First Report of Leaf Blight Caused by Nigrospora sphaerica on Curcuma in China

Curcuma (family Zingiberaceae) is commonly cultivated for the use of rhizomes within traditional Chinese medicines. In October 2009 and 2010, severe leaf blight was observed on Curcuma wenyujin Y.H. Chen & C. Ling (4) in fields located in Ruian, China. The area of cultivation in Ruian encompasses 90% of the production in Zhejiang Province. Disease incidence was approximately 90% of plants observed in affected fields. Early symptoms were yellow-to-brown, irregular-shaped lesions on the leaf margin or tip. After several days, lesions expanded along the mid-vein until the entire leaf was destroyed. Blighted leaves turned grayish to dark brown and withered, and severely affected plants died. Eight fungal isolates were recovered from symptomatic C. wenyujin leaves, collected from eight different fields, on potato dextrose agar (PDA). These fungal colonies were initially white, becoming light to dark gray and produced black, spherical to subspherical, single-celled conidia (14 to 17 × 12 to 15 μm), which were borne on a hyaline vesicle at the tip of the conidiophores. On the basis of these morphological features, the isolates appeared to be similar to Nigrospora sphaerica (2). Strain ZJW-1 was selected as a representative for molecular identification. Genomic DNA was extracted from the isolate, and the internal transcribed spacer (ITS) region of the ribosomal DNA (ITS1-5.8S-ITS2) was amplified using ITS1 (5′-TCCGTAGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) primers (3). The ITS region was further cloned and sequenced (GenBank Accession No. JF738028) and was 99% identical to N. sphaerica (GenBank Accession No. FJ478134.1). On the basis of morphological data and the ITS rDNA sequence, the isolate was determined to be N. sphaerica. Pathogenicity tests were conducted on four leaves of four C. wenyujin plants by placing agar pieces (5 mm in diameter) from 8-day-old cultures on pushpin-wounded leaves. An equal number of control plants were wounded and inoculated with noncolonized PDA agar pieces. Plants were placed in moist chambers at 25°C with a 12-h photoperiod. Brown-to-black lesions were observed on wounded leaves after 3 days and expanded to an average of 56 × 40 mm 15 days after inoculation. No symptoms developed on the control leaves. The pathogen was reisolated from the margins of necrotic tissues but not from the controls. The pathogen has been reported as a leaf pathogen on several hosts worldwide (1). To our knowledge, this is the first report of N. sphaerica as a leaf pathogen of C. wenyujin in China. Future research will focus primarily on management of this disease. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases, Systematic Mycology and Microbiology Laboratory, USDA-ARS, Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , March 31, 2011. (2) E. W. Mason. Trans. Brit. Mycol. Soc. 12:152, 1927. (3) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990. (4) J. Zhao et al. Molecules 15:7547, 2010.

Download Full-text

First Report of Leaf Blight Caused by Septoria allii on Garlic Chives in Korea

Plant Disease ◽

10.1094/pdis-08-12-0809-pdn ◽

2013 ◽

Vol 97 (1) ◽

pp. 147-147

Author(s):

J. H. Park ◽

S. E. Cho ◽

K. S. Han ◽

H. D. Shin

Keyword(s):

