First Report of Leaf Spot Caused by a Provisionally Novel Species of Pseudocercospora on Ligustrum japonicum in South Korea

In South Korea, the culture, production, and consumption of blueberry (Vaccinium corymbosum) have increased rapidly over the past 10 years. In June and July 2012, blueberry plants with leaf spots (~10% of disease incidence) were sampled from a blueberry orchard in Jinju, South Korea. Leaf symptoms included small (1 to 5 mm in diameter) brown spots that were circular to irregular in shape. The spots expanded and fused into irregularly shaped, large lesions with distinct dark, brownish-red borders. The leaves with severe infection dropped early. A fungus was recovered consistently from sections of surface-disinfested (1% NaOCl) symptomatic leaf tissue after transfer onto water agar and sub-culture on PDA at 25°C. Fungal colonies were dark olive and produced loose, aerial hyphae on the culture surfaces. Conidia, which had 3 to 6 transverse septa, 1 to 2 longitudinal septa, and sometimes also a few oblique septa, were pale brown to golden brown, ellipsoid to ovoid, obclavate to obpyriform, and 16 to 42 × 7 to 16 μm (n = 50). Conidiophores were pale to mid-brown, solitary or fasciculate, and 28 to 116 × 3 to 5 μm (n = 50). The species was placed in the Alternaria alternata group (1). To confirm the identity of the fungus, the complete internal transcribed spacer (ITS) rDNA region of a representative isolate, AAVC-01, was amplified using ITS1 and ITS4 primers (2). The DNA products were cloned into the pGEM-T Easy vector (Promega, Madison, WI) and the resulting pOR13 plasmid was sequenced using universal primers. The resulting 570-bp sequence was deposited in GenBank (Accession No. KJ636460). Comparison of ITS rDNA sequences with other Alternaria spp. using ClustalX showed ≥99% similarity with the sequences of A. alternata causing blight on Jatropha curcas (JQ660842) from Mexico and Cajannus cajan (JQ074093) from India, citrus black rot (AF404664) from South Africa, and other Alternaria species, including A. tenuissima (WAC13639) (3), A. lini (Y17071), and A. longipes (AF267137). Two base substitutions, C to T at positions 345 and 426, were found in the 570-bp amplicon. Phylogenetic analysis revealed that the present Alternaria sp. infecting blueberry grouped separately from A. tenuissima and A. alternata reported from other hosts. A representative isolate of the pathogen was used to inoculate V. corymbosum Northland leaves for pathogenicity testing. A conidial suspension (2 × 104 conidia/ml) from a single spore culture and 0.025% Tween was spot inoculated onto 30 leaves, ranging from recently emerged to oldest, of 2-year-old V. corymbosum Northland plants. Ten leaves were treated with sterilized distilled water and 0.025% Tween as a control. The plants were kept in a moist chamber with >90% relative humidity at 25°C for 48 h and then moved to a greenhouse. After 15 days, leaf spot symptoms similar to those observed in the field developed on the inoculated leaves, whereas the control plants remained asymptomatic. The causal fungus was re-isolated from the lesions of the inoculated plants to fulfill Koch's postulates. To our knowledge, this is the first report of Alternaria sp. on V. corymbosum in South Korea. References: (1) E. G. Simmons. Page 1797 in: Alternaria: An Identification Manual. CBS Fungal Biodiversity Centre, Utrecht, The Netherlands, 2007. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990. (3) M. P. You et al. Plant Dis. 98:423, 2014.

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First Report of Leaf Spot Caused by Pseudocercospora ligustri on Ligustrum japonicum ‘Howardii’ in China

Plant Disease ◽

10.1094/pdis-05-18-0852-pdn ◽

2019 ◽

Vol 103 (1) ◽

pp. 153-153

Author(s):

S. H. Wang ◽

S. M. Liu

Keyword(s):

Leaf Spot ◽

First Report ◽

Ligustrum Japonicum

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First report of Pseudomonas amygdali causing bacterial leaf spot of Mallotus japonicus in South Korea

Forest Pathology ◽

10.1111/efp.12707 ◽

2021 ◽

Author(s):

Hye Young Yun ◽

Hongsup Kim

Keyword(s):

South Korea ◽

Leaf Spot ◽

Bacterial Leaf Spot ◽

First Report ◽

Mallotus Japonicus ◽

Pseudomonas Amygdali

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First Report of Kiwifruit Brown Leaf Spot Caused by Fusarium tricinctum in South Korea

Journal of Agriculture & Life Science ◽

10.14397/jals.2019.53.3.135 ◽

2019 ◽

Vol 53 (3) ◽

pp. 135-140

Author(s):

Min-jung Kim ◽

◽

Youngho Kwon ◽

Youn-Sig Kwak

Keyword(s):

South Korea ◽

Leaf Spot ◽

First Report ◽

Brown Leaf Spot ◽

Brown Leaf ◽

Fusarium Tricinctum

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First Report of Apricot pseudo-chlorotic leaf spot virus Infecting Peach Trees in South Korea

