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

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 Corynespora Leaf Spot of Eucalyptus in China

Plant Disease ◽

10.1094/pdis-07-14-0697-pdn ◽

2015 ◽

Vol 99 (3) ◽

pp. 419-419 ◽

Cited By ~ 1

Author(s):

C. K. Phan ◽

J. G. Wei ◽

F. Liu ◽

B. S. Chen ◽

J. T. Luo ◽

...

Keyword(s):

Leaf Spot ◽

Southern China ◽

Tap Water ◽

Pathogenic Fungi ◽

Leaf Spot Disease ◽

Pathogenicity Test ◽

Commonwealth Mycological Institute ◽

Conidial Suspension ◽

Single Spore ◽

First Report

Eucalyptus is widely planted in the tropics and subtropics, and it has become an important cash crop in Southern China because of its fast-growing nature. In the Guangxi Province of southern China, Eucalyptus is produced on approximately 2 million ha, and two dominant asexual clones, Guanglin No. 9 (E. grandis × E. urophylla) and DH3229 (E. urophylla × E. grandis), are grown. Diseases are an increasing threat to Eucalyptus production in Guangxi since vast areas are monocultured with this plant. In June 2013, a leaf spot disease was observed in eight out of 14 regions in the province on a total of approximately 0.08 million ha of Eucalyptus. Initially, the lesions appeared as water-soaked dots on leaves, which then became circular or irregular shaped with central gray-brown necrotic lesions and dark red-brown margins. The size of leaf spots ranged between 1 and 3 mm in diameter. The main vein or small veins adjacent to the spots were dark. The lesions expanded rapidly during rainy days, producing reproductive structures. In severe cases, the spots coalesced and formed large irregular necrotic areas followed by defoliation. The causal fungus was isolated from diseased leaves. Briefly, the affected leaves were washed with running tap water, sterilized with 75% ethanol (30 s) and 0.1% mercuric dichloride (3 min), and then rinsed three times with sterilized water. Small segments (0.5 to 0.6 cm2) were cut from the leading edge of the lesions and plated on PDA. The plates were incubated at 25°C for 7 to 10 days. When mycelial growth and spores were observed, a single-spore culture was placed on PDA and grown in the dark at 25°C for 10 days. A pathogenicity test was done by spraying a conidial suspension (5 × 105 conidia ml–1) of isolated fungus onto 30 3-month-old leaves of Guanglin No. 9 seedlings. The plants were covered with plain plastic sheets for 7 days to keep the humidity high. Lesions similar to those observed in the forests were observed on the inoculated leaves 7 to 10 days after incubation. The same fungus was re-isolated. Leaves of control plants (sprayed with sterilized water) were disease free. Conidiophores of the fungus were straight to slightly curved, erect, unbranched, septate, and pale to light brown. Conidia were formed in chains or singly with 4 to 15 pseudosepta, which were oblong oval to cylindrical, subhyaline to pale olivaceous brown, straight to curved, 14.5 to 92.3 μm long, and 3.5 to 7.1 μm wide. The fungus was morphologically identified as Corynespora cassiicola (1). DNA of the isolate was extracted, and the internal transcribed spacer (ITS) region (which included ITS 1, 5.8S rDNA gene of rDNA, and ITS 2) was amplified with primers ITS5 and ITS4. 529 base pair (bp) of PCR product was obtained and sequenced. The sequence was compared by BLAST search to the GenBank database and showed 99% similarity to C. cassiicola (Accession No. JX087447). Our sequence was deposited into GenBank (KF669890). The biological characters of the fungus were tested. Its minimum and maximum growth temperatures on PDA were 7 and 37°C with an optimum range of 25 to 30°C. At 25°C in 100% humidity, 90% of conidia germinated after 20 h. The optimum pH for germination was 5 to 8, and the lethal temperature of conidia was 55°C. C. cassiicola has been reported causing leaf blight on Eucalyptus in India and Brazil (2,3) and causing leaf spot on Akebia trifoliate in Guangxi (4). This is the first report of this disease on Eucalyptus in China. References: (1) M. B. Ellis and P. Holliday. CMI Descriptions of Pathogenic Fungi and Bacteria, No. 303. Commonwealth Mycological Institute, Kew, Surrey, UK, 1971. (2) B. P. Reis, et al. New Dis. Rep. 29:7, 2014. (3) K. I. Wilson and L. R. Devi. Ind. Phytopathol. 19:393, 1966. (4) Y. F. Ye et al. Plant Dis. 97:1659, 2013.

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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.

