• The Plant Pathology Journal
• /
• v.19 no.3
• /
• pp.152-158
• /
• 2003

Stromata of the white root rot fungus, Rosellinia necatrix, were produced on diseased roots although they were reported to develop rarely in nature. Forty-two (42) out of 47 samples produced synnemata while 23 developed stromata. Forty-seven (47) isolates obtained from diseased root samples were divided into 24 mycelium compatibility groups (MCGs). Sixteen (16) out of 24 MCGs produced stromata. Single ascospore isolates from 10 stroma samples produced dsRNA-containing isolates from diseased tissue beneath stromata. The frequency of synnema production on axenic culture varied among isolates with different origin. The dsRNA was not transmitted vertically to the ascospore offspring despite the infection of various dsRNA in the parental isolates. The dsRNA was absent in 35 ascospore isolates in two stroma samples that originated from the isolates, in which dsRNA was not eliminated by hyphal tip isolation. Consequently, sexual reproduction in the white root rot fungus was suggested to produce propagules as a new infection source and to have the function to eliminate infectious factors such as mycoviruses.

• The Plant Pathology Journal
• /
• v.31 no.2
• /
• pp.115-122
• /
• 2015

Anthracnose, caused by Colletotrichum gloeosporioides (C. gloeosporioides; Teleomorph: Glomerella cingulata), is the most destructive disease that affects sweet persimmon production worldwide. However, the biology, ecology, and genetic variations of C. gloeosporioides remain largely unknown. Therefore, in this study, the development of fungicide resistance and genetic diversity among an anthracnose pathogen population with different geographical origins and the exposure of this population to different cultivation strategies were investigated. A total of 150 pathogen isolates were tested in fungicide sensitivity assays. Five of the tested fungicides suppressed mycelial pathogen growth effectively. However, there were significant differences in the sensitivities exhibited by the pathogen isolates examined. Interestingly, the isolates obtained from practical management orchards versus organic cultivation orchards showed no differences in sensitivity to the same fungicide. PCR-restriction fragment length polymorphism (RFLP) analyses were performed to detect internal transcribed spacer regions and the ${\beta}$-tubulin and glutamine synthetase genes of the pathogens examined. Both the glutamine synthetase and ${\beta}$-tubulin genes contained a complex set of polymorphisms. Based on these results, the pathogens isolated from organic cultivation orchards were found to have more diversity than the isolates obtained from the practical management orchards.

• The Plant Pathology Journal
• /
• v.17 no.2
• /
• pp.101-105
• /
• 2001

A disease survey on the carnation (Dianthus caryophyllus L.) wilt was conducted during the high temperature period (June through August) and the low temperature period (February through May) in 58 greenhouses of its major cultivation areas, including Pusan, Kimhae, and Changwon in Korea from 1998 to 1999. The disease incidence was averaged 5.4% and 11.9% in the low and high temperature periods, respectively. Severe damage was found in summer with high incidences of around 50% in some greenhouses. Close examination of the symptoms and isolation of the causal agent revealed that there was a new disease different from Fusarium wilt caused by Fusarium oxysporum f. sp. dianthi, which was determined as the stub dieback caused by F. was cetermined as the stub dieback caused by F. graminearum (teleomorph : Gibberella zeae). The stub dieback symptoms involved brown rot of stem that started usually from the portion of cutting without discoloration of inner vascular tissues. Seven out of 38 isolates from the wilted plants were identified as F. graminearum, while the others as F. oxysporum f. sp. dianthi. Mycological characteristics of the stub dieback pathogen including colony color, absence of microconidia, and the shape of macroconidia, were consistent with F. graminearum previously described. This is the first report of the carnation stub dieback in Korea.

