Alternaria tenuissima Causing Alternaria Blight on Pigeonpea in India

Pigeonpea (Cajanus cajan (L.) Millsp.) is a major grain legume of the tropics and subtropics worldwide. In India, pigeonpea is the third most important food legume after chickpea and field pea. Blight symptoms on pigeonpea were observed in alarming proportion during the 2009 through 2011 crop seasons in Andhra Pradesh state in India. Disease incidence ranged from 20 to 80% irrespective of cultivars sown. Infected plants in the field showed symptoms on all aerial parts of the plant (leaves, stems, buds, and pods) irrespective of age of the plant and leaves. Symptoms on leaves were small, circular, necrotic spots that developed quickly forming typical concentric rings (1). Later, these spots coalesced and caused blighting of leaves. Spots were initially light brown and later turned dark brown. On stems, spots were sunken with concentric rings. In severe infection, defoliation and drying of infected leaves, branches, and flower buds was observed. The fungus was successfully isolated from all the infected plant parts (leaves, stem, buds, and pods) on potato dextrose agar (PDA) medium. After 4 to 5 days of incubation at 28 ± 1°C with a 12-h photoperiod, the fungus produced colonies that were regular and flat. The periphery of the colony was olive green with a black center. Monoconidial isolations were used to establish a pure culture of the fungus. Conidiophores were short, arising singly, and were 8.86 mm long and 2.97 mm thick. Conidia varied from 15.78 to 28.70 mm long and 8.03 to 13.47 mm wide. Very small beak (1.6 to 3.2 mm) or no beak was observed. Horizontal and vertical septations of conidia varied from four to six and two to four, respectively. The pathogenicity test was conducted on 8- to 10-day-old pigeonpea plants of cultivar ICPL 87119 by spraying with a conidial suspension (5 × 105 conidia/ml). Inoculated plants were covered with polythene bags and kept in a greenhouse at 28 ± 1°C with a 12-h photoperiod. After 48 h, the polythene bags were removed. Ten days after inoculation, symptoms were similar to those observed in fields. This experiment was conducted twice with two independent sets of plants. No symptoms were observed in water-inoculated control plants. The fungus was reisolated from the inoculated plants. On the basis of the morphological characteristics, the pathogen was tentatively identified as Alternaria tenuissima. The identification was further confirmed by the rDNA and internal transcribed spacer (ITS) primer. The ITS region of rDNA was amplified with ITS 1 and ITS 4 primers. Both orientation sequenced amplicons (481 bp) were submitted to GenBank (Accession No. JQ074094). A BLASTn search revealed 99% similarity to A. tenuissima (Accession No. HQ343444). To our knowledge, this is the first report of molecular identification of A. tenuissima causing Alternaria blight in pigeonpea in India. Reference: (1) Kannaiyan, J. and Nene, Y. L. 1977. Trop. Grain Legume Bull. 9:34.

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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.

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Brown Culm Rot of Dendrocalamus latiflorus Munro Caused by Diaporthe guangxiensis in Sichuan Province, China

Plant Disease ◽

10.1094/pdis-04-21-0837-pdn ◽

2021 ◽

Author(s):

Wenjian Wei ◽

Han Zhang ◽

Liling Xie ◽

Han Liu ◽

Fengying Luo ◽

...

Keyword(s):

Genomic Dna ◽

Southern China ◽

Disease Incidence ◽

Its Region ◽

Sichuan Province ◽

Control Measures ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Single Spore ◽