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Alternaria tenuissima Causing Alternaria Blight on Pigeonpea in India

Plant Disease ◽

10.1094/pdis-01-12-0060-pdn ◽

2012 ◽

Vol 96 (6) ◽

pp. 907-907 ◽

Cited By ~ 5

Author(s):

M. Sharma ◽

R. Ghosh ◽

U. N. Mangla ◽

K. B. Saxena ◽

S. Pande

Keyword(s):

Disease Incidence ◽

Infected Plant ◽

Morphological Characteristics ◽

Severe Infection ◽

Its Region ◽

Grain Legume ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Alternaria Tenuissima ◽

Alternaria Blight

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 postharvest fruit rot on passion fruit (Passiflora edulis) caused by Lasiodiplodia theobromae in Mainland China

Plant Disease ◽

10.1094/pdis-06-20-1346-pdn ◽

2020 ◽

Author(s):

Wu Zhang ◽

Xue Li Niu ◽

Jin Yu Yang

Keyword(s):

Southern China ◽

Morphological Characteristics ◽

Its Region ◽

Passion Fruit ◽

Fruit Rot ◽

Pathogenicity Test ◽

Single Spore ◽

Passiflora Edulis ◽

Lasiodiplodia Theobromae ◽

First Report

As an economically important tropical and subtropical fruit crop, passion fruit (Passiflora edulis Sims) is widely planted in many provinces of southern China. In April 2017, postharvest fruit rot was observed on 15% to 25% of passion fruit in several fruit markets of Zhanjiang City in Guangdong Province. Initial disease symptoms on infected fruit were irregular, brown, water-soaked lesions, which enlarged into large black and sunken patches. Lesions were usually covered with an abundance of little black dots (pycnidia) and black-gray hyphae. For the pathogen isolation, fifteen symptomatic fruit were randomly collected from three local markets. Fourteen single-spore fungal isolates with similar morphology ware isolated from the infected tissues. Two isolates (ZW 49-1 and ZW 50-1) were randomly selected to further study. The colonies on PDA were initially greyish-white and became dark-gray with age. Abundant globular and irregular pycnidia were observed after incubation at 25 °C for 3 weeks. The conidia of the fungus were initially hyaline, unicellular, apex rounded, thick-walled, and ellipsoid, becoming dark brown, bicellular with longitudinal striations at maturity, 26.4 ± 2.5 × 13.4 ± 1.2 μm (n = 50). The morphology of the fungus resembled Lasiodiplodia theobromae (Pat.) Griff. & Maubl. (Phillips et al. 2013). To confirm species identification, the partial internal transcribed spacer (ITS) region of rDNA, translation elongation factor-alpha (EF1-α) and β-tubulin (TUB) gene were amplified from genomic DNA of the two isolates with the ITS1/ITS4, EF1-688F/EF1-986R, and Bt2a/Bt2b primers, respectively (Glass and Donaldson 1995; Alves et al. 2008; White et al. 1990). Base on the BLASTn analysis, the ITS (MT644473, MT644474), EF1-α (MT649210, MT649211) and TUB (MT649212, MT649213) sequences of both isolates were 100%, 99% and 100% similarity to the L. theobromae CBS 164.96 ex-type sequences in the NCBI database (AY640255, AY640258, and KU887532, respectively) (Phillips et al. 2013). For pathogenicity test, asymptomatic passion fruit were previously disinfested in 0.5 % sodium hypochlorite and superficially wounded with a sterile needle. Five-mm-diameter plugs with mycelial taken from 5-day-old PDA colonies were placed on the wounds. Sterile PDA plugs were used as negative controls. Each treatment had five replicates and the test was repeated twice. Fruit were maintained in plastic boxes to keep at 25°C for one week. One week after inoculation, gray mycelia had covered a majority of the fruit surface and caused a black, sunken rot. The inoculated fungus was reisolated and confirmed as L. theobromae by morphological characteristics. The mock inoculated fruit remained asymptomatic. The occurrence of fruit rot on passion fruit caused by L. theobromae was reported in Taiwan, China recently (Huang et al., 2019). To our knowledge, this is the first report of L. theobromae causing postharvest fruit rot on passion fruit in the Chinese mainland.

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First Report of Anthracnose Caused by Colletotrichum lupini on Yellow Lupin in Korea

Plant Disease ◽

10.1094/pdis-02-14-0175-pdn ◽

2014 ◽

Vol 98 (8) ◽

pp. 1158-1158 ◽

Cited By ~ 1

Author(s):

K. S. Han ◽

B. S. Kim ◽

I. Y. Choi ◽

J. H. Park ◽

H. D. Shin

Keyword(s):