Disease Incidence ◽

Morphological Characteristics ◽

Its Region ◽

Leaf Blight ◽

Plant Diseases ◽

Cultivated Plants ◽

Sequence Information ◽

Conidial Suspension ◽

Korean Society ◽

First Report

Garlic chives, Allium tuberosum Roth., are widely cultivated in Asia and are the fourth most important Allium crop in Korea. In June 2011, a leaf blight of garlic chives associated with a Septoria spp. was observed on an organic farm in Hongcheon County, Korea. Similar symptoms were also found in fields within Samcheok City and Yangku County of Korea during the 2011 and 2012 seasons. Disease incidence (percentage of plants affected) was 5 to 10% in organic farms surveyed. Diseased voucher specimens (n = 5) were deposited at the Korea University Herbarium (KUS). The disease first appeared as yellowish specks on leaves, expanding to cause a leaf tip dieback. Half of the leaves may be diseased within a week, especially during wet weather. Pycnidia were directly observed in leaf lesions. Pycnidia were amphigenous, but mostly epigenous, scattered, dark brown to rusty brown, globose, embedded in host tissue or partly erumpent, separate, unilocular, 50 to 150 μm in diameter, with ostioles of 20 to 40 μm in diameter. Conidia were acicular, straight to sub-straight, truncate at the base, obtuse at the apex, hyaline, aguttulate, 22 to 44 × 1.8 to 3 μm, mostly 3-septate, occasionally 1- or 2-septate. These morphological characteristics matched those of Septoria allii Moesz, which is differentiated from S. alliacea on conidial dimensions (50 to 60 μm long) (1,2). A monoconidial isolate was cultured on potato dextrose agar (PDA). Two isolates have been deposited in the Korean Agricultural Culture Collection (Accession Nos. KACC46119 and 46688). Genomic DNA was extracted using the DNeasy Plant Mini DNA Extraction Kit (Qiagen Inc., Valencia, CA). The internal transcribed spacer (ITS) region of rDNA was amplified using the ITS1/ITS4 primers and sequenced. The resulting sequence of 482-bp was deposited in GenBank (JX531648 and JX531649). ITS sequence information was at least 99% similar to those of many Septoria species, however no information was available for S. allii. Pathogenicity was tested by spraying leaves of three potted young plants with a conidial suspension (2 × 105 conidia/ml), which was harvested from a 4-week-old culture on PDA. Control leaves were sprayed with sterile water. The plants were placed in humid chambers (relative humidity 100%) for the first 48 h. After 7 days, typical leaf blight symptoms started to develop on the leaves of inoculated plants. S. allii was reisolated from the lesions of inoculated plants, confirming Koch's postulates. No symptoms were observed on control plants. The host-parasite association of A. tuberosum and S. allii has been known only from China (1). S. alliacea has been recorded on several species of Allium, e.g. A. cepa, A. chinense, A. fistulosum, and A. tuberosum from Japan (4) and A. cepa from Korea (3). To the best of our knowledge, this is the first report of S. allii on garlic chives. No diseased plants were observed in commercial fields of garlic chives which involved regular application of fungicides. The disease therefore seems to be limited to organic garlic chive production. References: (1) P. K. Chi et al. Fungous Diseases on Cultivated Plants of Jilin Province, Science Press, Beijing, China, 1966. (2) P. A. Saccardo. Sylloge Fungorum Omnium Hucusque Congnitorum. XXV. Berlin, 1931. (3) The Korean Society of Plant Pathology. List of Plant Diseases in Korea, Suwon, Korea, 2009. (4) The Phytopathological Society of Japan. Common Names of Plant Diseases in Japan, Tokyo, Japan, 2000.

Download Full-text

First Report of Nigrospora Leaf Blight on Sesame Caused by Nigrospora sphaerica in China

Plant Disease ◽

10.1094/pdis-07-13-0684-pdn ◽

2014 ◽

Vol 98 (6) ◽

pp. 842-842 ◽

Cited By ~ 3

Author(s):

H. Zhao ◽

H. Y. Liu ◽

X. S. Yang ◽

Y. X. Liu ◽

Y. X. Ni ◽

...

Keyword(s):

Morphological Characteristics ◽

Leaf Blight ◽

Morphological Data ◽

Its2 Region ◽

Oilseed Crop ◽

Conidial Suspension ◽

First Report ◽

Initial Symptoms ◽

Central Regions ◽

Leaf Pathogen

Sesame (Sesamum indicum L.) is an important oilseed crop widely grown in the central regions of China. A new leaf blight has increasingly been observed in sesame fields in Anhui, Hubei, and Henan provinces since 2010. Approximately 30 to 40% of the plants were symptomatic in the affected fields. Initial symptoms were yellow to brown, irregularly shaped lesions. Lesions later expanded and the affected leaves tuned grayish to dark brown and wilted, with a layer of whitish mycelial growth on the underside. Severe blighting caused the center of lesions to fall out, leaving holes in the leaves. Sections of symptomatic leaf tissues were surface-sterilized in 75% ethanol for 30 s, then in 1% HgCl2 for 30 s, rinsed three times in sterile distilled water, and plated onto potato dextrose agar (PDA). The resulting fungal colonies were initially white, and then became grayish-brown with sporulation. Conidia were single-celled, black, smooth, spherical, 14.2 to 19.8 μm (average 17.1 μm) in diameter, and borne on a hyaline vesicle at the tip of each conidiophore. Morphological characteristics of the isolates were similar to those of Nigrospora sphaerica (1). To verify the identification based on morphological features, the ITS1-5.8S-ITS2 region of the ribosomal RNA was amplified using ITS1 (5′-TCCGTAGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′) primers (3), and then sequenced and compared to the GenBank database through a BLAST search. Comparison of the sequence revealed 100% similarity to N. sphaerica (GenBank Accession No. JF817271.1). On the basis of morphological data and the ITS rDNA sequence, the isolate was determined to be N. sphaerica. Pathogenicity tests were conducted using fresh and healthy sesame leaves of 10 plants. A conidial suspension (106 conidia/ml) collected from a 7-day-old culture on PDA was used for inoculation. Leaves of 10 plants were spray-inoculated with the spore suspension at the 6-week-old growth stage, and an additional 10 plants were sprayed with sterile water. Inoculated plants were covered with polyethylene bags to maintain high humidity. Plants were kept at 28°C and observed for symptom every day. Ten to 15 days after inoculation, inoculated leaves developed blight symptoms similar to those observed on naturally infected leaves. No symptoms were observed on the control leaves. N. sphaerica was re-isolated from the inoculated leaves, thus fulfilling Koch's postulates. N. sphaerica has been reported as a leaf pathogen on several hosts worldwide (2). To our knowledge, this is the first report of Nigrospora leaf blight on sesame caused by N. sphaerica in China. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. CMI, Kew, Surrey, UK, 1971. (2) D. F. Farr and A. Y. Rossman. Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ . July 01, 2013. (3) M. A. Innis et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

