• The Korean Journal of Mycology
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• v.50 no.3
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• pp.235-241
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• 2022

Anthracnose crown rot (ACR) has been observed in greenhouses during the nursery and harvest seasons in Gangwon Province, Korea. Infected plants showed black leaf spot, dark sunken pink conidial masses on petioles, wilting, and eventually death. Five isolates were obtained from the lesions of strawberry plants and were identified as a Colletotrichum gloeosporioides species complex based on their cultural and morphological characteristics. Multilocus sequence analysis of actin, calmodulin, chitin synthase, glyceraldehyde-3-phophate dehydrogenase genes, and internal transcribed spacer rDNA regions showed that the isolates formed a monophyletic group with the type strain of C. siamense. Pathogenicity tests were performed on the isolate, and Koch's postulates were performed to verify the relationship between Colletotrichum sp. and the strawberry plant variety Seolhyang. The isolate was pathogenic to strawberry plants, which exhibited typical ACR symptoms. Based on morphological characteristics, pathogenicity, and DNA sequence analyses, the fungus isolated in Korea was identified as C. siamense. This is first time C. siamense has been confirmed in ever-bearing strawberry varieties in Korea.

• Korean Journal Plant Pathology
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• v.14 no.6
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• pp.654-660
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• 1998

Colletotrichum gloeosporioides and Glomerella cingulata are the most important pathogens causing anthracnose which may reduce the stand rate and yield on wide kinds of plants including strawberry. Average occurrence rate of anthracnose is 36.9% on major strawberry cropping areas in Korea. We newly found that C. gloeosporioides which does not forming a sexual stage, infects strawberry and differs in some characteristics concerning virulence, cultural and morphological properties to G. cingulata which has a sexual stage. C. gloeosporioides was mainly isolated from the crown with 35.2% rate, while G. cingulata was largely isolated from petiole, runner with 40.9% rate in infected strawberry plants. These two pathogens showed significant differences in cultural characteristics such as perfect stage formation, temperature response as well as benomyl resistance. It was demonstrated that C. gloeosporioides has significantly stronger pathogenicity than G. cingulata in pathogenicity test carried on strawberry plants to various strawberry cultivars. Akihime, Akaneko and Nyoho forcing cultured strawberry cultivars, considered to be susceptible, while semiforcing cultured cultivars, such as Suhong and Holowase, were shown resistant to both pathogens. In non-wound inoculation, C. gloeosporioides was shown pathogenicity on the apple fruit, but G. cingulata could not infect it.

• Mycobiology
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• v.44 no.4
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• pp.319-324
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• 2016

Dieback in strawberry (Seolhyang cultivar) was first observed during the nursery season (June to September) in the Nonsan area of Korea in the years 2012 and 2013. Initial disease symptoms included dieback on runners, as well as black rot on roots, followed by wilting and eventually blackened, necrotic discoloration in the crowns of daughter plants. A fungus isolated from the diseased roots, runners, and crowns is close to Lasiodiplodia theobromae based on morphological characteristics. Analysis of a combined dataset assembled from sequences of the internal transcribed spacer and translation elongation factor 1- alpha genes grouped nine fungal isolates with the type strain of L. theobromae. The isolates showed strong pathogenicity on strawberry cultivars Kumhyang, Seolhyang, and Akihimae, fulfilling Koch's postulates. Based on these results, the pathogen responsible for dieback on strawberry plants in Korea was identified as L. theobromae.

• Korean Journal of Organic Agriculture
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• v.13 no.2
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• pp.161-173
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• 2005

This study was carried out to clarify the effects of antifungal bacterial strains isolated from the greenhouse soil grown strawberry plants on the growth inhibition of plant pathogen, gray mold (Botrytis cinerea) infected in strawberry plants in Damyang and Jangheung districts. Antagonistic bacterial strains were isolated and investigated into the antagonistic activity against gray mold. Screened ten bacterial strains which strongly inhibited Botrytis cinerea were isolated from the greenhouse grown strawberry plants, and the best antifungal microorganism designated as SB 143 was finally selected. Antifungal bacterial strain SB 143 was identified to be the genus Bacillus sp. based on the morphological and biochemical characterization. Bacillus sp. SB 143 showed 59.4% of antifungal activity against Botrytis cinerea. By the bacterialization of culture broth and heated filtrates of culture broth, Bacillus sp. SB 143 showed 93.1% and 32.1% of antagonistic activity against Botrytis cinerea.