Dendrocalamus Latiflorus

Dendrocalamus latiflorus Munro, the most widely cultivated bamboo species in southern China, has high ornamental value used in gardens, while culms are also used for buildings and as fibers and edibles (Gao et al. 2011). In June 2020, brown culm rot of bamboo was observed in Yibin city, Sichuan Province, in an area of approximately 1000 hectares. Disease incidence was approximately 60%, of which 30% of the plants had died. At the end of June, the lesions expanded but did not surround the base of the culm. From the end of June to the beginning of September, the lesions expanded upward and formed a streak, of which the color gradually deepened to purple-brown and black-brown. At the same time, the disease spots at the base of the culm also expanded horizontally. After the spots surrounded the base of the culm, the diseased bamboo died. Ten culms showing typical symptoms were collected and cut into 5×5 mm pieces at the junction of infected and healthy tissues. The tissues were sterilized for 1 to 2 min in 3% sodium hypochlorite, decontaminated in 75% alcohol for 3 to 5 min, placed on modified potato glucose agar (PDA) with streptomycin sulfate (50 μg/ml), and incubated at 26°C. Two isolates were obtained by the single-spore method (Sivan et al. 1992). The isolates both produced white round colonies similar to Diaporthe guangxiensis and two types of conidia: one was α type (5.5 to 8.2×1.0 to 2.8 µm, n=30), colourless, single-celled, undivided, and oval, containing two oil droplets; and β type (21.1 to 30.2×0.8 to 1.4 µm, n=30), colourless, single celled and hook shaped. Genomic DNA was extracted from the two isolates by using a fungal genomic DNA extraction kit (Solarbio, Beijing). The products were amplified by polymerase chain reaction (PCR) with primers for the internal transcribed spacer 1 (ITS) region (White et al. 1990), calmodulin (CAL) gene (Carbone and Kohn 1999), translation elongation factor 1-alpha (TEF) gene (Glass and Donaldson 1995) and beta-tubulin (TUB) gene (Soares et al. 2018). The amplified products were sequenced and blasted in GenBank (accession numbers MW380383, MW431318, MW431317 and MW431316 for ITS, CAL, TEF, and TUB, respectively). The ITS, CAL, TEF, and TUB sequences showed 100%, 99.33%, 100%, and 99.80% identity to D. guangxiensis JZB320094 (accession numbers MK335772.1, MK736727.1, MK523566.1, MK500168.1 in GenBank), respectively. To evaluate the pathogenicity of the isolates, five plants were each inoculated with two isolates. The cortex of potted bamboo were injured locally with sterilized needle, and the bamboo culms were inoculated with 100 μl of conidial suspension (105 cfu/ml). The surface of the inoculation wound was covered with gauze soaked with sterilized water. Five plants inoculated with sterile water were used as controls. The treated plants were maintained in a greenhouse at a temperature of 22 to 29°C and relative humidity of 70 to 80%. One month later, of all inoculated plants showed similar symptoms as those observed in the field. D. guangxiensis was re-isolated from all inoculated plants. The pathogenicity test was repeated three times with similar results. This is the first report of D. guangxiensis causing brown culm rot of D. latiflorus in China. These results will facilitate an enhanced understanding of factors affecting bamboo and the design of effective management strategies of the pathogenic species on bamboo and thus to develop corresponding control measures.

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First Report of Passalora Leaf Spot Caused by Passalora bougainvilleae on Bougainvillea in Mexico

Plant Disease ◽

10.1094/pdis-11-10-0787 ◽

2011 ◽

Vol 95 (6) ◽

pp. 775-775 ◽

Cited By ~ 1

Author(s):

V. Ayala-Escobar ◽

V. Santiago-Santiago ◽

A. Madariaga-Navarrete ◽

A. Castañeda-Vildozola ◽

C. Nava-Diaz

Keyword(s):

Uv Light ◽

Disease Incidence ◽

Morphological Characteristics ◽

The United States ◽

Pathogenicity Test ◽

Commonwealth Mycological Institute ◽

Conidial Suspension ◽

Single Spore ◽

First Report ◽

Bougainvillea Spectabilis

Bougainvillea (Bougainvillea spectabilis Willd) growing in 28 gardens during 2009 showed 100% disease incidence and 3 to 7% disease severity. Bougainvilleas with white flowers were the most affected. Symptoms consisted of light brown spots with dark brown margins visible on adaxial and abaxial sides of the leaves. Spots were circular, 2 to 7 mm in diameter, often surrounded by a chlorotic halo, and delimited by major leaf veins. Single-spore cultures were incubated at 24°C under near UV light for 7 days to obtain conidia. Pathogenicity was confirmed by spraying a conidial suspension (1 × 104 spores/ml) on leaves of potted bougainvillea plants (white, red, yellow, and purple flowers), incubating the plants in a dew chamber for 48 h and maintaining them in a greenhouse (20 to 24°C). Identical symptoms to those observed at the residential gardens appeared on inoculated plants after 45 to 60 days. The fungus was reisolated from inoculated plants that showed typical symptoms. No symptoms developed on control plants treated with sterile distilled water. The fungus produced distinct stromata that were dark brown, spherical to irregular, and 20 to 24 μm in diameter. Conidiophores were simple, born from the stromata, loose to dense fascicles, brown, straight to curved, not branched, zero to two septate, 14 × 2 μm, with two to four conspicuous and darkened scars. The conidia formed singly, were brown, broad, ellipsoid, obclavate, straight to curved with three to four septa, 40 × 4 μm, and finely verrucous with thick hilum at the end. Fungal DNA from the single-spore cultures was obtained using a commercial DNA Extraction Kit (Qiagen, Valencia, CA); ribosomal DNA was amplified with ITS5 and ITS4 primers and sequenced. The sequence was deposited at the National Center for Biotechnology Information Database (GenBank Accession Nos. HQ231216 and HQ231217). The symptoms (4), morphological characteristics (1,2,4), and pathogenicity test confirm the identity of the fungus as Passalora bougainvilleae (Muntañola) Castañeda & Braun (= Cercosporidium bougainvilleae Muntañola). This pathogen has been reported from Argentina, Brazil, Brunei, China, Cuba, El Salvador, India, Indonesia, Jamaica, Japan, Thailand, the United States, and Venezuela (3). To our knowledge, this is the first report of this disease on B. spectabilis Willd in Mexico. P. bougainvilleae may become an important disease of bougainvillea plants in tropical and subtropical areas of Mexico. References: (1) U. Braun and R. R. Castañeda. Cryptogam. Bot. 2/3:289, 1991. (2) M. B. Ellis. More Dematiaceous Hypomycetes. Commonwealth Mycological Institute, Kew, Surrey, UK, 1976. (3) C. Nakashima et al. Fungal Divers. 26:257, 2007. (4) K. L. Nechet and B. A. Halfeld-Vieira. Acta Amazonica 38:585, 2008.

