• Mycobiology
• /
• 제40권3호
• /
• pp.214-216
• /
• 2012

Soft rot on banana fruit caused by Rhizopus oryzae was identified for the first time in Korea. Colonies were white to light brown and formed numerous sporangiospores. Optimum temperature for mycelial growth was $30^{\circ}C$. Sporangia were globose and $30{\sim}200{\mu}m$. Sporangiophores were usually straight, $8{\sim}20{\mu}m$, and rhizoids usually in groups of 3~5. Columella were globose to sub-globose and $90{\sim}110{\mu}m$. Sporangiospores were sub-globose or oval and $4{\sim}10{\mu}m$. Based on its mycological characteristics, molecular analysis, and pathogenicity to host plants, this fungus was identified as Rhizopus oryzae Went & Prisen Geerligs. This is the first report of soft rot on banana caused by Rhizopus oryzae in Korea.

• 한국균학회소식:학술대회논문집
• /
• 한국균학회 2016년도 춘계학술대회 및 임시총회
• /
• pp.25-25
• /
• 2016

Biological control has many advantages as a disease control method, particularly when compared with pesticides. One of the most important benefits is that biological control is an environmental friendly method and does not introduce pollutants into the environment. Another great advantage of this method is its selectivity. Selectivity is the important factor regarding the balance of agricultural ecosystems because a great damage to non target species can lead to the restriction of natural enemies' populations. The objective of this research was to evaluate the effects of several different bacterial isolates on the efficacy of biological control of soil borne diseases. White rot caused by Sclerotium cepivorum was reported to be severe disease of garlic and chive. The antifungal bacteria Burkholderia pyrrocinia CAB08106-4 was tested in field bioassays for its ability to suppress white rot disease. In field tests, B. pyrrocinia CAB08106-4 isolates suppressed white rot in garlic and chive, with the average control efficacies of 69.6% and 58.9%, respectively. In addition, when a culture filtrate of B. pyrrocinia CAB08106-4 was sprayed onto wounded garlic bulbs after inoculation with a Penicillium hirstum spore suspension in a cold storage room ($-2^{\circ}C$), blue mold disease on garlic bulbs was suppressed, with a control efficacy of 79.2%. These results suggested that B. pyrrocinia CAB08106-4 isolates could be used as effective biological control agents against both soil-borne and post-harvest diseases of Liliaceae. Chinese cabbage clubroot caused by Plasmodiophora brassicae was found to be highly virulent in Chinese cabbage, turnips, and cabbage. In this study, the endophytic bacterium Flavobacterium hercynium EPB-C313, which was isolated from Chinese cabbage tissues, was investigated for its antimicrobial activity by inactivating resting spores and its control effects on clubroot disease using bioassays. The bacterial cells, culture solutions, and culture filtrates of F. hercynium EPB-C313 inactivated the resting spores of P. brassicae, with the control efficacies of 90.4%, 36.8%, and 26.0%, respectively. Complex treatments greatly enhanced the control efficacy by 63.7% in a field of 50% diseased plants by incorporating pellets containing organic matter and F. hercynium EPB-C313 in soil, drenching seedlings with a culture solution of F. hercynium EPB-C313, and drenching soil for 10 days after planting. Soft rot caused by Pectobacterium carotovorum subsp. carotovorum was reported to be severe disease to Chinese cabbage in spring seasons. The antifungal bacterium, Bacillus sp. CAB12243-2 suppresses the soft rot disease on Chinese cabbage with 73.0% control efficacy in greenhouse assay. This isolate will increase the utilization of rhizobacteria species as biocontrol agents against soft rot disease of vegetable crops. Sclerotinia rot caused by Sclerotinia sclerotiorum has been reported on lettuce during winter. An antifungal isolate of Pseudomonas corrugata CAB07024-3 was tested in field bioassays for its ability to suppress scleritinia rot. This antagonistic microorganism showed four-year average effects of 63.1% of the control in the same field. Furthermore, P. corrugata CAB07024-3 has a wide antifungal spectrum against plant pathogens, including Sclerotinia sclerotiorum, Sclerotium cepivorum, Botrytis cinerea, Colletotrichum gloeosporioides, Phytophotra capsici, and Pythium myriotylum.