Download Full-text

First Report of Leaf Blight on Duying Caused by Phyllosticta anacardiacearum in China

Plant Disease ◽

10.1094/pdis-93-5-0546b ◽

2009 ◽

Vol 93 (5) ◽

pp. 546-546 ◽

Cited By ~ 2

Author(s):

B. G. Lou ◽

Y. D. Xu ◽

C. Sun ◽

X. M. Lou

Keyword(s):

Southern China ◽

Disease Incidence ◽

Its Region ◽

Culture Collection ◽

Leaf Blight ◽

Its Sequences ◽

Dead Leaf ◽

Conidial Suspension ◽

First Report ◽

Branch Dieback

Duying (Elaeocarpus glabripetalus Merr.; Elaeocarpaceae) is widely cultivated as an ornamental tree of commercial importance in southern China. From 2003 to 2008, severe outbreaks of Duying leaf blight occurred in the Hangzhou area, Zhejiang Province. Disease incidence was greater than 20% and mainly infected young leaves and shoots in the spring and autumn. Severely infected leaves and shoots died and eventually led to branch dieback. The overall growth decline of affected trees occurs over 4 to 6 years before tree death. Infection symptoms are characterized by grayish, round, semicircular- or irregular-shaped spots (5 mm to 5 cm long) with dark brown borders and the appearance of black, granular pycnidia within the dead leaf tissues. The primary infection zones are commonly observed on the leaf margins and apices, are brown, up to 2 mm in diameter, and often surrounded by a yellow zone. Pycnidia were globose and 122 to 127 μm (average 123.5 μm) in diameter. A fungus was consistently isolated from symptomatic tissues on potato dextrose agar (PDA). Ash-black pycnidia appeared on PDA after 10 days. Ascospores developed on modified PDA (1 liter of PDA + 20 g of Duying leaves) after 18 days. Conidiogenous cells were cylindrical to obpyriform. The hyaline conidia were obovoid and guttulate, 10 to 13 × 6 to 8 μm (average 11.5 × 7.5 μm), and usually surrounded by a mucilaginous sheath with a hyaline apical appendage that was 5 to 8 μm long. Pseudothecia were solitary and subglobose with long necks. Asci were 45 to 70 × 7.5 to 12 μm (average 62.5 × 10.8 μm). Ascospores were 12 to 13 × 4 to 5 μm with rounded apices and hyaline, mucilaginous, apical caps. The fungus was morphologically identified as Phyllosticta anacardiacearum van der Aa (teleomorph Guignardia mangiferae A. J. Roy). This identification was also confirmed by the China General Microbiological Culture Collection Center (CGMCC). Six representative fungal isolates were identified by sequencing the internal transcribed spacer (ITS) region of the rDNA and comparing the sequences with those in GenBank using BLAST searches. The ITS sequences of six cultures (GenBank Accession Nos. EU821356–EU821361) showed 100% identity with the ITS sequences of an isolate of a Phyllosticta sp. (GenBank Accession No. AF532314) (2) and G. mangiferae (GenBank Accession No. AY277717) (1). To fulfill Koch's postulates, a conidial suspension (106 conidia per ml) collected from PDA cultures (isolate phy01) was used to spray inoculate leaves of potted 3-year-old Duying trees. Inoculated trees were kept for 48 h under a polyethylene sheet cover and grown at 10 to 15°C in a greenhouse. A total of 30 leaves of five healthy trees were inoculated with the pathogen. In addition, five 3-year-old trees were sprayed with sterile water to serve as uninoculated controls. After 10 to 14 days, inoculated leaves showed infection symptoms resembling those observed on Duying trees naturally infected with P. anacardiacearum. The pathogen was reisolated from the margins of necrotic tissues, but not from controls. To our knowledge, this is the first report of leaf blight on E. glabripetalus caused by P. anacardiacearum in China. Reference: (1) F. R. Katia et al. Mycol. Res. 108:45, 2004. (2) A. K. Pandey et al. Mycol. Res. 107:439, 2003.

