Stem Rot of Euphorbia marginata Caused by Sclerotium rolfsii

Stem rot symptoms of Euphorbia marginata were occurred in the herb exhibition field at Gyeongsangnam-do Agricultural Research and Extension Services in Korea. The typical symptom was started with watersoaking lesion on the stem then gradually rotted, wilted, and blighted, the severely infected plants were eventually died. The sclerotia of the pathogen were globoid in shape, 1~3mm in size and white to brown in color. The optimum temperature for mycelial growth and sclerotia formation on PDA was $30^{\circ}C$. The hyphal width was 4~9 ${\mu}m$, and the typical clamp connection structures were observed in the hyphae of the fungus grown on PDA. On the basis of mycological characteristics and pathogenicity to host plants, this fungus was identified as Sclerotium rolfsii Saccardo. This is the first report of stem rot on E. marginata caused by S. rolfsii in Korea.

Sclerotium rolfsii에 의한 설악초 흰비단병

경상남도농업기술원 화단에서 S. rolfsii에 의한 설악초 흰비단병이 발생되었다. 병징은 줄기가 수침상으로 물러지고 썩으면서 서서히 시들어 말라 죽었다. 병든 줄기와 지제부, 토양 표면에 흰색의 곰팡이가 발생하고 갈색의 작은 둥근균핵을 많이 형성하였다. 균핵의 크기는 1~3mm이며 균사의 폭은 4~9 ${\mu}m$였다. 균사특유의 clamp connection이 관찰되었다. 균사생육과 균핵형성 적온은 $30^{\circ}C$이었다. 설악초에서 발생한 병징과 병원균의 균학적 특징을 조사한 결과, 이 병을 Sclerotium rolfsii Saccardo에 의한 설악초 흰비단병으로 명명하고자 제안한다.