• The Plant Pathology Journal
• /
• v.29 no.4
• /
• pp.440-445
• /
• 2013

Balloon flower (Platycodon grandiflorum) is a kind of mountain herbs whose roots have restorative properties and the cultivating acreage of balloon flower has been steadily increasing in Korea. More frequent rain and high amount of rainfalls as a result of climate changes predisposed balloon flower to the outbreaks of root rot at high-density cultivation area in recent years. Root crowns were usually discolored into brown to blackish brown at first and the infected plants showed slight wilting symptom at early infection stage. Severely infected roots were entirely rotted and whole plants eventually died at late infection stage. The overall disease severities of root rot of balloon flower were quite variable according to the surveyed fields in Jeonnam, Gyeongnam and Jeju Provinces, which ranged from 0.1% to 40%. The root rot occurred more severely at the paddy or clay soils than the sandy soils and their severities were much higher at lowland than upland in the same localty. The disease increased with aging of the balloon flower. The causal fungi were identified as Fusarium solani and F. oxysporum on the basis of their mycological characteristics. The optimum temperature ranges of their mycelial growths was found to be $24^{\circ}C$. The pathogenic characters of F. solani and F. oxysporum treated by artificial wounding inoculation on healthy roots of balloon flower revealed that F. solani was more virulent than F. oxysporum. This study identified the causal agents of root rot of balloon flower as Fusarium solani and F. oxysporum, probably for the first time.

• The Korean Journal of Mycology
• /
• v.28 no.1
• /
• pp.46-48
• /
• 2000

The gray mold disease was severely occurred on safflower grown in experimental farm of Kyongsangnam-do Agricultural Research and Extension Services in 1999. At first, the infected leaves discolored gray or dark from the tip and gradually expanded to downword. The fungus also attacked stem, pod and calyx. The infected area became dark and dried, and frequently gray mold grown on the infected area. The causal organism was isolated and proved its pathogenecity according to Koch's postulate. Conidia of the fungus in mass were hyaline or gray, 1-celled, mostly ellipsoid or ovoid and sized $7.4{\sim}16.8{\times}5.3{\times}10.4\;{\mu}m$. Conidiophores were observed with their wide size of $2.9{\times}15.5\;{\mu}m$. The temperature range for mycelial growth was between $5^{\circ}C\;and\;30^{\circ}C$ with the optimum temperatures of $20^{\circ}C\;and\;25^{\circ}C$. The causal organism was identified as Botrytis cinerea and based on mycological characteristics examined. This is the first report on gray mold of safflower caused by Botrytis cinerea in Korea.

• The Korean Journal of Mycology
• /
• v.31 no.2
• /
• pp.117-119
• /
• 2003

A stem rot of eggplant (Solanum melongena) was found in experimental field of Gyeongsangnam-do Agricultural Research and Extension Services, Korea. The typical symptoms of the disease were stem rot, crown rot, wilt or blight. Upper parts of the infected stems were mostly blighted and white turf of fungal mycelium mats was spread over lesions. Sclerotia were farmed on the stems near soil line. The sclerotia of the fungus eadily were produced in artificial media such as PDA at $30^{\circ}C$. The sclerotia were globoid, $1.0{\sim}3.4mm$ in diameter and brown in color. The optimum temperature for growth of the fungus was about $30^{\circ}C$. The typical clamp connections were found in the hypha formed on PDA, and was $3.8{\sim}10.6{\mu}m$ in size. On the basis of mycological characteristics and pathogenecity test, the fungus was identified as Sclerotium rolfsii. This is the first report of stem rot of eggplant caused by Sclerotium rolfsii in Korea.

• The Korean Journal of Mycology
• /
• v.35 no.1
• /
• pp.54-57
• /
• 2007

Rhizopus soft rot caused by Rhizopus stolonifer occurred on banana (Musa sapientum) in the box at Jinju City Wholesale Market of Agricultural Products at Gyeongnam province in Korea. The infected fruits were rapidly water-soaked, softened, blackened and eventually rotted. They were infected from wounds at harvest time. The colony of the isolate from the infected fruit was white to light brown and formed many sporangiospores. The optimum growth temperature of the fungus on potato dextrose agar was $30^{\circ}C$. Sporangiophores were $12{\sim}26\;{\mu}m$ in width. Sporangia were globose or hemispheric, white at first and changed gradually to black, and $83{\sim}195\;{\mu}m$ in size. Columella were hemispheric, and $72{\sim}125\;{\mu}m$ in size. Sporangiospores were irregular round or oval, brownish-black and $9{\sim}20{\times}7{\sim}8\;{\mu}m$ in size. On the basis of symptom, mycological characteristics and pathogenicity to banana, the causal fungus was identified as Rhizopus stolonifer. This is the first report of Rhizopus soft rot by R. stolonifer on banana in Korea.

• The Korean Journal of Mycology
• /
• v.36 no.2
• /
• pp.199-202
• /
• 2008

Rhizopus soft rot caused by Rhizopus stolonifer occurred on melon (Cucumis melo L.) in the box at Jinju City Wholesale Market of Agricultural Products at Gyeongnam province in Korea. The infected fruits were rapidly water-soaked, softened, black and eventually rotted. The symptoms were infected from wounds at harvest time. The colony were white to light brown, formed much sporangiospores. The optimum temperature of the fungus was $30^{\circ}C$. Sporangia were globose or hemispheric, white at first and gradually to black, and $80{\sim}195\;{\mu}m$ in size. Sporangiophores were $12{\sim}24\;{\mu}m$ in width. Columella were hemispheric, and $70{\sim}90\;{\mu}m$ in size. Sporangiospores were irregular round or oval, brownish-black and $9{\sim}20\;{\times}\;6{\sim}8\;{\mu}m$ in size. On the basis of symptom, mycological characteristics and pathogenicity to melon, the causal fungus was identified as Rhizopus stolonifer (Ehrenb.) Vuill.. This is the first report of Rhizopus soft rot by R. stolonifer on melon in Korea.