Download Full-text

First Report of Powdery Mildew on Trident Maple Caused by Sawadaea nankinensis in Korea

Plant Disease ◽

10.1094/pdis-93-12-1348c ◽

2009 ◽

Vol 93 (12) ◽

pp. 1348-1348

Author(s):

H. B. Lee ◽

C. J. Kim ◽

H. Y. Mun ◽

J. P. Hong ◽

D. A. Glawe

Keyword(s):

Powdery Mildew ◽

Its Region ◽

Agricultural Science ◽

Morphological Data ◽

First Report ◽

5.8S Rdna ◽

Rdna Sequences ◽

National University ◽

Causal Fungus ◽

Pathogenicity Tests

Trident maple (Acer buergerianum Miq.) is widely grown in Korea as an ornamental tree as well as for the art of bonsai. During 2008 and 2009, a powdery mildew was observed on trident maple plants at the campus of Chonnam National University, Gwangju, Korea. Further surveys revealed the disease to be widespread on this species in other areas including Jeonbuk and Chungnam provinces in Korea. White, superficial mycelia were observed on young shoots and leaves early in spring. Both macroconidia and microconidia were produced beginning in May and conidial production continued through the summer into September and October. Production of chasmothecia was observed starting in September and continued into October. Macroconidia were produced in chains that were sinuate in outline. Individual macroconidia were barrel shaped and 23.4 to 30.0 (26.6) × 15.6 to 21.1 (18.1) μm. Foot cells of macroconidial conidiophores were 26.7 to 110.7 (48) × 7.1 to 11.2 (8.8) μm with one to five following cells. Microconidia were broadly ellipsoidal to subglobose and 8.9 to 12.5 (10.5) × 4.3 to 5.8 (5.1) μm. Chasmothecia typically were formed on adaxial leaf surfaces and 193.2 to 238.1 (216.8) μm in diameter. Appendages bore uncinate to circinate apices and were 176.8 to 267.7 (211.5) × 4.3 to 8.0 (6.2) μm. From extracted genomic DNA, internal transcribed spacer (ITS) region inclusive of 5.8S rDNA was amplified with ITS1F (5′-CTTGGTCATTTAGAGGAAGT-3′) and LR5F (5′-GCTATCCTGAGGGAAAC-3′) primers. The causal fungus was determined to be Sawadaea nankinensis (F.L. Tai) S. Takam. & U. Braun (2) on the basis of morphological data and ITS rDNA sequences. A BLAST search of GenBank with an ITS sequence from this fungus determined that the five sequences exhibiting the highest max score values (1,811 to 2,004) were from S. nankinensis; these sequences produced max ident values from 94% to 99%. In contrast, max score and max ident values from sequences of other Sawadaea spp. were lower, including scores of 1,063 and 98% similarity for S. polyfida var. japonica, 915 and 97% for S. tulasnei, and 913 and 97% for S. bicornis. Pathogenicity tests were conducted on field-grown plants in two replicates. These plants were inoculated with a paintbrush to apply conidia (~5 × 106/ml) collected from powdery-mildew-infected leaves. Inoculated plants developed powdery mildew symptoms within 5 days of inoculation and resembled those observed on naturally infected plants. S. nankinensis (synonym Uncinula nankinensis) was first reported on A. buergerianum from China in 1930 (2). Recently, S. nankinensis (F.L. Tai) S. Takam & U. Braun was reported to occur on A. buergerianum in Japan (3). Until now, three Sawadaea spp. (S. bicornis (Wallr.) Homma, S. negundinis Homma, and S. tulasnei (Fuckel) Homma) have been reported to cause powdery mildew on A. ginnala, but only S. bicornis (= U. circinata Cooke & Peck) has been reported to cause powdery mildew on A. ginnala in Korea (1). However, no Sawadaea sp. previously was reported to cause powdery mildew on A. buergerianum. To our knowledge, this is the first report of powdery mildew on trident maple (A. buergerianum) caused by S. nankinensis in Korea. References: (1) H. D. Shin. Erysiphaceae of Korea. National Institute of Agricultural Science and Technology, 2000. (2) F. L. Tai. Page 1517 in: Sylloge Fungorum Sinicorum. Science Press, Academia Sinica, Peking, 1979. (3) S. Takamatsu et al. Mycoscience 49:161, 2008.

Download Full-text

First Report of Anthracnose on Jerusalem Cherry Caused by Colletotrichum liaoningense in Shandong, China

Plant Disease ◽

10.1094/pdis-01-21-0124-pdn ◽

2021 ◽

Author(s):

Yun Liu ◽

Fei An ◽

Yujiao Zhang ◽

Cuicui Fu ◽

Yuebo Su

Keyword(s):

