occurrence of a telemorph state of D. actinidiae as the causal organism of stem-end rot of kiwifruit in Korea.

• 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.

• 식물병연구
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• 제20권1호
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• pp.50-53
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• 2014

2012년 태안백합시험장 포장에 재배중인 절화 백합에서 이상증상이 발생하였다. 처음 병징은 토양 지제부의 줄기가 물러지고 점차 위쪽으로 진전되면서 결국 잎을 포함한 식물체 전체 적가 빠르게 부패되었다. 병원균의 균사생육 적온은 $25^{\circ}C$이며 PDA상에 왕성하게 생장하였으며, 갈색의 균총과 검은색의 포자낭을 형성하였다. 포자낭경은 초기에 흰색에서 점차 회색으로 되었으며 포자낭을 균사 끝에 형성하였고, 폭은 $6-10{\mu}m$이었다. 포자낭은 처음에 흰색에서 나중에 검은색으로 되었고, 모양은 반구형으로 크기는 $87-116{\mu}m$이었다. 포자낭포자는 담갈색으로 단포이며, 구형 또는 타원형으로 대부분 불규칙하며, 크기는 $4-8{\mu}m$이었다. 이상과 같이 병원균의 균학적 특징, ITS 염기서열 분석, 병원성 검정 결과 본 병해는 Rhizopus oryzae에 의한 백합 무름병으로 명명할 것을 제안한다.