• The Plant Pathology Journal
• /
• v.38 no.2
• /
• pp.78-89
• /
• 2022

Phaeosphaeria species are pathogenic on wheat, barley and a wide range of wild grasses. To analyze mating type loci of the Phaeosphaeria species and investigate mating type distribution in Iran, we sequenced mating type loci of 273 Phaeosphaeria isolates including 67 isolates obtained from symptomatic leaves and ears of wheat, barley, and wild grasses from two wheat growing region in Iran as well as 206 isolates from our collection from other regions in Iran which were isolated in our previous studies. Mating type genes phylogeny was successfully used to determine the species identity and relationships among isolates within the Phaeosphaeria spp. complex. In this study, we reported seven new host records for Phaeosphaeria species and the Phaeosphaeria avenaria f. sp. tritici 3 group was first reported from Iran in this study. Mating type distribution among Phaeosphaeria species was determined. Both mating types were present in all sampling regions from Iran. We observed skewed distribution of mating types in one region (Kohgiluyeh va Boyer-Ahmad) and equal distribution in the other region (Bushehr). However, when considering our entire dataset of 273 Iranian Phaeosphaeria isolates, the ratio of mating types was not deviated significantly from 1:1 suggesting possibilities for isolates of opposite mating type to interact and reproduce sexually, although the sexual cycle may infrequently occur in some regions especially when the climatic conditions are unfavorable for teleomorph development.

• Research in Plant Disease
• /
• v.28 no.4
• /
• pp.248-251
• /
• 2022

In October 2022, common Asian cowpea (Vigna nakashimae) powdery mildew disease was investigated at Yesan-gun, Chungcheongnam-do, Korea (36°40'12.7"N,126°51'36.4"E). The disease mainly occurred on the front of the leaves, and weak powdery mildew disease occurred on the back side of leaf. The chasmothecia was identified on the back side of the leaf. Analysis of the internal transcribed spacer rDNA sequence and 28S large subunit sequence, along with the morphological characteristics of the anamorph and teleomorph of the causal fungus identified as Podosphaera xanthii. This is the first time in Korea to report common Asian cowpea (Vigna nakashimae) powdery mildew disease caused by Podospaera xanthii.

• Proceedings of the Korean Society of Plant Pathology Conference
• /
• 2003.10a
• /
• pp.125.2-125
• /
• 2003

Since 2000, severe rots on aerial and underground parts of paprika( Capsicum annum L.) has occurred in most cultivation glasshouses throughout the country. Totally 169 isolates of a fungus were consistently isolated from the diseased plant tissues of fruits, stems, branches, and roots collected from 19 farms in six provinces. Anamorph stage of the fungus was identified as Fusarium solani based on morphological characteristics. However, the fungus readily produced sexual structure of perithecia on infected plant tissues and on agar medium. Since the fungus formed abundant perithecia by single isolate, it was considered as a homothallic strain of Nectria hematococn, the teleomorph of F. solani. Irregularly globose perithecia with orange to red color formed sparsely to gregariously on dead tissues of fruits and basal stems at the 3ate infection stage, which is a diagnostic sign for the disease. Abundancy of perithecium varied among isolates and they sized 125-220$\mu\textrm{m}$ in diam. Asci enveloping eight ascospores were cylindrical and measured 60-80x8-12$\mu\textrm{m}$. Ellipsoid to obovate ascospores are two-celled and measured 11-l8${\times}$4-7$\mu\textrm{m}$. Ascospores are hyaline, slightly constricted at the central septum, and revealed longitudinal striations that is a typical trait of the species. This fungus that has never been reported in Korea previously became a threat to paprika cultivation because of its strong pathogenicity and nationwide distribution.

• The Plant Pathology Journal
• /
• v.28 no.4
• /
• pp.357-363
• /
• 2012

Several species belonging to the Gibberella fujikuroi species (Gf ) complex are commonly associated with rice and corn, not only causing serious diseases, but also producing fumonisins, a group of mycotoxins harmful to animals and humans. To characterize the population structure of the putative fumonisin-producing Gf complex in Korea, we obtained 276 candidate isolates from rice and corn harvested in 2009 and 2010 by diagnostic polymerase chain reaction with several specific primer sets. Phylogenetic trees were constructed using multilocus sequences (combined RPB2 and EF1A, totaling 1.6 kb) from these isolates. Among the 135 isolates from rice, F. fujikuroi (teleomorph: G. fujikuroi; 59.3%) and F. proliferatum (G. intermedia; 13.3%) were predominant, followed by F. concentricum (5.9%). Additionally, twenty-five (18.5%) rice isolates belonged in a distinct subclade of F. commune, a non-member of the Gf complex. In contrast, F. verticillioides was the most predominant species (38.3%) among the 141 corn isolates, and followed by F. fujikuroi (27.7%), F. proliferatum (14.9%), F. subglutinans (7.1%), and F. concentricum (2.8%). A single mating type (MAT1-1) was found predominantly among the Gf complex isolates examined. Possible distinct subclades were detected within the populations of F. fujikuroi and F. proliferatum; however, this needs further confirmation. This is the first reported population-level characterization of putative fumonisin-producing Gf complex associated with rice and corn in Korea.

