Occurrence of Freesia Basal Rot Caused by Sclerotium sp.

Lee, Sang Yeob; Ryu, Jae Gee; Kim, Yong Ki

Research in Plant Disease 2006;12(2):69-74.
Published online August 30, 2006.

Sclerotium sp.에 의한 프리지아 균핵병 발생

이상엽, 류재기, 김용기

Occurrence of Freesia Basal Rot Caused by Sclerotium sp.

Sang Yeob Lee, Jae Gee Ryu, Yong Ki Kim

Abstract

Basal rot of freesia caused by a Sclerotium sp. occurred at Incheon areas. Incidence of the disease reached up to 45% and averaged 17.0% in the fields. Typical symptoms consisted of sheath dry and leaf blight due to rots on basal leaves. The causal fungus was identified as Sclerotium sp. based on following mycological characteristics. The fungus formed sclerotia on cultural media and plant tissues, but did not produce asexual spores. On cultural medium, aerial mycelia of the fungus changed color from white to clay with cultural age and smelled musty odor. Numerous irregular and elliptical black microsclerotia of the fungus were formed on potato dextrose agar (PDA) after 5 days of incubation at 25oC and sized 115~200 × 95~150 (av. 145~126.5) μm. The fungus grew at 10~32oC and pH 4.0~8.5. However, the optimal temperature and pH for mycelial growth of the fungus were 24oC and 5.5 respectively. The isolate showed present pathogenicity to not only freesia but gladiolus in the pathogenicity test, and the symptoms were similar to those observed in the fields. Basal rot of freesia caused by Sclerotium sp. is firstly reported in Korea.

Key Words: Basal rot, Fresia (Freesia hybrida), Sclerotium sp.