Gymnosporangium species causing cedar-apple rust diseases in Korea

Cedar-apple rust fungi had been collected at 36 sites throughout the country from 1984 to 2001 and deposited at the Herbarium of Korea Forest Research Institute (HKFRI). We conducted the morphological examination on the dried specimens by light and scanning electron microscopy and as results six Gymnosporangium species were identified. Three species, G. asiaticum, G. clavaritforme and G. yamadae, were previously described in Korea, while the other three species, G. cornutum, G. globosum, and G. japonicum were new to Korea. Here we present the detailed morphological descriptions, distribution, host ranges and keys to species in both aecial and telial stages of each species. Some morphological characteristics related with telial formation on trees were newly identified; witches brooms for G. asiaticum, small galls for G. yamadae and telial formations on trunk for G. japonicun Geographically G. asiaticum and G. yamadae distributed widely throughout Korea, while the others were collected only at the limited locations. Eight Juniperus species as telial hosts and fifteen Rosaceous plants as aecial hosts were confirmed to be new in Korea.