Research in Plant Disease ◽

10.5423/rpd.2017.23.1.75 ◽

2017 ◽

Vol 23 (1) ◽

pp. 75-81 ◽

Cited By ~ 2

Author(s):

Sangmin Bak ◽

Euncheol Seo ◽

San Yeong Kim ◽

Won Heum Park ◽

Su-Heon Lee

Keyword(s):

South Korea ◽

Leaf Spot ◽

Spot Virus ◽

First Report ◽

Chlorotic Leaf ◽

Peach Trees

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First Report of Pseudomonas cichorii Associated with Leaf Spot on Soybean in South Korea

Plant Disease ◽

10.1094/pdis-08-11-0653 ◽

2012 ◽

Vol 96 (1) ◽

pp. 142-142 ◽

Cited By ~ 10

Author(s):

S.-M. Yu ◽

Y. H. Lee

Keyword(s):

South Korea ◽

16S Rdna ◽

Leaf Spot ◽

Hypersensitive Reaction ◽

Original Strain ◽

Pseudomonas Cichorii ◽

First Report ◽

Oriental Melon ◽

Glycine Max L ◽

Soybean Plants

Unusual symptoms were observed on 5% of the soybean (Glycine max (L.) Merill) plants in commercial fields in South Korea in September 2008 and 2009. The lesions were at first water soaked, then enlarged and turned dark brown or black, often with concentric white rings and sometimes surrounded by a bright yellow halo. Most lesions were roughly circular to irregular. Six bacteria were isolated on tryptic soy agar (TSA) media from plants of soybean cv. Daewon. The isolate JBC1 formed colonies that were whitish to greenish, circular with convex elevation, and unable to grow anaerobically or at 37°C. Cells of the isolate were rod shaped with polar multitrichous flagella. The isolate was positive for the following characteristics: production of fluorescent and diffusible pigment on King's medium B, production of oxidase, ability to rot potato, and utilization of l-arabinose, d-aspartate, citrate, galactose, glucose, meso-inositol, mannitol, and meso-tartrate. However, the isolate was negative in the following tests: formation of yellow colonies on peptone sucrose agar and yeast extract dextrose calcium carbonate agar media, levan formation, production of nondiffusible pigment, urease and arginine dihydrolase, hydrolysis of starch, nitrate reduction, and utilization of d-arabinose, benzoate, geraniol, l-rhamnose, d-sorbitol, sucrose, and trehalose (1). The isolates elicited a clear hypersensitive reaction in tobacco leaves. The carbon source oxidation pattern analyzed by Biolog (Hayward, CA) GN database indicated that the isolate belonged to Pseudomonas cichorii (Swingle 1925) Stapp 1928. DNA was isolated with a commercial genomic DNA extraction kit (Solgent, Daejeon, South Korea) and the 16S rDNA was amplified using universal 27F and 1492R primers. The 1,367-bp amplicon was sequenced (GenBank Accession No. JF951725) and had 100% sequence identity with P. cichorii Accession No. EF101976.1. Phylogenetic analysis based on 1,367 bp of the 16S rDNA sequence also revealed that isolate JBC1 was closely related to P. cichorii. Healthy soybean plants of cv. Jangyeop were spray inoculated with 20 ml of a 108 suspension prepared from a 2-day-old culture grown on TSA. Healthy plants sprayed with just water served as noninoculated checks. Typical disease symptoms that were observed in the field developed on leaves of soybean plants 3 days after spray inoculation, while the check plants remained symptomless. The bacteria reisolated from inoculated plants were confirmed to be identical to the original strain by 16S rDNA analysis and the Biolog test. Inoculation on tomato, watermelon, melon, and oriental melon plants resulted in dark brown or black lesions forming on leaf margins and tips, which is different from those on soybean plants (2,3). With paprika and eggplant, necrotic spots with concentric white rings developed on the leaves of each plant. We propose leaf spot as the name for this disease on soybean. To our knowledge, this is the first report of leaf spot on soybean caused by P. cichorii, which is becoming a more important pathogen in subtropical regions and greenhouses (4). References: (1) B. Cottyn et al. Syst. Appl. Microbiol. 32:211, 2009. (2) A. Obradovic et al. Plant Dis. 86:443, 2002. (3) E. Pauwelyn et al. J. Phytopathol. 159:298, 2011. (4) S. M. Walkil et al. Nigeria J. Appl. Biosci. 38:2540, 2011.

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First Report of Epicoccum tobaicum Associated with Leaf Spot on Flowering Cherry in South Korea

Plant Disease ◽

10.1094/pdis-12-20-2711-pdn ◽

2021 ◽

Author(s):

Viet-Cuong Han ◽

Nan Hee Yu ◽

Hyeokjun Yoon ◽

Youn Kyoung Son ◽

Buoung Hee Lee ◽

...