• The Plant Pathology Journal
• /
• v.28 no.2
• /
• pp.164-171
• /
• 2012

Rice blast disease caused by Magnaporthe grisea (Hebert) Barr [teleomorph] is one of the most devastating diseases in rice plantation areas. Silicon is considered as a useful element for a large variety of plants. Rice variety MR219 was grown in the glasshouse to investigate the function of silicon in conferring resistance against blast. Silica gel was applied to soil while sodium silicate was used as foliar spray at the rates of 0, 60, 120, 180 g/5 kg soil and 0, 1, 2, 3 ml/l respectively. The treatments were arranged in a completely randomized design. Disease severity and silicon content of leaves were compared between the non-amended controls and rice plants receiving the different rates and sources of silicon. Silicon at all rates of application significantly (${\alpha}$ = 0.05) reduced the severity of disease with highest reduction (75%) recorded in treatments receiving 120 g of silica gel. SEM/EDX observations demonstrated a significant difference in weight concentration of silicon in silica cells on the leaf epidermis between silicon treated (25.79%) and non treated plants (7.87%) indicating that Si-fertilization resulted in higher deposition of Si in silica cells in comparison with non-treated plants. Application of silicon also led to a significant increase in Si contents of leaves. Contrast procedures indicated higher efficiency of silica gel in comparison to sodium silicate in almost all parameters assessed. The results suggest that mitigated levels of disease were associated with silicification and fortification of leaf epidermal cells through silicon fertilization.

• The Korean Journal of Mycology
• /
• v.46 no.1
• /
• pp.69-74
• /
• 2018

The Rhododendron powdery mildew fungus Erysiphe izuensis has been recorded throughout Asia, including China, Japan, Korea, and Russia. In Korea, E. izuensis has been identified based on morphological characteristics of the anamorph found on introduced Rhododendron spp. We here describe the first identification of E. izuensis collected from Rhododendron yedoense f. poukhanense in Korea. Morphological characteristics of the teleomorph as well as internal transcribed spacer sequences of the species are provided. Moreover, we describe the characteristics of the primary conidia and conidial surface pattern of E. izuensis for the first time.

• The Plant Pathology Journal
• /
• v.21 no.4
• /
• pp.317-321
• /
• 2005

Since 2000 severe rots on aerial and underground parts of paprika (Capsicum annum L.) has occurred in most surveyed glasshouses throughout the country. A total of 56 isolates of a fungus were consistently isolated from various plant parts such as fruit, stem, branch, and root collected from 16 farms in five provinces. Anamorph stage of the fungus was identified as Fusarium solani based on its morphological characteristics. However, the fungus readily produced a sexual structure of perithecia on infected plant tissues and on agar media. Since the fungus formed abundant perithecium by a single isolate, it was considered as a homothallic strain of Nectria haematococca, the teleomorph of F. solani. Irregularly globose perithecia with orange to red color formed sparsely to gregariously on dead tissues of fruits and basal stems at the late infection stage, which is a diagnostic sign for the disease. Perithecia ranged from 125 to 220 ${\mu}m$ in diameter varied among isolates. Asci enveloping eight ascospores were cylindrical and measured 60-80x8-12 ${\mu}m$. Ellipsoid to obovate ascospores are two-celled and measured 11-18x4-7 ${\mu}m$. Ascospores were hyaline, slightly constricted at the central septum, and revealed longitudinal striations that is characteristic of the species. This fungus that has never been reported in Korea has previously become a threat to paprika cultivation because of its strong pathogenicity and nationwide distribution.