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First Report of Anthracnose of Tricyrtis macropoda Caused by Colletotrichum gloeosporioides in Korea

Plant Disease ◽

10.1094/pdis-03-12-0277-pdn ◽

2012 ◽

Vol 96 (7) ◽

pp. 1070-1070 ◽

Cited By ~ 1

Author(s):

J. H. Park ◽

K. S. Han ◽

Y. D. Kwon ◽

H. D. Shin

Keyword(s):

Colletotrichum Gloeosporioides ◽

Morphological Characteristics ◽

Its Region ◽

Culture Collection ◽

Perennial Herb ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Natural Habitats ◽

First Report ◽

Small Water

Tricyrtis macropoda Miq. (syn. T. dilatata Nakai), known as speckled toadlily, is a perennial herb native to China, Japan, and Korea. The plant has been highly praised for its beautiful flowers and rare populations in natural habitats. In September 2006, several dozen plants were heavily damaged by leaf spots and blight in cultivated plantings in the city of Pocheon, Korea. The infections with the same symptoms were repeated every year. In July 2011, the same symptoms were found on T. macropoda in the cities of Gapyeong and Osan, Korea. The leaf lesions began as small, water-soaked, pale greenish to grayish spots, which enlarged to form concentric rings and ultimately coalesced. A number of blackish acervuli were formed in the lesions. Acervuli were mostly epiphyllous, circular to ellipsoid, and 40 to 200 μm in diameter. Setae were two- to three-septate, dark brown at the base, paler upwards, acicular, and up to 100 μm long. Conidia (n = 30) were long obclavate to oblong-elliptical, sometimes fusiform-elliptical, guttulate, hyaline, and 12 to 20 × 4 to 6.5 μm (mean 15.4 × 5.2 μm). These morphological characteristics of the fungus were consistent with the description of Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. (2). Voucher specimens (n = 7) were deposited in the Korea University herbarium (KUS). Two isolates, KACC46374 (ex KUS-F25916) and KACC46405 (ex KUS-F26063), were deposited in the Korean Agricultural Culture Collection. Fungal DNA was extracted and the complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced. The resulting sequences of 549 bp were deposited in Genbank (Accession Nos. JQ619480 and JQ619481). They showed 100% similarity with a sequence of C. gloeosporioides (EU32619). Isolate KACC46374 was used in a pathogenicity test. Inoculum was prepared by harvesting conidia from 3-week-old cultures on potato dextrose agar. A conidial suspension (2 × 106 conidia/ml) was sprayed onto 15 leaves of three plants. Three noninoculated plants served as controls. Plants were covered with plastic bags to maintain 100% relative humidity for 24 h and then kept in a greenhouse (22 to 28°C and 70 to 80% RH). After 5 days, typical leaf spot symptoms, identical to the ones observed in the field, started to develop on the leaves of inoculated plants. No symptoms were observed on control plants. C. gloeosporioides was reisolated from the lesions of inoculated plants, thus fulfilling Koch's postulates. An anthracnose associated with C. tricyrtii (Teng) Teng was recorded on T. formosana and T. latifolia in China (3) and on T. formosana in Taiwan (1), respectively, without etiological studies. The morphological features of C. tricyrtii are within the variation of C. gloeosporioides (2). To our knowledge, this is the first report of anthracnose of T. macropoda. This report has significance to indigenous plant resource conservation managers and scientists because T. macropoda has been listed as one of the 126 “Rare and Endangered Plants” by the Korea Forest Service since 1991. References: (1) K. Sawada. Rep. Dept. Agric. Gov. Res. Inst. Formosa 87: 1, 1944. (2) B. C. Sutton. Pages 1–27 in: Colletotrichum Biology, Pathology and Control. J. A. Bailey and M. J. Jeger, eds. CAB International, Wallingford, U.K. 1992. (3) S. C. Teng. Contrib. Biol. Lab. Sci. Soc. China 8:36, 1932.