Disease Incidence ◽

Its Region ◽

Molecular Characteristics ◽

Conidial Suspension ◽

Transparent Plastic ◽

First Report ◽

Plastic Bags ◽

White Spots ◽

Pure Cultures ◽

Pathogenicity Tests

Jerusalem cherry (Solanum pseudocapsicum), which belongs to the genus Solanum and the family Solanaceae, possesses high ornamental value and is widely cultivated as an indoor ornament due to its bright red berries at maturity (Xu et al., 2018). In September 2019, leaf spot was detected on jerusalem cherry plants in Yuxiu Park, Shizhong district, Jinan, Shandong Province. Field surveys were done in a 1/15 ha park. Disease incidence was estimated at approximately 18% across the survey area. Foliar symptoms began as small white spots. As the disease progressed, lesions expanded and merged, and developed into large irregular white spots, with pale grey edge. At last, lesions were densely distributed throughout the leaves. To isolate the pathogen, twenty leaf tissues (5 × 5 mm) were cut from the border between diseased and healthy tissue, surface disinfected in 75% alcohol for 15 s, soaked in 0.1% mercuric chloride for 1 min, washed with sterile distilled water three times, and cultured on potato dextrose agar (PDA) at 25°C. Nineteen fungal isolates were obtained and were single-spored to obtain pure cultures. The colony of LCL7, a representative isolate, on PDA was initially white to orange, but turned black after 3 to 4 days incubation with black conidial masses. Conidia were single-celled, hyaline, straight, cylindrical, apex obtuse, and ranged from 13.4 to 18.3 × 3.2 to 4.9 μm (n = 50) （Diao et al., 2017）. To validate the species identification, rDNA internal transcribed spacer (ITS) region (White et al., 1990), and the partial sequences of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), actin (ACT), β-tubulin (TUB2), and chitin synthase (CHS-1) (Damm et al., 2019; He et al., 2019), were amplified and sequenced. The ITS, GAPDH, ACT, TUB2, and CHS-1 sequences of isolate LCL7 were submitted to GenBank (MW221320, MW227217, MW227218, MW227219, and MW266988, respectively). ITS, ACT, TUB2, and CHS-1 BLAST showed 99-100% homology with sequences of Colletotrichum liaoningense (ITS, 100% to MH636504; ACT, 100% to MH622582; TUB2, 99.56% to MH622714, CHS-1, 99.33% to MH622446, respectively), although GAPDH showed 93.98% homology with sequence MH681383 (234/249bp). Neighbor-joining tree based on concatenated sequences of the five genes was constructed using MEGA7.0. The results showed the isolate was closely related to C. liaoningense. Based on morphological and molecular characteristics, the isolate LCL7 was identified as C. liaoningense. Pathogenicity tests were performed by spraying a conidial suspension (1 × 105 conidia/mL) on ten two-year-old healthy jerusalem cherry plants. Ten other plants with sterile water served as controls. All samples were incubated in a growth chamber at 25±2°C and transparent plastic bags to keep relative humidity high for 2 days. All inoculated plants showed symptoms similar to those observed in the field after 21 days, but no disease occurred on control plants. The same fungus was successfully reisolated from inoculated leaves and reidentified based on morphology and molecular characteristics, and the fungus was not isolated from the control plants, thus confirming Koch's postulates. Pathogenicity tests were repeated twice. C. liaoningense can cause anthracnose in chili and mango in China (Diao et al., 2017; Li et al., 2019).To our knowledge, this is the first report of anthracnose on jerusalem cherry caused by C. liaoningense in China, which influences ornamental value and reduces market value. Identification of the causes of the disease will help develop effective strategies for managing this disease.

Download Full-text

First Report of Branch Rot of Lonicera japonica Caused by Sclerotium delphinii in China

Plant Disease ◽

10.1094/pdis-01-14-0053-pdn ◽

2014 ◽

Vol 98 (8) ◽

pp. 1155-1155

Author(s):

M. Zhang ◽

X. J. Wang ◽

Y. Li ◽

Y. H. Geng ◽

H. Y. Wu

Keyword(s):

Disease Incidence ◽

Its Region ◽

Lonicera Japonica ◽

First Report ◽

Plastic Bags ◽

Mycelial Plug ◽

Pathogenicity Tests ◽

White Mycelium ◽

Sclerotium Delphinii ◽

Stem Lesions

Honeysuckle flower (Lonicera japonica Thunb.) is a perennial, traditional Chinese medicine plant, widely cultivated in China. In early June 2013, heavy branch rot infection was observed on L. japonica in an approximately 10,000-m2 field in Linyi, Shandong, China. The disease incidence was 30 to 40%. Early symptoms appeared as small, elliptoid, pale brown lesions on the branches. Lesions expanded into 50 to 100 mm long and 3 to 7 mm wide, brown, elongated spots. The upper branches wilted after the lesions expanded around the stems. A fungus was consistently isolated from stem lesions on potato dextrose agar (PDA) that was morphologically similar to S. delphinii, with white mycelium, round to irregularly shaped reddish-brown sclerotia that were 2 to 4 mm diameter (2). The identity of the fungus was confirmed by DNA sequencing of the internal transcribed spacer (ITS) region (GenBank Accession No. KJ145328), which was 99% homologous to those of other S. delphinii isolates (JN241578 and AB075314) (1). Pathogenicity tests were conducted with three 2-year-old seedlings grown in 20-cm-diameter pots at 25 to 30°C during experiments in greenhouse. Ten branches from the three plants pricked by needle were inoculated with a mycelial plug (0.4 cm diameter) harvested from the periphery of a 4-day-old colony. An equal number of branches pricked by needle serving as controls were mock-inoculated with plugs of PDA medium. Inoculated branches were covered with plastic bags for 24 h to maintain high relative humidity and incubated at about 25°C. Plugs were removed 48 h after inoculation. After 3 days, nine inoculated branches showed symptoms identical to those observed in the field under natural conditions, whereas controls remained symptom-free. Re-isolation of the fungus from lesions on inoculated branches confirmed that the causal agent was S. delphinii. Pathogenicity tests were repeated three times by the same methods with the same results. To our knowledge, this is the first report of S. delphinii infecting Lonicera japonica in China. References: (1) I. Okabe and N. Matsumoto. Mycol. Res. 107:164, 2003. (2) Z. K. Punja and A. Damiani. Mycologia. 88:694, 1996.