• The Korean Journal of Mycology
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• v.47 no.4
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• pp.427-435
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• 2019

The occurrence of the crown and root rot on strawberry (Fragaria×ananassa Duch.) has been reported in greenhouses in Sancheong and Hamyang, Gyeongnam province, Korea in June, 2019. The infected plants showed browning rot of the inner crown and root, causing delayed development, lack of growth, and poor rooting. The browning rot of the inner crown and root can sometimes lead to wilting and collapsing of plants. Fungi were isolated from the symptomatic root and crown. Based on the results of morphological and phylogenetic analyses, the causal agent of the disease was identified to be Neopestalotiopsis clavispora. The fungal isolates were then used for inoculation into strawberry plants to determine the causal agent of the crown and root rot as per Koch's postulates. The inoculated strawberry plants showed the same symptoms as the originally infected plants, and the fungal pathogen re-isolated from the lesions showed the same morphological characteristics as the original pathogen. This is the first report on the occurrence of crown and root rot on strawberry (Fragaria×ananassa Duch.) caused by N. clavispora in Korea.

• Journal of Microbiology and Biotechnology
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• v.30 no.5
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• pp.708-716
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• 2020

The purpose of this study was to identify strawberry wilt pathogens and evaluate the efficacy of Chlorella fusca CHK0059 for improving plant growth and suppressing Fusarium wilt. We identified 10 isolates of wilt pathogens of non-pesticide Seolhyang strawberry plant, including Fusarium oxysporum f. sp. fragariae, using morphological and molecular analysis. On the 15^th day after 0.4% CHK0059 treatment, the plant height of the untreated control strawberry plants was significantly greater than that of the CHK0059-treated strawberry plants. After 85 days, both treatments showed a similar tendency regarding the height of the strawberry plants. However, the thickness of strawberry leaves treated with the CHK0059 was found to be 1 mm thicker than that of the untreated control. The flowering percentage of the CHK0059 plants was also 40.2% higher on average than that of the untreated control. The chlorophyll content of strawberry leaves treated with the CHK0059 was also, on average, 6.63% higher than that of the untreated control. After 90 days of the CHK0059 treatment, the incidence of Fusarium wilt in the CHK0059-treated plants had reduced by 9.8% on average compared to the untreated control. The population density of F. oxysporum f. sp. fragariae was also reduced by approximately 86.8% in the CHK0059-treated plants by comparison to the untreated control at 70 days after treatment. The results indicate that the microalga C. fusca CHK0059 is an efficient biological agent for improving strawberry plant growth and suppressing Fusarium wilt disease in organic strawberries.

• The Korean Journal of Mycology
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• v.45 no.4
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• pp.377-380
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• 2017

In 2015, a new leaf spot disease was observed on strawberry seedlings in Wanju, Korea. Tanned brown spots appeared on the leaves of the infected plants, and often coalesced to form larger necrotic areas, resulting in the death of foliage. An isolate was obtained in pure culture. On the basis of morphological characteristics and molecular analysis of internal transcribed spacer rDNA sequence, the causal agent was identified as Pilidium concavum. Pathogenicity tests revealed the isolate was pathogenic to the leaves and fruits of strawberry. To the best of our knowledge, this is the first report of P. concavum causing tan-brown leaf spot on strawberry in Korea.