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First Report of Fusarium Wilt in Blueberry (Vaccinium corymbosum) Caused by Fusarium oxysporum in China

Plant Disease ◽

10.1094/pdis-02-14-0167-pdn ◽

2014 ◽

Vol 98 (8) ◽

pp. 1158-1158 ◽

Cited By ~ 1

Author(s):

Y. H. Liu ◽

T. Lin ◽

C. S. Ye ◽

C. Q. Zhang

Keyword(s):

Fusarium Oxysporum ◽

Infected Plant ◽

Morphological Characteristics ◽

Vaccinium Corymbosum ◽

Morphological Characterization ◽

Internal Transcribed Spacers ◽

Fluorescent Light ◽

Pathogenicity Test ◽

Conidial Suspension ◽

First Report

Blueberry (Vaccinium corymbosum) production is developing quickly in China with about 20,000 ha presently cultivated. In 2010 in Lin'an, Zhejiang Province, plants developed an apparently new disease of blueberry (cv. Duke) with symptoms consisting of wilting of foliage, stunting of plants, and reduced fruit yields. Internal vascular and cortical tissues of plant crowns showed a brown to orange discoloration. Approximately 3% of the plants in the commercial plantings were affected and eventually died after 50 to 60 days. Infected plant samples (stems and roots) collected from different fields were surface sterilized with 1.5% sodium hypochlorite for 2 min, rinsed in water, plated on 2% potato dextrose agar (PDA), and incubated at 25°C in the dark for 1 week. Single conidium cultures were consistently isolated and cultured on acidified PDA (APDA) for morphological characterization (1,2). Colonies were light with purple mycelia, and beige or orange reverse colony colors developed after 7 days incubation at 25°C. Colonies producing abundant microconidia and macroconidia. Microconidia were hyaline and oval-ellipsoid to cylindrical (3.9 to 9.6 × 1.1 to 3.4 μm). Macroconidia were 3 to 5 septate and fusoid-subulate with a pedicellate base (28.6 to 37.5 × 3.3 to 4.2 μm). Morphology and development of macroconidia and microconida were consistent with a description of Fusarium oxysporum Schltdl (1,2). The ribosomal internal transcribed spacers ITS1 and ITS2 of eight isolates were amplified using primers ITS1/ITS4 on DNA extracted from mycelium and nucleotide sequences showed 100% similarity to that of F. oxysporum. To confirm pathogenicity, 20 blueberry plants (cv. Duke) were inoculated by dipping the roots into a conidial suspension (107 conidia per ml) for 30 min. The inoculated plants were transplanted into pots containing sterilized peat and maintained at 25°C and 100% relative humidity in a growth chamber with a daily 12-h photoperiod of fluorescent light. The pathogenicity test was conducted twice. Within 40 days, all inoculated plants developed wilt symptoms similar to that observed in the field. No symptoms were observed on plants dipped into distilled water. The fungus was successfully re-isolated from crowns and roots cultured on APDA, exhibiting morphological characteristics identical to F. oxysporum (1,2), confirming Koch's postulates. To our knowledge, this is the first report of blueberry wilt caused by Fusarium. References: (1) P. M. Kirk et al. The Dictionary of the Fungi, 10th edition, page 159. CABI Bioscience, Wallingford, UK, 2008. (2) W. C. Snyder and H. N. Hansen. Am. J. Bot. 27:64, 1940.

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First report of panicle rot caused by Fusarium asiaticum on foxtail millet in China

Plant Disease ◽

10.1094/pdis-04-21-0856-pdn ◽

2021 ◽

Author(s):

Fanxin Kong ◽

Haijin Zhang ◽

Zhi Liu ◽

Guoqiu Chen ◽

Jing Xu

Keyword(s):

Foxtail Millet ◽

Morphological Characteristics ◽

Aerial Mycelium ◽

Its Region ◽

Liaoning Province ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Dark Cycle ◽

