Seung-Kyu Lee

Identification of Aecial Host Ranges of Four Korean Gymnosporangium Species Based on the Artificial Inoculation with Teliospores Obtained from Various Forms of Telia

The objectives of this study were to identify the aecial host ranges of four Korean Gymnosporangium species,G. asiaticum, G. cornutum, G. japonicum and G. yamadae, 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.

First Report of Gymnosporangium globosum Causing American Hawthorn Rust in Korea

Field surveys and specimen collections of the rust fungal pathogen Gymnosporangium were carried out for 15 years from 1985 through 1999 in various locations of Korea. Macroscopic and microscopic examinations of morphological characteristics of aecia from the collected specimens revealed that Gymnosporangium globosum is the causal agent of American hawthorn rust disease on Crataegus pinnatifida and C. pinnatifida varmajor. The host plants are new for this rust fungus. G. globosum was found only in Gyeonggi and Chungbuk provinces, indicating that its distribution in Korea is limited. This is a first full description on morphological characters of aecia of G. globosum in Korea.

Occurrence of Rhizina Root Rot in a Black Pine (Pinus thunbergii) Forest Located at the Western Coastal Area in Korea and Its Spreading Patterns

At the survey of June, 2002, total 294 dead frees were found in 20 ha of Black pine (Pinus thunbergii) forest located in the western coastal region of Korean peninsula. The dead trees were scattered over the 27 place as groups of about ten trees each. As a result of the field survey on the relationship between the conditions of dead trees and the occurrence of fruiting bodies of Rhizina undulata around the dead and/or dying trees, from June 2002 to August 2004 in the four plots, the occurrence of infected trees was observed as a shape of an irregular concentric circle from the first infected tree and R. undulata was found mainly around the dead tree. Because there was no observation of any other insects and pathogens which would kill trees, the cause of tree death in groups was considered owing to R. undulata. From the analysis of the physical and chemical proper ties of the soil collected from the damaged areas, the pH of soil was between 4.6 and 5.8 and the contents of soil nutrients were very low. Any fire trace was not found at all the 27 damaged places in the area, Taean, Chungcheongnam-Do, which are generally known as an important factor to initiate development of the disease. Therefore, further examination is needed to verify precisely about other environmental factors related with the group dying of the Black pines in this area beside `fire`.

Confirmation of the Presence of Pleochaeta shiraiana Associated with Powdery Mildew of Celtis sinensis in Korea

The presence of Pleochaeta shiraiana associated with powdery mildew of Celtis sinensis in Korea is dubious, mainly due to incomplete records of earlier workers. To confirm the occurrence of the powdery mildew and the identity of the causal fungus, morphological characteristics of the anamorph and teleomorph from nine samples deposited in KUS (Herbarium in Korea University) were examined by light microscopy. Identification of the fungus was supported by comparing four ITS sequences from Korean samples with two Japanese data. This is the first confirmed report of the powdery mildew associated with P. shiraiana in Korea.

Two Newly Identified Gymnosporangium Species, G. japonicum and G. cornutumn, in Korea

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.

Occurrence of Powdery Mildew Caused by Erysiphe abeliicola on Glossy Abelia in Korea