• Mycobiology
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• v.36 no.3
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• pp.143-147
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• 2008

We have detected the slime mold, Diachea leucopodia (GNU06-10) in a strawberry greenhouse located in Sancheong-gun, Gyeongnam. Typical fruiting bodies had developed gregariously on the strawberry leaves, petioles, and plant debris on ground soil habitat, and also surprisingly on plastic pipes and a vinyl covering. Field samples were examined via stereomicroscopy, light microscopy, and SEM for the determination of morphological characteristics. Dark-brown to black spores formed gregariously within the stipitate cylindrical sporangium, and were covered by an iridescent peridium, which may be intact at maturity, or may have disintegrated. The upper portion of the peridium generally breaks up to expose the spores, whereas the lower portion was usually persistent. The results of energy dispersive X-ray spectrometer (EDS) analysis showed that lime was present in the stalk and columella but absent from the spores, capillitium, and peridium. The above characteristics confirm its taxonomic position in the genus Diachea. However, this genus is intermediate in character between the Physarales and Stemonitales of the Myxogastromycetidae. Hence, this genus had been classified as a member of the Stemonitales until the mid-1970's, on the basis of its iridescent peridium and noncalcareous capillitial system, similar to Comatricha of the Stemonitaceae. By way of contrast, emphasis on morphological characteristics, most notably the calcareous stalk and typical columella, places Diachea within the order Physarales. The presence of a phaneroplasmodium during the trophic stage and lime deposition in its sporophores, as was confirmed in this work, supported the inclusion of Diachea in the Physarales, and the noncalcareous capillitial system verified its identification as a member of the Didymiaceae. Further characteristics of the species D. leucopodia include the following: phaneroplasmodium, spore globose 7.5 ${\mu}m$ in diameter, very minutely roughened; sporangia $500{\mu}m\times1mm$, more or less cylindrical, gregarious, stalked 1.2mm; stalk and columella white.

• Journal of Plant Biotechnology
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• v.46 no.2
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• pp.106-113
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• 2019

The objective of this study was to carry out treatment of various plant hormones in order to determine morphological and genetic variation degree of tissue-cultured strawberry. The cultivar used in this experiment was 'Goha' and 'Seolhyang', the plant hormones used for experiment were benzyladenine (BA), N-(2-Chloro-4 pyridyl)-N'-phenylurea (CPPU) and thidiazuron (TDZ), and the concentrations were 0.5, 1.0, 2.0, $4.0mg{\cdot}L^{-1}$ with each hormone. The BA treatment of the proliferation efficiency of tissue-cultured strawberry 'Goha' and 'Seolhyang' was the highest. When processing BA, CPPU and TDZ, morphological variation and genetic variation happened in strawberry 'Goha' and 'Seolhyang', especially, the variations appeared highly in CPPU treatment. The genetic variation in 'Goha' appeared at the concentration more than BA $0.5mg{\cdot}L^{-1}$ as 1.1%, appeared at the concentration of CPPU $0.5mg{\cdot}L^{-1}$ as 15.3%, and at the concentration of TDZ $2.0mg{\cdot}L^{-1}$ as 1.2%. The genetic variation in 'Seolhyang' appeared at the concentration of BA $4.0mg{\cdot}L^{-1}$ as 2.3%, and at the concentration of CPPU $0.5mg{\cdot}L^{-1}$ as 14.3%. Therefore, CPPU should not be treated during strawberry tissue culture, and BA and TDZ should be treated at low concentration.

• Mycobiology
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• v.37 no.2
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• pp.77-81
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• 2009

This study was conducted to identify the Colletotrichum species causing anthracnose disease of strawberry in Balgladesh and to evaluate in vitro activity of commercial fungicides it. Based on morphological and cultural characteristics, all 22 isolates were identified as Colletotrichum gloeosporioides. They developed white or glittery colonies with grey to dark grey reverse colony colors and they produced cylindrical conidia. The efficacy of five commercial fungicides, Bavistin DF, Dithane M-45, Sulcox 50 WP, Corzim 50 WP and Rovral 50 WP, were tested against the fungus. Bavistin inhibited radial growth completely and was followed in efficacy by Dithane M-45. In Bavistin DF treated media, the fungus did not produce conidia. The percent inhibition of radial growth of the fungus was increased with the increasing concentrations of fungicide.