First Report ◽

Fusarium Asiaticum

Foxtail millet [ Setaria italica (L.) P. Beauv.] is one of the most important nutritious food crops. It is used for wine and health products in China. In August of 2019, panicle rot symptoms with up to 85% of panicles infected were observed on foxtail millet (cultivar Chaogu 8) in a commercial field located in Chaoyang city of Liaoning Province, China. Typical disease symptoms included brown spots on spikelets at early stages and brown-colored withering and rot of whole panicles at late stages, with the symptoms being more severe at the tip of the panicles. Under high humidity conditions, pink or salmon-colored molds developed on panicles. Symptomatic spikelet pieces were surface-disinfested with 70% ethanol for 1 min followed by 2% NaOCl for 3 min, rinsed with sterilized water for three times, and placed on potato dextrose agar (PDA) medium at 25°C. After 5 days, colonies turned pink to dark red with fluffy aerial mycelium and pigmentation with the age. Ten pure cultures were obtained from single conidia of mycelium grown on carnation leaf agar (CLA) medium at 25°C under a 12-h light-dark cycle using an inoculation needle under stereomicroscope. Macroconidia were hyaline, falcate with foot cells, 3–5 septate and size: 28.5- 44.0 μm × 3.8 - 4.9 μm. Chlamydospores were globose to subglobose (5.4 to 13.8 μm). No microconidia were produced on CLA. Black, ostiolate subglobose perithecia were formed on CLA after one month of incubation at 20°C under a 12-h light-dark cycle. Morphological characteristics of the fungus were in agreement with the description of Fusarium asiaticum (O’Donnell et al. 2004; Leslie and Summerell 2006). To validate this identification, partial translation elongation factor 1 alpha (TEF1-a) gene, and rDNA internal transcribed spacer (ITS) region of five isolates were amplified and sequenced (O’Donnell et al. 2015; White et al.1990). Identical sequences were obtained, and the sequence of one representative isolate (JGF-3) was submitted to GenBank. BLASTn analysis of both TEF sequence (MW685833) and ITS sequence (MW423687), revealed 100% sequence identity with F. asiaticum KT380120 and MT322117, respectively. Pathogenicity test were conducted on cultivar Chaogu 8 of foxtail millet. Inoculum was prepared from the culture of JGF-3 incubated in 2% mung beans juice on a shaker (140 rpm) at 25°C for 48 h. Conidial suspension (5 × 105 conidia per ml) was prepared and sprayed onto the panicles of 20 plants at the initial flowering stage and 20 additional plants that were sprayed with distilled water served as the non-inoculated controls. Treated plants were covered with plastic bags for 48 h and maintained at a greenhouse with day and night temperatures of 26 and 24°C, respectively. Two weeks after inoculation, all inoculated panicles exhibited symptoms similar to the syptoms observed in the field. No symptoms were observed in the non-inoculated control plants. The experiment was repeated twice with similar results. F. asiaticum was reisolated from the inoculated plants and its morphological characteristics matched those of the original isolates; the fungus was not reisolated from the non-inoculated plants. To our knowledge, this is the first report of F. asiaticum causing panicle rot of foxtail millet in China. To date, the disease has been observed to be present in Fuxin and Tieling city of Liaoning Province. Panicle rot can become an important disease in foxtail millet in China. References: O’Donnell, K., et al. 2004. Fungal Genetics and Biology 41: 600. Leslie, J. F., and Summerell, B. A. 2006. The Fusarium laboratory manual. Blackwell Publishing, Ames, pp 176-179. O’ Donnell, K., et al. 2015. Phytoparasitica 43: 583. White, T. J., et al. 1990. Academic Press, San Diego, CA, pp 315-322.

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First Report of Oak Anthracnose Caused by Apiognomonia errabunda on Oriental White Oak in Korea

Plant Disease ◽

10.1094/pdis-02-13-0181-pdn ◽

2013 ◽

Vol 97 (8) ◽

pp. 1121-1121

Author(s):

C. K. Lee ◽

S. H. Lee ◽

J. H. Park ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

North America ◽

Morphological Characteristics ◽

Its Region ◽

Culture Collection ◽

Deciduous Tree ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Natural Forests ◽