Download Full-text

First Report of Black Spot Disease Caused by Alternaria alternata on Cherry Fruits in China

Plant Disease ◽

10.1094/pdis-04-12-0416-pdn ◽

2012 ◽

Vol 96 (10) ◽

pp. 1580-1580 ◽

Cited By ~ 6

Author(s):

Y. Z. Zhao ◽

Z. H. Liu

Keyword(s):

Alternaria Alternata ◽

Disease Incidence ◽

Black Spot ◽

Its Region ◽

Liaoning Province ◽

Broad Host Range ◽

Pathogenicity Test ◽

First Report ◽

Initial Stage ◽

Pathogenicity Tests

Cherry (Cerasus pseudocerasus) has become an economically important fruit in China in recent years. In June 2010, fruit spots were discovered on fruit grown in Dalian City, Liaoning Province, China and 30% of local-orchard trees were infected with the disease, reducing yield and fruit quality. Disease incidence increased up to 75% in 2011. At the initial stage of the infection, some small, light brown spots appeared on the fruit that gradually became round or irregular and dark brown, and a black-brown concentric ring formed in the advanced stage of the infection. As disease progressed, the lesions expanded, causing the fruit surface to become pitted, withered, and dead. The pathogen was isolated from infected fruit of four orchards by a tissue isolation method (1) and cultured on potato dextrose agar (PDA) at 25°C in the dark for one week. Colonies on PDA were initially white and became grayish brown over time. Conidiophores were single or fasciculate, straight or knee curved, gray-brown with regular septa, branched or unbranched, and 12.5 to 90.0 × 2.0 to 5.0 μm. Conidia were oval, obclavate, or obpyriform, brown or dark brown, surface smooth or spinulose with short columnar beaks, and 20.0 to 42.0 × 7.5 to 14.5 μm with three to eight transverse septa and zero to three longitudinal or oblique septa. The sporulation pattern appeared in bush branches. According to the morphology, the pathogen was identified as Alternaria alternata (Fr:Fr.) Keissler (2,3). The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS1/ITS4 and the ITS sequence was 99% identical to A. alternata (GenBank Accession No. FJ228163). Pathogenicity tests were performed on detached, asymptomatic fruit. Six fruit were inoculated by placing a PDA plug containing mycelia on the upper surface of the fruit. Another six fruit received sterile PDA plugs. Fruit were cultured in petri dishes with a 12-h photoperiod at 25°C and 90% relative humidity. Black spot symptoms were observed on inoculated fruit but not control fruit after 5 days. The pathogen was reisolated from inoculated fruit and confirmed to be A. alternata. The pathogenicity test was repeated once. A. alternata has a broad host range, but to our knowledge, this is the first report of A. alternata infecting cherries in China. References: (1) Z. D. Fang. Research Methods of Plant Disease, 124, 1998. (2) E. G. Simmons. Alternaria themes and variations. Mycotaxon 37: 79, 1990. (3) T. Y. Zhang et al. Fungi Notes–Genera Alternaria in China, 16:32, 2003.

Download Full-text

First Report of Leaf Blight of Adenophora triphylla var. japonica caused by Pseudomonas viridiflava in Korea

Plant Disease ◽

10.1094/pdis-11-20-2506-pdn ◽

2021 ◽

Author(s):

Seunghwan Kim ◽

Hyeok Tae Kwon ◽

Youn Mi Lee ◽

Chung Ryul Jung ◽

Balaraju Kotnala ◽

...