In November 2009, a powdery mildew on glossy abelia (Abelia x grandiflora) was found in Seogwipo, JejuIsland, Korea. Further survey in the southern part of Korea, e.g., Jeju, Busan, and Tongyeong confirmedoccurrence of the disease. White colonies were present on leaves, young stems, and flowers, detracting fromtheir beauty in landscape plantings. Severely infected lesions were discolored to red-purplish. Based on themorphological characteristics and analysis of rDNA, the fungus associated with the symptoms was identifiedas Erysiphe abeliicola U. Braun & S. Takam. This work provides the morphological feature of its anamorphfor the first time, which is characterized by having multi-lobed hyphal appressoria and short foot-cells ofconidiophores. Morphological characteristics of mature chasmothecia were consistent with the previousJapanese record of this species. The sequence of internal transcribed spacer region of ribosomal DNAobtained from a Korean sample showed that this species places in the section Microsphaera of the genusErysiphe in phylogenetic position, corresponding with the classical taxonomy. This is the first report of E.abeliicola and its host plant in Korea. The host plant A. x grandiflora is newly listed in the host range of E.abeliicola.Keywords : Abelia x grandiflora , Anamorph, Erysiphe abeliicola , Glossy Abelia 꽃댕강나무[Abelia x grandiflora (Andre) Rehd.]는 인동과(Caprifoliaceae)에 속하는 반상록성 관목으로 Abeliachinensis와 A. uniflora 사이에서 육성된 종간 잡종이다.우리나라에는 1930년경 일본으로부터 도입되었는데, 도입 초기에는 내한성이 약하여 중부 이북 지역에서는 식재하지 않았지만 최근 들어 전국적으로 식재되고 있다.특히 대기오염에 잘 견디고 맹아력이 강하여 도로변의 생울타리와 건물의 진입로 유도식재로 많이 사용되고 있다(Choi, 2008). 일본에서 기록된 댕강나무류(Abelia spp.)의 병해 중에서 곰팡이에 의한 것은 Cercospora abeliae에 의한 점무늬병, Helicobasidium mompa에 의한 자주날개무늬병,Erysiphe abeliicola에 의한 흰가루병 등 3가지가 있다(ThePhytopathological Society of Japan, 2000). 그러나 우리나라에서는 꽃댕강나무는 물론 댕강나무류에서도 식물병이기록된 바 없다(The Korean Society of Plant Pathology,2009). 한편, 지금까지 전 세계적으로 댕강나무류에서 기록된 흰가루병균은 Erysiphe abeliae R.Y. Zheng & G.Q.Chen, E. abeliicola U. Braun & S. Takam., E. chifengensisT.Z. Liu & U. Braun 등 3종이 있다(Table 1). 이 중, E.abeliae는 중국(쓰촨성)에서만 알려진 토착종이며(Zheng과Chen, 1980), E. chifengensis는 중국(내몽고)에서만 기록되어 있다(Liu와 Braun, 2006). 한편, E. abeliicola는 지금까지 일본에서만 기록되어 있다(Tanda와 Nomura, 1978).저자들은 한국에서 2009년부터 꽃댕강나무에 흰가루병이발생함을 관찰하였으며, 이를Email) hdshin@korea.ac.kr 채집하여 병원균을 동정하

Genotypic Characterization of Cherry Witches` Broom Pathogen Taphrina wiesneri Strains

The ascomycetous fungus Taphrina wiesneri, the pathogen of cherry witches` broom, is highly pathogenic to Prunus yedoensis, the most widely planted cherry trees in Korea as park and roadside trees. A collection of 13 strains of the pathogen in Korea and Japan was characterized by 18S rDNA gene sequence and restriction fragment length polymorphism (RFLP) analysis. In cluster analysis based on 18S rDNA gene sequence the strains were divided into 2 clusters. In RFLP analysis of the rDNA-IGS region using HhaI, the strains were separated into four patterns, B, C, D and G, of which pattern G was new.

Occurrence of Downy Leaf Spot on Juglans regia Caused by Microstroma juglandis in Korea

In June 2011, walnuts (Juglans regia) from orchards in Kimcheon and Muan, in southern Korea, were found to exhibit downy mildew-like symptoms of a foliar disease. Whitish polygonal efflorescence was produced on the abaxial surface of affected leaves and discolored light green blotches on the corresponding adaxial surfaces. In the later stage of disease development, diseased tissues collapsed and became necrotic. Based on morphological and cultural characteristics, the causal fungus was identified as Microstroma juglandis. The sequence of ITS rDNA of the present isolate showed 100% similarity with those of M. juglandis obtained from GenBank databases, thus confirming its identity. Pathogenicity tests were conducted on leaves of walnut seedlings, fulfilling Koch`s postulates. The disease has been previously reported in North America, Europe, Oceania and some western Asia. This is the first report of downy leaf spot on walnuts in East Asia.