White Oak ◽

First Report

Oriental white oak, Quercus aliena Blume, is native to East Asia including Korea. It is one of the major deciduous tree species in natural forests in Korea. In May 2012, several hundred trees were found to be heavily damaged by a previously unknown leaf disease in a forest near Songjiho Lake in Goseong County of central Korea. Leaf symptoms began as small, water-soaked, pale greenish to grayish lesions, which enlarged to follow the veins or midribs and to be bounded by them, often killing part of the leaf. Leaf distortion and blight resulted in the later stage of disease development. A number of grayish brown to nearly black acervuli were formed on the lesions, especially on the midribs and veins. Acervuli were mostly hypophyllous, intraepidermal, erumpent, circular to ellipsoid in outline, cushion-like, and 70 to 220 μm in diameter. Conidia (n = 30) were elliptical to fusiform-elliptical, occasionally obclavate, aguttulate or guttulate, hyaline, aseptate, and 7.5 to 20 × 5 to 7.5 μm (mean 14.6 × 6.1 μm). These morphological characteristics of the fungus were consistent with the description of conidial state of Apiognomonia errabunda (Roberge ex Desm.) Höhn. (3,4). Voucher specimens were deposited in the Korea University Herbarium (KUS). An isolate obtained from KUS-F26690 was deposited in the Korean Agricultural Culture Collection (Accession No. KACC46842). Fungal DNA was extracted with DNeasy Plant Mini DNA Extraction Kits (Qiagen Inc., Valencia, CA). The complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced. The resulting 549-bp sequence was deposited in GenBank (KC426947). This showed >99% similarity with sequences of A. errabunda (AJ888475 to 888477). For pathogenicity test, inoculum was prepared by harvesting conidia from 4-week-old cultures on potato dextrose agar. A conidial suspension (1 × 106 conidia/ml) was sprayed onto young leaves of three potted seedlings. Three seedlings treated with sterile distilled water served as controls. Plants were covered with plastic bags to maintain 100% relative humidity for 24 h and then kept in a greenhouse (20 to 26°C and 60 to 80% RH). After 26 days, typical leaf spot symptoms, identical to the ones observed in the field, developed on the inoculated leaves. No symptoms were observed on controls. A. errabunda was reisolated from the lesions of inoculated plants, fulfilling Koch's postulates. Oak anthracnose associated with A. errabunda (including A. quercina) has been recorded in Europe and North America (1,4). Oak anthracnose of evergreen Quercus glauca Thunb. (syn. Cyclobalanopsis glauca (Thunb.) Oerst.) associated with A. supraseptata in Japan is not related to this disease (2). To our knowledge, this is the first report of oak anthracnose of Q. aliena globally and also the first finding of A. errabunda in Asia as well as in Korea. This pathogen is known as one of the major forest pathogens in oak stand in Europe and North America (3). Pending further studies, including a risk assessment, A. errabunda may be considered as a potentially new and serious threat in native and planted ranges of Q. aliena in Korea. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication, ARS, USDA, retrieved February 18, 2013. (2) S. Kaneko and T. Kobayashi. Trans. Mycol. Soc. Japan 25:11, 1984. (3) A. Ragazzi et al. Phytopathol. Mediterr. 46:295, 2007. (4) M. V. Sogonov et al. Mycol. Res. 111:693, 2007.

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Cinnamomum japonicum Anthracnose Caused by Colletotrichum fioriniae in Sichuan, China

Plant Disease ◽

10.1094/pdis-03-21-0635-pdn ◽

2021 ◽

Author(s):

Jie Chen ◽

Shan Han ◽

Shujiang Li ◽

Tianmin Qiao ◽

Yujue Zhou ◽

...

Keyword(s):

Disease Incidence ◽

Morphological Characteristics ◽

Aerial Mycelium ◽

Tween 80 ◽

Ribosomal Genes ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Sterile Water ◽

Colony Diameter ◽

Reference Sequences

The Cinnamomum japonicum Sieb is widely cultivated in urban in China. It’s used to make essential, lubricant, soap, and waterproof timber. In September 2019, This new leaf spot was discovered in Chengdu city (30°05′to 31°26′N, 102°54′to 104°53′E), with approximately 61.20% disease incidence. The symptoms started to occur from May to June, the worst from August to September. Firstly, the typical symptom showed round or oval, brown, and slightly sunken necrotic lesions. Gradually, the necrotic lesions increased in number, and expanded; under humid conditions the central part of the spots became black and ruptured, with orange conidial masses emerged at the margin of lesions. Finally, the leaves turn yellow and fall off. Infected tissues from ten samples were cut into small pieces 2 × 2 mm, surface sterilized for 30 s in 3% sodium hypochlorite, 60 s in 75% ethanol, rinsed three times in sterile water, placed onto potato dextrose agar (PDA) amended with streptomycin sulfate (50 μg/mL), and incubated at 25°C in a dark. Finally, 8 typical isolates exhibited the morphology described as C. fioriniae (Amelie Grammen et al. 2019). After 5 days, the colony diameter reached 28.6 to 41.2 mm and had white to light grey aerial mycelium, but was pink at the base. Orange conidia masses formed after 6-7 days, conidia were oval, slender and fusiform with acute ends (Figure 1e, f), measuring 8.3 to 19.6 × 2.9 to 7.1 μm (average: 13.9 × 4.8 μm) (Tashiro et al. 2018; Chechi et al. 2019). For molecular identification, DNA was extracted from 8 fungal colonies using a plant genomic DNA extraction kit (Solarbio, Beijing). The 5.8S nuclear ribosomal genes with the two flanking internal transcribed spacer (ITS), the glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and partial sequences of the actin (ACT), chitin synthase 1 (CHS-1), beta-tubulin (TUB2), histone3 (HIS3), calmodulin (CAL) and glutamine synthetase (GS) genes were amplified and sequenced using the primer pairs ITS1/ITS4 (White et al. 1990), GDF/GDR (Templeton et al. 1992), ACT-512F/ACT-783R, CAL 228F/CAL 737R (Carbone et al. 1999), CHS-354R/CHS-79F (Weir et al. 2012), TUB1F/Bt2bR, CYLH3F/CYLH3R (Crous et al. 2004), and GSF1/GSR1 (Liu et al. 2015), respectively. Sequences were deposited in GenBank (ITS: MT466533, GAPDH: MT460415, ACT: MT460414, CAL: MT954332, CHS-1: MT954330, TUB2: MT460416, HIS3: MT954331, and GS: MT460417). BLAST analysis showed >99.4% identity with several reference sequences of Colletotrichum fioriniae strain CBS 128517 and strain EHS58 (teleomorph of Glomerella fioriniae) previously deposited in GenBank. The conidial suspension (1 × 107 conidia/mL) collected from PDA cultures with 0.05% Tween 80 buffer was used for inoculation by spraying leaves of 5-year-old C. japonicum plants for pathogenicity test. Ten leaves of each plant (10 pots in total) were inoculated with spore suspensions (Approximately 500 μL per leaf). An equal number of control leaves were sprayed with 0.05% Tween 80 buffer to serve as a control. Twenty days later, the inoculated plants showed the similar symptoms as the original diseased plants but the controls remained asymptomatic. The C. fioriniae was re-isolated from the infected leaves and identified by morphological characteristics and DNA sequence analysis. The pathogenicity test was repeated three times with similar results, confirming Koch’s postulates. To our knowledge, this is the first report of C. japonicum anthracnose caused by C. fioriniae in China.