Keyword(s):

16S Rdna ◽

Disease Incidence ◽

Morphological Characteristics ◽

Leaf Blight ◽

Identification System ◽

Post Inoculation ◽

First Report ◽

Microbial Identification ◽

Pseudomonas Viridiflava ◽

Pathogenicity Tests

Severe disease with leaf spots and necrotic symptoms were observed in Adenophora triphylla var. japonica (Regel) Hara (A. triphylla) during the survey in July 2020 on a field in Andong, Gyeongbuk province, Korea. It is a highly valued medicinal plant used to treat various diseases, including cough, cancer, and obesity. The infected plants initially showed spots with halo lesions, at later stages, enlarged and spread to the leaves, which the lesions becoming yellowing and chlorotic (Fig. 1). In some areas, disease incidence was up to 15% of the plants. The symptomatic samples were collected from A. triphylla and cut into 4 to 5 mm squares, surface-sterilized in 1% sodium hypochlorite for 1 min, rinsed three times, and macerated in sterile distilled water (SDW). They were spread onto nutrient agar (NA) plates and incubated at 28°C for 3 days. The representative bacterial strains selected for identification showed fluorescent colonies on King’s medium B (KB). Fifteen isolates from independent samples were subjected to biochemical and pathogenicity tests. The isolates induced a hypersensitive reaction in tobacco leaves, gave a reaction in the anaerobe respiratory test, and were negative for levan, oxidase, arginine dihydrolase, gelatin hydrolysis, aesculin hydrolysis, and starch hydrolysis. The isolated strains presented the following LOPAT profile: – – + – +. The Biolog GN2 microplate and the Release 4.20 system putatively found the isolate to exhibit 93% similarity with the bacterium, Pseudomonas viridiflava. Likewise, analysis of FAME profiles using the Microbial identification system (Sherlock version 3.1) also characterized the representative bacterial strain as P. viridiflava with 87% similarity. The genomic DNA of the isolate was extracted, and the 16S rDNA sequence was amplified with a universal bacterial primer set (27F and 1492R). The sequence was submitted to GenBank under the accession number MT975233. BLASTn analysis yielded 99.79% identity with P. viridiflava strain RT228.1b (accession no. AY604846.1) and 99.72% similarity with P. viridiflava KNOX249.1b strain (accession no. AY604848.1). Phylogenetic dendrogram constructed from the comparative analysis of 16S rDNA gene sequences showing the relationship between P. viridiflava GYUN274 and related Pseudomonas species (Fig. 2). Pathogenicity tests were conducted three times on seedling of A. triphylla by spraying 50 ml of bacterial suspensions of a 24-h culture in KB medium (108 CFU/ml). The leaves inoculated with SDW alone did not develop symptoms; however, the plants treated with isolated bacterial suspensions developed halo and blight symptoms similar to those observed in the field 7 days post-inoculation. Finally, Koch’s postulates were verified by re-isolating P. viridiflava from all symptomatic tissues and determined to be morphologically identical to the original isolates. To our knowledge, this is the first report of leaf blight disease of A. triphylla caused by P. viridiflava in Korea. Based on the observed symptoms, and identification by morphological characteristics, molecular data, and pathogenicity against the host plant, the proper control measures can be identified in future studies.

Download Full-text

First Report of Dollar Spot of Sandbur Caused by Sclerotinia homoeocarpa in Oklahoma

Plant Disease ◽

10.1094/pdis-03-14-0244-pdn ◽

2014 ◽

Vol 98 (8) ◽

pp. 1160-1160

Author(s):

F. Flores ◽

N. R. Walker

Keyword(s):

Warm Season ◽

Its Region ◽

Small Subunit ◽

Type I ◽

Academic Press ◽

Sclerotinia Homoeocarpa ◽

Dollar Spot ◽

First Report ◽

Small Subunit Rdna ◽

Disturbed Soils

Sandbur (Cenchrus incertus Curtis) is a warm-season, annual, noxious, grassy weed native to southern North America. It is common in sandy, disturbed soils and can also be found in home lawns and sport fields where low turf density facilitates its establishment. In July 2013, after a period of frequent rainfall and heavy dew, symptoms of dollar spot-like lesions (1) were observed on sandbur plants growing in a mixed stand of turf-type and native warm-season grasses in Logan County, Oklahoma. Lesions, frequently associated with leaf sheaths, were tan and surrounded by a dark margin. Symptomatic leaves were surface sterilized and plated on potato dextrose agar amended with 10 ppm rifampicin, 250 ppm ampicillin, and 5 ppm fenpropathrin. After incubation, a fungus morphologically identical to Sclerotinia homoeocarpa Bennett was consistently isolated. The nuclear ribosomal internal transcribed spacer (ITS) region of two different isolates, SCL2 and SCL3, were amplified using primers ITS4 and ITS5 (2). The DNA products were sequenced and BLAST analyses were used to compare sequences with those in GenBank. The sequence for isolate SLC2 was 869 bp, contained a type I intron in the 18S small subunit rDNA, and was identical to accession EU123803. The ITS sequence for isolate SLC3 was 535 bp and identical to accession EU123802. Twenty-five-day-old seedlings of C. incertus were inoculated by placing 5-mm-diameter agar plugs, colonized by mycelia of each S. homoeocarpa isolate, onto two of the plants' leaves. Plugs were held in place with Parafilm. Two plants were inoculated with each isolate and sterile agar plugs were placed on two leaves of another seedling as control. Plants were incubated in a dew chamber at 20°C and a 12-h photoperiod. After 3 days of incubation, water-soaked lesions surrounded by a dark margin appeared on inoculated plants only. Fungi that were later identified as S. homoeocarpa isolates SLC2 and SLC3 by sequencing of the ITS region were re-isolated from symptomatic leaves, fulfilling Koch's postulates. To our knowledge, this is the first report of dollar spot on sandbur. References: (1) R. W. Smiley et al. Page 22 in: Compendium of Turfgrass Diseases. 3rd ed. The American Phytopathological Society, St. Paul, MN, 2005. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990.

