Stem Rot of Hosta longipes Caused by Sclerotium rolfsii in Korea

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.

Sclerotium rolfsii에 의한 비비추 흰비단병

2004과 2005년 7월 경상남도 진주시 칠암동 남강변에 재배중인 비비추에서 S. rolfsii에 의한 흰비단병이 발생되었다. 병징은 잎자루, 줄기, 지제부위가 수침상으로 물러지고 부패하면서 암갈색으로 되고 시들어 말라 죽는다. 병반부와 지제부위의 토양 표면에 흰색의 곰팡이가 솜털처럼 생기고 갈색의 둥근 균핵을 많이 형성되었다. 감자한천 배지에서 갈색의 둥근 균핵을 많이 형성하였으며 크기는 $1\~3$mm였다. 균사의 폭은 $4\~8{\mu}m$이며, 균사생육 적온은 $30^{\circ}C$였다. 균사특유의 clamp connection이 관찰되었다. 비비추에서 발생한 병징과 균학적 특징 및 병원성을 검정한 결과, 이 병을 Sclerotium rolfsii Saccardo에 의한 비비추 흰비단병으로 명명하고자 한다.