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First Report of Colletotrichum aenigma Causing Anthracnose of Grape in Korea

Plant Disease ◽

10.1094/pdis-11-20-2458-pdn ◽

2021 ◽

Author(s):

Ju Sung Kim ◽

Oliul Hassan ◽

Taehyun Chang

Keyword(s):

South Korea ◽

Disease Incidence ◽

Juglans Regia ◽

Morphological Characteristics ◽

Causal Agent ◽

Effective Control ◽

Pathogenicity Test ◽

Conidial Suspension ◽

First Report ◽

Colletotrichum Species

Grape (cv. Kyoho) is one of the most popular dessert fruits in South Korea. Anthracnose caused by Colletotrichum species is a common and very destructive disease of grape in the country. In 2019, severe outbreaks of anthracnose was observed in different grape orchards in Gimcheon (36º09´N, 128º00´ E), South Korea. The disease incidence on fruit was up to 50% in the orchards with most severe outbreaks and infected fruit displayed typical anthracnose symptoms including sunken necrotic lesions with orange-like conidial mass. For isolation of putative causal agents, nine diseased fruits were collected from three commercial orchards. A total of nineisolates were made from nine of the infected fruit by spreading spore masses (1x106 conidia mL-1) from each fruit on water agar and collecting single germinated spores after incubation at 25 ºC overnigh. The single germinated spores were transferred on to fresh potato dextrose agar (PDA) (Difco, Becton Dickinson) and incubated at 25ºC in the dark. Seven day old colonies were cottony white on the upper side and gray at the center on the reverse side. Conidia were cylindrical with round ends and measured 13.9 – 20.1 × 5.4 – 8.1 μm (mean = 16.5 × 6.6 μm, n = 30). Appressoria were brownish, sub-cylindrical with a few lobes and 10.3 –16.7 × 6.6 – 10.9 μm (mean = 13.1 × 8.1 μm, n = 30). The morphological characteristics of the solates resembled those of Colletotrichum species within the C. gloeosporioides complex (Weir et al. 2012). DNA was amplified using the following primer pairs: ITS1/ITS4, GDF / GDR, ACT-512F / ACT-783R, Bt2a/ Bt2b, and CHS79-F/CHS-354R (Weir et al. 2012). Accession numbers, LC586811 to LC586825 were obtained after depositing all the resulting sequences in GenBank. A 50% majority rules phylogenetic tree (Bayesian phylogenic analysis) was constructed based on concatenated sequences of ITS, GAPDH, ACT, TUB, and CHS using MrBayes 3.2.10. The present isolates formed a single clade with the reference isolates of C. aenigma (isolate ICMP 18608 and ICMP 18686). For a pathogenicity test, healthy grapefruits were collected from an orchards, surface sterilized by dipping in 1% sodium hypochlorite, rinsed with sterilized water and dried by blotting. A conidial suspension (1×106 conidia mL-1) in sterilized water were prepared from one week old colonies of isolates GRAP10 and GRAP12. A small wound was made on sterilized detached fruit by punching with a sterile pin. A drop of the conidial suspension was placed on the wound, while the control fruit received a drop of sterile water. Similarly, unwounded fruit were also inoculated with a single droplet of conidial suspension. For each isolate and method (wounded and unwounded), ten fruit were inoculated, and ten non-inoculated fruit were used as control. All the treated fruit were kept in a plastic box containing moist tissue and incubated at 25º C in the dark. Typical anthracnose lesions appeared on all inoculated wounded fruit while non-inoculated and inoculated unwounded fruits remained asymptotic. Koch postulates were fulfilled by re-isolating and re-identifying the causal agent from inoculated fruit. Colletotrichum aenigma has been reported as the causal agent of anthracnose on Juglans regia, Camellia sinensis and Actinidia arguta in China (Weir et al. 2012; Wang et al. 2016; Wang et al. 2018). Previous studies reported four Colletotrichum species (C. acutatum, C. gloeosporioides, C. fructicola, and C. viniferum) to cause this disease on grapes in South Korea (Oo and Oh 2017; Lim et al. 2020). To the best of our knowledge, this is the first report on grape anthracnose caused by C. aenigma in South Korea. This finding may help to take effective control measures of this disease.