• Mycobiology
• /
• 제33권3호
• /
• pp.163-165
• /
• 2005

In April 2002 and 2003, soft rot on fruit of eggplant (Solanum melongena) caused by Choanephora cucurbitarum was observed in the experimental fields at Gyeongnam Agricultural Research and Extension Services in Korea. The disease began with water-soaking and dark-green lesions, and then the infected tissues were rapidly rotten. Sporangium was subglobose in shape and sized $40{\sim}130\;{\mu}m$. Monosporous sporangiola were elliptic, fusiform or ovoid, brown in color, and measured as $12{\sim}20\;{\times}\;6{\sim}14\;{\mu}m$. Sporangiospores having three or more appendages were elliptic, fusiform or ovoid in shape, dark brown or brown in color, and sized $14{\sim}20\;{\times}7{\sim}16\;{\mu}m$. The fungus grew well on potato dextrose agar between 15 and $40^{\circ}C$ and its optimum growth temperature was $30^{\circ}C$. Based on morphological characteristics, the causal fungus of the fruit soft rot of eggplant was identified as C. cucurbitarum. This is the first report on the soft rot of S. melongena caused by C. cucurbitarum in Korea.

• The Plant Pathology Journal
• /
• 제40권2호
• /
• pp.151-159
• /
• 2024

Bacterial soft rot caused by Pectobacterium carotovorum subsp. carotovorum (Pcc) is one of the most severe diseases in radish cultivation. To control this plant disease, the most effective method has been known to cultivate resistant cultivars. Previously, we developed an efficient bioassay method for investigating resistance levels with 21 resistant and moderately resistant cultivars of radish against a strain Pcc KACC 10421. In this study, our research expanded to investigate the resistance of radish cultivars against six Pcc strains, KACC 10225, KACC 10421, ATCC 12312, ATCC 15713, LY34, and ECC 301365. To this end, the virulence of the six Pcc strains was determined based on the development of bacterial soft rot in seedlings of four susceptible radish cultivars. The results showed that the Pcc strains exhibited different virulence in the susceptible cultivars. To explore the race differentiation of Pcc strains corresponding to the resistance in radish cultivars, we investigated the occurrence of bacterial soft rot caused by the six Pcc strains on the 21 resistant and moderate resistant cultivars. Our results showed that the average values of the area under the disease progress curve were positively correlated with the virulence of the strains and the number of resistant cultivars decreased as the virulence of Pcc strains increased. Taken together, our results suggest that the resistance to Pcc of the radish cultivars commercialized in Korea is more likely affected by the virulence of Pcc strains rather than by race differentiation of Pcc.

• The Plant Pathology Journal
• /
• 제23권4호
• /
• pp.314-317
• /
• 2007

A soft stem rot disease was observed on Chamaecereus silvestrii (Korean name: Sanchui), a scion of graft-cactus, in major growing areas of Suwon (National Horticulture Research Institute), Anseong, Eumseong, Cheonan, Daegu, and Goyang, Korea during 2000 and 2001. Typical symptoms were soft rots characterized by moist and watery decay of the whole cactus stem, which initiated as small water-soaked lesions and enlarged rapidly to the entire stem. The causal organism isolated from the infected stems was identified as Pectobacterium carotovorum subsp. carotovorum (Erwinia carotovora subsp. carotovora) based on its physiological and biochemical characteristics and confirmed by the cellular fatty acid composition and Biolog analyses. Artificial inoculation of the bacterium produced the same soft rot symptoms on the cactus stems, from which the same bacterium was isolated and identified. This is the first report of the P. carotovorum subsp. carotovorum in the graft-cactus C. silvestrii in Korea.

• 식물병연구
• /
• 제10권4호
• /
• pp.260-267
• /
• 2004

2001년부터 2003년에 걸쳐 수확 후 과일가게에서 판매되는 참외의 썩음증상으로부터 Fusarium spp.를 분리하였다. 병든 과실들은 균사로 덮여 있었고 결국 물러 썩었다. 병의 시작은 주로 과실이 달렸던 부위, 꽃이 달렸던 부위 그리고 열매 표면에 병이 시작되었다. 병이 진전됨에 따라 물러 썩는 열매의 표면에는 흰색에서 분홍빛의 균사로 덮혔다. 이들 병든 과실로부터 분리된 Fusarium spp.를 기존에 보고된 균학적 내용과 비교하여 동정한 결과 Fusarium equiseti, F. graminearum, F. monliforme, F. proliferatum, F. sambucinum, F. semitectum으로 동정되었다. 이들 균의 병원성을 조사하기 위해 건전한 참외에 인위적으로 만든 상처와 무상처에 접종한 결과 접종 이틀후, 상처 접종 부위에 기중균사가 형성되었고, 병이 진전됨에 따라 물러 썩었다. 비록 참외에서 Fusarium spp.가 야기하는 열매썩음병은 국내에서 이미 보고된 바가 있으나, 이와 관련된 종에 대해서는 보고된 적이 없다. 따라서, 이 연구를 통해 Fusarium spp.에 의한 수확 후 참외의 열매썩음병을 국내에서 처음으로 보고하는 바이다.