• The Korean Journal of Mycology
• /
• v.40 no.2
• /
• pp.124-126
• /
• 2012

Stem rot symptoms of Eupatorium lindleyanum occurred sporadically in the herb exhibition field at Hamyang-gun Gyeongsangnam-do Agricultural Research and Extension Services in Korea. The typical symptom included water-soaking on the main stem, rotting, wilting, and blighting, which eventually leads to death of the plant. The sclerotia, white to brown, globoid with size of 1-3 mm, were formed over lesions and surface soil line. The optimum temperature for mycelial growth and sclerotia formation was $30^{\circ}C$ on PDA. The typical clamp connections were observed in the hyphae of the fungus grown on PDA. Mycological characteristics and pathogenicity to host plants indicated that the infected fungus was Sclerotium rolfsii Saccardo. This is the first report of stem rot on Eupatorium lindleyanum caused by S. rolfsii in Korea.

• Research in Plant Disease
• /
• v.12 no.1
• /
• pp.55-57
• /
• 2006

Stem rot of Houttuynia cordata occurred in the experiment field of Research Institute of Natural Product, Uiseong, Gyeongbuk, Korea in July 2003. The typical symptoms of the disease were water-soaking, stem rot, necrotic tuber. White mycelial mats were spread over lesions and sclerotia were formed on died plant and near soil line. The sclerotia were spherical and irregular, 1-2.5 mm on potato dextrose agar (PDA), white to brown in color, The optimal temperature for hyphal growth was $28{\sim}30^{\circ}C$ and the hyphal diameter was $3{\sim}9{\mu}m$. Clamp connections were observed on PDA. Pathogenicity of the casual organism was provided on H. cordata according to Koch's postulate. The fungus was identified as Sclerotium rolfsii Saccardo on the basis of mycological characteristics and pathogenicity test to host plants. This is the first report on the stem rot of H. cordata caused by S. rolfsii in Korea.

• Research in Plant Disease
• /
• v.12 no.1
• /
• pp.58-61
• /
• 2006

Ggray mold caused by Botrytis cinerea occurred on Balsam pear (Momordica charantia) at Daesan-myon, Changwon city, Gyeongnam province in Korea from 2004 to 2006. The disease symptoms usually started with water-soaking lesions on the fruits tip and stem, and then the infected plants became withered and eventually died. The conidia of the pathogen appeared on the surface of fruit and stem of infected plants. The conidia were one celled and mostly ellipsoid or ovoid in shape and were light gray in color, The conidia were $6{\sim}20X4{\sim}12{\mu}m$ in size and conidiophores were $14{\sim}30{\mu}m$ in length. The sclerotia formed abundantly on potato-dextrose agar 18 days after incubation. The optimum temperature for sclerotial formation was $20^{\circ}C$. Pathogenicity of the causal organism was proved according to Koch,s postulates. The causal organism was identified as Botrytis cinerea Persoon: Fries based on the mycological characteristics. This is the first report on gray mold of M. charantia caused by B. cinerea in Korea.

• Research in Plant Disease
• /
• v.11 no.2
• /
• pp.201-203
• /
• 2005

The stem rot disease was found on Hosta longipes that planted in the flower beds along the Namgang riverside in Jinju city, Korea. The disease occurred first time in July, 2004 and sporadically occurred in 2005. The typical symptom of the disease is water-soaking, dark brown spot on the stem, and getting wilt. The infected plants were mostly died. White mycelial mats were spread over lesions and sclerotia were formed on stems and near soil line. The sclerotia were globoid in shape, $1\~3$ mm in diameter and white to brown in color, The optimum temperature for mycelial growth of the fungus on PDA was $30^{\circ}C$ and the hyphal width was $4\~8{\mu}m$. Clamp connections were observed in the hyphae of the fungus grown on PDA. Pathogenicity of the causal organism was proved on Hosta longipes according to Koch,s postulate. On the basis of mycological characteristics and pathogenicity to host plants, the fungus was identified as Sclerotium rolfsii Saccardo. This is the first report on the stem rot of H. longipes caused by S. rolfsii in Korea.

• Research in Plant Disease
• /
• v.11 no.2
• /
• pp.204-207
• /
• 2005

A Rhizopus soft rot caused by Rhizopus stolonifer occurred on Momordica charantia at Daesan-myon, Chang-won city, Gyeongnam province from 2003 to 2005. The disease usually started from wound on fruit with water-soaking lesions. The lesion rapidly expanded and softened. The fungal mycelia grew vigorously and sporangia, sporangiophores, and stolons were formed on surface of the fruit. Spoyangiophores were $15\~30{\mu}m$ in width. Sporangia were globose or hemispheric and $90\~180{\mu}m$ in size. The color of sporangia was white and cottony at first and turned to brownish black with many spores at maturity. Columella were hemispheric and $80\~150{\mu}m$ in size. Sporangiospores were irregular round or oval, brownish-black streaked and $7\~18{\times}6\~12{\mu}m$ in size. The optimum temperature for mycelial growth of the fungus on PDA was $25^{\circ}C$. On the basis of mycological characteristics and pathogenicity to host plants, the causal fungus was identified as Rhizopus stolonifer (Ehrenberg ex. Fr,) Lind. This is the first report of Rhizopus soft rot on M. charantia caused by R. stolonifer in Korea.