• The Plant Pathology Journal
• /
• v.19 no.6
• /
• pp.274-279
• /
• 2003

Two Gymnosporangium species, G. japonicum and G. cornutum, causing cedar-apple rust, were newly identified in Korea, and a new aecial host for each fungus was found by artificial inoculation. Detailed descriptions of the species were made based on macroscopic features (symptoms and signs) and light and scanning electron microscopic observations of spores and peridial cells. G. japonicum from Juniperus chinensis var. horizontalis had Photinia villosa as its new aecial host G. cornutum from J. rigida showed its aecial stage on Sorbus alnifolia.

• Proceedings of the Korean Society of Plant Pathology Conference
• /
• 2003.10a
• /
• pp.133.2-134
• /
• 2003

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.

• International Journal of Computer Science & Network Security
• /
• v.21 no.7
• /
• pp.324-330
• /
• 2021

Agriculture is one of the essential needs of human life on planet Earth. It is the source of food and earnings for many individuals around the world. The economy of many countries is associated with the agriculture sector. Lots of diseases exist that attack various fruits and crops. Apple Tree Leaves also suffer different types of pathological conditions that affect their production. These pathological conditions include apple scab, cedar apple rust, or multiple diseases, etc. In this paper, an automatic detection framework based on deep learning is investigated for apple leaves disease classification. Different pre-trained models, VGG16, ResNetV2, InceptionV3, and MobileNetV2, are considered for transfer learning. A combination of parameters like learning rate, batch size, and optimizer is analyzed, and the best combination of ResNetV2 with Adam optimizer provided the best classification accuracy of 94%.

• Proceedings of the Korean Society of Plant Pathology Conference
• /
• 2003.10a
• /
• pp.134.1-134
• /
• 2003

Aecial host ranges of four Gymnosporangium species causing cedar-apple rust diseases, G. asiaticum, G. cornutum, 5. japonicum and G. yamadae, were investigated through artificial inoculation. Thirteen species of nine genera among Rosaceous plants, which have been reported as social hosts in Korea, were inoculated with fresh teliospores spores in early days of May of 2000 and of 2001, respectively. In the results, we re-confirmed that there was highly specific relationship between the rust species and aecial hosts and report new aecial hosts of four Gymnosporangium species. Teliospores of G. cornutum collected from Juniperus rigida successively produced spermogonia and aecia only on Sorbus alntifolia, the first report on host alteration of G. cornutum in Korea. Positive responses by teliospores of G. japonicum from J. chinenis of Suwon and from J. chinenis var. horizontalis of Jeju island were obtained only on P. villosa. Crataegus pinnatifida was confirmed as a new aecial host of G. viatium. Until this time, G. ymadae was believed to have Malus as the aecial host. However, teliospores of G. yamadae collected from J. chinensis var. kaizuka successively formed spermogonia and aecia on the leaves of Chaenomeles lagenaria, C. sinensis, Pyrus pyrtifolia var, culta, P. ussuriensis, Malus pumila and M. sileboldii. The date for maturation of spermogonia and aecia, and symptom development varied according to the rust fungi and aecial host plants, respectively.

• Research in Plant Disease
• /
• v.24 no.4
• /
• pp.249-256
• /
• 2018

Disease occurrence in apple cultivars on 13-30 apple orchards from April to October 1992-2010 was investigated at 30 days intervals in Gyeongbuk, Gyeongnam and Jeonbuk provinces of Korea. Apple cultivar 'Fuji' was found most susceptible and is being damaged by cedar apple rust, scab, gray mold, Alternaria blotch and Marssonia blotch as major leaf diseases that were observed. The percentage of occurrence of these leaf diseases varies from every year. This variation is based on different rainfall and temperature conditions, cultivation, root stock and changed system of fungicide spray during the particular year and season.

• The Plant Pathology Journal
• /
• v.21 no.4
• /
• pp.310-316
• /
• 2005

The objectives of this study were to identify the aecial host ranges of four Korean Gymnosporangium species, G. asiaticum, G. cornutum, Gjaponicum and Gyamadae, and to verify the morphological characteristics of telia as diagnostic keys to the species. Thirteen Korean Rosaceous woody species were artificially inoculated with teliospores obtained from Juniperus species. There was high specificity between telial and aecial hosts and the fungal species, providing the first experimental proof on host alternation of these rust fungi in Korea. Telia on the witches' broom and on the small galls were identified as new telial characteristics in G asiaticum and in G. yamadae, respectively. Aecial hosts of G. asiaticum and G. yamadae showed varying responses in their susceptibility and in the days required for formation and duration of spermogonia and aecia after inoculation. Four telial host species in Juniperus were confirmed for the first time in Korea, which include J. chinensis var. kaizuka, J. chinensis var. horizontalis and J. chinensis var. globosa for G. asiaticum; and J. chinensis var. kaizuka for G. yamadae.