• Mycobiology
• /
• 제39권2호
• /
• pp.140-142
• /
• 2011

Soft rot in apple caused by Rhizopus oryzae was found for the first time in Korea. A detailed description of the specimen is given along with its internal transcribed spacer rDNA sequence. The fungus was identified as Rhizopus oryzae based on the mycological characteristics, molecular data, and pathogenicity testing.

• 식물병연구
• /
• 제29권1호
• /
• pp.72-78
• /
• 2023

In September 2021, gray-to-brown discoloration and expanding water-soaked lesions were observed on the outer and inner layers and the core of kimchi cabbage (Brassica rapa subsp. pekinensis) in fields located in Samcheok, Gangwondo, Korea. A bacterial strain designated as KNUB-02-21 was isolated from infected cabbage samples. Phylogenetic analysis based on the sequences of the 16S rRNA region and the dnaX, leuS, and recA genes confirmed that the strain was affiliated with Pectobacterium versatile. Additionally, the biochemical and morphological profiles of the isolate were similar to those of P. versatile. Based on these results, the isolate was identified as a novel strain of P. versatile. Healthy kimchi cabbage slices developed soft rot upon inoculation with P. versatile KNUB-02-21 and exhibited symptoms similar to those observed in the diseased plants in fields. The re-isolated strains were similar to those of P. versatile. Prior to our study, P. versatile as the causative pathogen of kimchi cabbage soft rot had not been reported in Korea.

• 농약과학회지
• /
• 제13권4호
• /
• pp.275-282
• /
• 2009

선발된 PGPR 균주인 Bacillus subtilis C4와 Bacillus cereus D8 균주의 유채에 대한 생육촉진 및 무름병균인 Erwinia carotovora와 균핵병균인 Sclerotinia sclerotiorum에 대한 방제효과를 검정하기 위하여 실내검정과 온실검정을 실시하였다. 실내검정 결과, C4와 D8균주처리에 의하여 유채의 생육이 40.3%~74% 증가하였으며 무름병이 대조구에 비하여 80% 감소하였다. 실내검정에서 C4와 D8균주를 종자에 처리하였을 때 뿌리가 크게 신장되었다. 주요 식물병원균 Sclerotinia sclerotiorum, Rhizoctonia solani, Botrytis cinerea, Fusarium oxysporum, Phytophthora capsici, Colletotrichum acutatum에 대하여 항균활성시험을 수행한 결과 두 균주 중 C4균주는 모든 병원성 곰팡이에 대하여 항균활성을 나타내었다. 온실검정에서 C4와D8균주처리는 대조구에 비하여 유채의 초장, 엽폭 및 엽장을 19.5%~24.9%, 11.3%~15.3%, 14.1%~20.7% 각각 증가시켰으며 균핵병균인 Sclerotinia sclerotiorum에 대한 억제효과가 우수하였다. 이와 같은 결과를 볼 때 C4, D8 균주 처리는 유채의 생육을 촉진시키며 유채에 저항성을 유도하므로 친환경생물방제에 적용할 수 있을 것으로 생각된다.

• The Plant Pathology Journal
• /
• 제18권1호
• /
• pp.54-55
• /
• 2002

Soaked black rot symptom was observed on the stem of Angelica acutiloba from July to August 2000 at Kumsan, Chungnam in Korea. This disease usually occurred under humid and high temperature conditions. The lesions on the stem appeared as soft rot with brown elliptical spots, which developed into large black spots at a later stage. When the bacterial isolates from the diseased plants were inoculated onto healthy plants by artificial needle prick method, symptoms similar to that observed in the fields developed. According to the cultural characteristics and pathogenicity of the isolates on the host plant the causal bacterium was identified as Xanthomonas campestris. This study proposed that the disease be named "bacterial black stem rot of A. acutiloba"loba".