Download Full-text

First Report of Leaf Blight of Japanese Yew Caused by Pestalotiopsis microspora in Korea

Plant Disease ◽

10.1094/pdis-08-13-0821-pdn ◽

2014 ◽

Vol 98 (5) ◽

pp. 691-691 ◽

Cited By ~ 2

Author(s):

Y. H. Jeon ◽

W. Cheon

Keyword(s):

Dna Sequences ◽

Apical Cell ◽

Morphological Characteristics ◽

Leaf Blight ◽

Economic Damage ◽

Leaf Margin ◽

Conidial Suspension ◽

First Report ◽

Pestalotiopsis Microspora ◽

Large Trees

Worldwide, Japanese yew (Taxus cuspidata Sieb. & Zucc.) is a popular garden tree, with large trees also being used for timber. In July 2012, leaf blight was observed on 10% of Japanese yew seedling leaves planted in a 500-m2 field in Andong, Gyeongsangbuk-do Province, South Korea. Typical symptoms included small, brown lesions that were first visible on the leaf margin, which enlarged and coalesced into the leaf becoming brown and blighted. To isolate potential pathogens from infected leaves, small sections of leaf tissue (5 to 10 mm2) were excised from lesion margins. Eight fungi were isolated from eight symptomatic trees, respectively. These fungi were hyphal tipped twice and transferred to potato dextrose agar (PDA) plates for incubation at 25°C. After 7 days, the fungi produced circular mats of white aerial mycelia. After 12 days, black acervuli containing slimy spore masses formed over the mycelial mats. Two representative isolates were further characterized. Their conidia were straight or slightly curved, fusiform to clavate, five-celled with constrictions at the septa, and 17.4 to 28.5 × 5.8 to 7.1 μm. Two to four 19.8- to 30.7-μm-long hyaline filamentous appendages (mostly three appendages) were attached to each apical cell, whereas one 3.7- to 7.1-μm-long hyaline appendage was attached to each basal cell, matching the description for Pestalotiopsis microspora (2). The pathogenicity of the two isolates was tested using 2-year-old plants (T. cuspidata var. nana Rehder; three plants per isolate) in 30-cm-diameter pots filled with soil under greenhouse conditions. The plants were inoculated by spraying the leaves with an atomizer with a conidial suspension (105 conidia/ml; ~50 ml on each plant) cultured for 10 days on PDA. As a control, three plants were inoculated with sterilized water. The plants were covered with plastic bags for 72 h to maintain high relative humidity (24 to 28°C). At 20 days after inoculation, small dark lesions enlarged into brown blight similar to that observed on naturally infected leaves. P. microspora was isolated from all inoculated plants, but not the controls. The fungus was confirmed by molecular analysis of the 5.8S subunit and flanking internal transcribed spaces (ITS1 and ITS2) of rDNA amplified from DNA extracted from single-spore cultures, and amplified with the ITS1/ITS4 primers and sequenced as previously described (4). Sequences were compared with other DNA sequences in GenBank using a BLASTN search. The P. microspora isolates were 99% homologous to other P. microspora (DQ456865, EU279435, FJ459951, and FJ459950). The morphological characteristics, pathogenicity, and molecular data assimilated in this study corresponded with the fungus P. microspora (2). This fungus has been previously reported as the causal agent of scab disease of Psidium guajava in Hawaii, the decline of Torreya taxifolia in Florida, and the leaf blight of Reineckea carnea in China (1,3). Therefore, this study presents the first report of P. microspora as a pathogen on T. cuspidata in Korea. The degree of pathogenicity of P. microspora to the Korean garden evergreen T. cuspidata requires quantification to determine its potential economic damage and to establish effective management practices. References: (1) D. F. Farr and A. Y. Rossman, Fungal Databases, Syst. Mycol. Microbiol. Lab. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ (2) L. M. Keith et al. Plant Dis. 90:16, 2006. (3) S. S. N. Maharachchikumbura. Fungal Diversity 50:167, 2011. (4) T. J. White et al. PCR Protocols. Academic Press, San Diego, CA, 1990.

Download Full-text