Keyword(s):

South Korea ◽

Leaf Spot ◽

Disease Incidence ◽

Morphological Characteristics ◽

Leaf Spot Disease ◽

Infected Leaf ◽

First Report ◽

Leaf Spots ◽

Plastic Bag ◽

Flowering Cherry

Flowering cherry (FC, Prunus x yedoensis Matsumura; Somei-yoshino cherry) is an ornamental tree, planted across South Korea and producing stunning flowers in spring. The seasonal blooms are annually celebrated during cherry blossom festivals in many locations across the country. The leaf spot disease is among the most common and important diseases affecting FC trees every year, resulting in premature defoliation and reduced flowering of cherry blossoms in the following year. In May 2018, brown spots (2 to 5 mm), circular to irregular and with dark borders were observed on FC leaves in Hadong, Gyeongsangnamdo, South Korea (35°07'48.9"N, 127°46'53.8"E), with a disease incidence of 55%. Single lesions often coalesced and were sometimes perforated, leaving shot holes. Sampled leaves were surface sterilized with 1% NaOCl for 1 min and 70% ethanol for 30 s, and then rinsed twice with sterile distilled water. About 2-mm-long infected leaf pieces from the margins of lesions were put onto water agar (WA, 1.5% agar) plates and incubated at 25oC for 72 h. Mycelia grown from symptomatic tissue were transferred to PDA plates, and five similar fungal isolates were obtained from hyphal tips. They produced a strong reddish-orange diffusible pigment on PDA after 5 d and exudates after 8 d. Conidia were globular to pear-shaped, dark, verrucose, multicellular, and 14.8 to 23.5 μm in diameter (av. = 18.7 μm, n = 30) for isolate JCK-CSHF10. These morphological characteristics were consistent with the Epicoccum genus. Three loci, ITS, tub2, and rpb2, from three isolates JCK-CSHF8, JCK-CSHF9, and JCK-CSHF10 were amplified using the primer pairs ITS1F/LR5 (Gardes and Bruns 1993; Vilgalys and Hester 1990), Btub2Fd/Btub4Rd (Woudenberg et al. 2009), and RPB2-5F2/RPB2-7cR (Liu et al. 1999; Sung et al. 2007), respectively. The ITS, tub2, and rpb2 sequences of the three isolates were deposited in Genbank (MW368668-MW368670, MW392083-MW392085, and MW392086-MW392088, respectively), showing 99.6 to 100% identity to E. layuense (E33), a later synonym for E. tobaicum (Hou et al. 2020). The phylogenetic tree using concatenated sequences of the three loci placed the three isolates in a cluster of E. tobaicum (CBS 232.59, CGMCC 3.18362, and CBS 384.36; Hou et al. 2020). Taken together, the three isolates were identified as E. tobaicum. The pathogenicity of JCK-CSHF10 was tested on 15 healthy leaves on three FC trees (cv. Somei-yoshino, 1.2 m in height) kept in a greenhouse. Five-mm-diameter plugs from 7-d-old fungal cultures grown on PDA or mycelia-free PDA plugs as controls were placed on the abaxial side of a leaf at three points, previously wounded by a sterile needle (Zlatković et al. 2016). Inoculation sites were covered with moist cotton plugs. Trees were then covered with a clear plastic bag and maintained in high humidity at 25oC in darkness for 24 h, followed by a 12-h photoperiod. Brown spots appeared on inoculated leaves after 7 d, identical to those observed in the field, while control leaves remained symptomless. This experiment was repeated three times. A fungus with the same morphology as JCK-CSHF10 was recovered from lesions, thus confirming Koch’s postulates. E. layuense (syn. E. tobaicum) has been reported as a leaf spot-causing agent on Perilla sp. (Chen et al. 2017) and Camellia sinensis (Chen et al. 2020). To date, there is no report on the occurrence of E. tobaicum from leaf spots on FC. To our knowledge, this is the first report of E. tobaicum causing leaf spot on FC in South Korea.

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TWO NEW SEVERE LEAF SPOT DISEASE ON FOREST TREES OF JALGAON (MAHARASTRA) INDIA

FLORA AND FAUNA ◽

10.33451/florafauna.v23i2pp288-290 ◽

2017 ◽

Vol 23 (2) ◽

Author(s):

S. A. FIRDOUSI

Keyword(s):

Leaf Spot ◽

Fungal Disease ◽

Leaf Spot Disease ◽

Forest Trees ◽

First Report ◽

Spot Disease ◽

Severe Leaf

During the survey of the forest fungal disease, of Jalgaon district, two severe leaf spot diseases on Lannae coromandelica and ( Ougenia dalbergioides (Papilionaceae) were observed in Jalgaon, forest during July to September 2016-17. The casual organism was identified as Stigmina lanneae and Phomopsis sp. respectively1-4,7. These are first report from Jalgaon and Maharashtra state.

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