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First Report of Leaf Spot Caused by a Phoma sp. on Schisandra chinensis in Korea

Plant Disease ◽

10.1094/pdis-05-13-0489-pdn ◽

2014 ◽

Vol 98 (1) ◽

pp. 157-157 ◽

Cited By ~ 2

Author(s):

I. Y. Choi ◽

S. E. Cho ◽

J. H. Park ◽

H. D. Shin

Keyword(s):

Leaf Spot ◽

Disease Incidence ◽

Russian Far East ◽

Morphological Characteristics ◽

Plant Diseases ◽

Leaf Spot Disease ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Schisandra Chinensis ◽

Spot Disease

Schisandra chinensis (Turcz.) Baill. is a deciduous woody vine native to northern China and the Russian Far East. Its berries have long been used in traditional Asian medicine. In Korea, S. chinensis is one of 10 major medicinal crops and, as of 2011, the production is 6,892 metric tons from 1,749 ha of cultivation area (1). During summer to autumn of 2011 and 2012, leaf spots were observed on S. chinensis (cv. Cheongsun) with disease incidence of 100% in many locations of Jangsu County, Korea. Early symptoms appeared as small, circular, and pale brown spots. Each spot increased in size, became grayish brown and necrotic, and finally developed concentric rings with a definite margin. Some spots coalesced to cover nearly half of the leaves, often becoming torn and giving a shot hole effect. The infected leaf tissue contained blackish pycnidia from which masses of conidia were released in a humid environment. The pycnidia were brown, globose to pyriform, ostiolate, and 45 to 160 μm in diameter. Conidia were hyaline, smooth, oval to ellipsoidal, aseptate or medianly 1-septate, very occasionally 2-septate, slightly constricted at the septa, 4 to 11 × 2.5 to 5 μm, and contained small oil drops. These morphological characteristics were consistent with the generic concept of Phoma (2). Three monoconidial isolates were successfully cultured by diluting conidia mass in sterile water and streaking conidia suspension on potato dextrose agar (PDA). A representative isolate was deposited in the Korean Agricultural Culture Collection (Accession No. KACC47113) and used for pathogenicity test and molecular analysis. Inoculum for a pathogenicity test was prepared by harvesting conidia from 30-day-old cultures (12-h diurnal cycle, 25°C) and a conidial suspension in water (1.1 × 107 conidia/ml) was sprayed onto leaves of three healthy seedlings (cv. Cheongsun). Three seedlings serving as controls were sprayed until runoff with sterile distilled water. The plants were separately covered with plastic bags for 48 h in a glasshouse. After 10 days, typical leaf spot symptoms developed on the leaves inoculated with the fungus. Phoma sp. was re-isolated from those lesions, confirming Koch's postulates. No symptoms were observed on controls. The pathogenicity test was conducted twice. Fungal DNA was extracted, and the complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced directly. The resulting 520-bp sequence was deposited in GenBank (Accession No. KC928322). The sequence showed over 99% similarity with many Phoma species from various substrates, but no exact matches. Phoma leaf spot of S. chinensis was once recorded in Korea without pathogenicity test and culture deposition (3). Phoma glomerata was recorded as a causal fungus of leaf spot disease on S. chinensis in China (4). The Korean isolates differ from P. glomerata in having larger conidia and are separated from it in ITS sequence data. Therefore, we tentatively place the Korean isolates as unidentified Phoma sp. To our knowledge, this is the first confirmed report of leaf spot disease caused by a Phoma sp. in Korea. References: (1) Anonymous. Statistics of Cultivation and Production of Industrial Crops in 2011. Korean Ministry for Food, Agriculture, Forestry and Fisheries. 2012. (2) M. M. Aveskamp et al. Mycologia 101:363, 2009. (3) E. J. Lee et al. Compendium of Medicinal Plant Diseases with Color Plates. Nat. Inst. Agric. Sci., Suwon, Korea. 1991. (4) X. Wang et al. Plant Dis. 96:289, 2012.

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