Disease Incidence ◽

Its Region ◽

The United States ◽

Lupinus Luteus ◽

Width Ratio ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Yellow Lupin ◽

First Report ◽

Colletotrichum Lupini

Yellow lupin (Lupinus luteus L.) is native to the Mediterranean region of southern Europe. In Korea, yellow lupins are cultivated for ornamental purposes. In May 2013, hundreds of yellow lupins that were grown in pots for 7 weeks in polyethylene-film-covered greenhouses were observed severely damaged by a previously unknown disease with about 30% disease incidence in a flower farm in Yongin City, Korea. Voucher specimens were deposited in the Korea University Herbarium (KUS). Early symptoms on petioles and stems appeared as small, slightly sunken, water-soaked, and circular spots. Lesions increased in size (4 to 12 μm in diameter), became more depressed, with a darkened central portion. As the disease progressed, affected areas sometimes girdled the stem and killed the shoot. Leaves were partly blighted, but less damaged. The darkened areas contained blackish acervuli from which masses of pale salmon-colored conidia were released in moist weather. Acervuli were circular to ellipsoid, 80 to 400 μm in diameter. Acervular setae were not observed. Conidia (n = 30) were long obclavate to oblong-elliptical, aguttulate, hyaline, and 10 to 18 × 3.6 to 5.2 μm with a length/width ratio of 2.6 to 3.6. Appressoria were single or occasionally in small dense clusters, medium brown, elliptical to round in outline with a smooth to lobate margin, and 8 to 14 × 6 to 9 μm. These characters were consistent with the description of Colletotrichum lupini (Bondar) Damm, P.F. Cannon & Crous (1,3). An isolate was deposited in the Korean Agricultural Culture Collection (Accession No. KACC47254). 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 545-bp sequence was deposited in GenBank (Accession No. KJ447119). The sequence showed 100% identity with sequences of C. lupini (e.g., GenBank AJ301968, JN943480, JQ948162, and KF207599). To confirm pathogenicity, inoculum was prepared by harvesting conidia with sterile distilled water from 3-week-old cultures on potato dextrose agar. A conidial suspension (2 × 105 conidia/ml) was sprayed until runoff onto the aerial parts of five healthy plants. Control plants were sprayed with sterile water. The plants were covered with plastic bags to maintain a relative humidity of 100% for 48 h and then transferred to a greenhouse. Typical symptoms of necrotic spots appeared on the inoculated leaves 6 days after inoculation, and were identical to the ones observed in the field. C. lupini was re-isolated from symptomatic leaf tissues. No symptoms were observed on control plants. The pathogenicity test was repeated twice. Anthracnose associated with C. lupini on lupins has been known from Europe (Germany, Ukraine, Austria, and Netherlands), North America (Canada and the United States), South America (Bolivia and Brazil), and Oceania (Australia and New Zealand) (2,4). To our knowledge, this is the first report of C. lupini on yellow lupins in Asia as well as in Korea. The presence of C. lupini on lupins in Asia can be considered as a potentially new and serious threat to this ornamental plant. References: (1) U. Damm et al. Stud. Mycol. 73:37, 2012. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication, ARS, USDA, Retrieved February 17, 2014. (3) H. I. Nirenberg et al. Mycologia 94:307, 2002. (4) E. Rosskopf et al. Plant Dis. 98:161, 2014.

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First report of Colletotrichum siamense Causing Blossom Blight on Thai basil (Ocimum basilicum L.) in Malaysia

Plant Disease ◽

10.1094/pdis-06-20-1371-pdn ◽

2020 ◽

Author(s):

Siti Izera Ismail ◽

Nur Adlina Rahim ◽

Dzarifah Zulperi

Keyword(s):

Disease Incidence ◽

Its Region ◽

Ocimum Basilicum ◽

Distilled Water ◽

Single Spore ◽

First Report ◽

Plastic Bags ◽

Colletotrichum Siamense ◽

Primer Sets ◽

Acca Sellowiana

Thai basil (Ocimum basilicum L.) is widely cultivated in Malaysia and commonly used for culinary purposes. In March 2019, necrotic lesions were observed on the inflorescences of Thai basil plants with a disease incidence of 60% in Organic Edible Garden Unit, Faculty of Agriculture in the Serdang district (2°59'05.5"N 101°43'59.5"E) of Selangor province, Malaysia. Symptoms appeared as sudden, extensive brown spotting on the inflorescences of Thai basil that coalesced and rapidly expanded to cover the entire inflorescences. Diseased tissues (4×4 mm) were cut from the infected lesions, surface disinfected with 0.5% NaOCl for 1 min, rinsed three times with sterile distilled water, placed onto potato dextrose agar (PDA) plates and incubated at 25°C under 12-h photoperiod for 5 days. A total of 8 single-spore isolates were obtained from all sampled inflorescence tissues. The fungal colonies appeared white, turned grayish black with age and pale yellow on the reverse side. Conidia were one-celled, hyaline, subcylindrical with rounded end and 3 to 4 μm (width) and 13 to 15 μm (length) in size. For fungal identification to species level, genomic DNA of representative isolate (isolate C) was extracted using DNeasy Plant Mini Kit (Qiagen, USA). Internal transcribed spacer (ITS) region, calmodulin (CAL), actin (ACT), and chitin synthase-1 (CHS-1) were amplified using ITS5/ITS4 (White et al. 1990), CL1C/CL2C (Weir et al. 2012), ACT-512F/783R, and CHS-79F/CHS-345R primer sets (Carbone and Kohn 1999), respectively. A BLAST nucleotide search of ITS, CHS-1, CAL and ACT sequences showed 100% similarity to Colletotrichum siamense ex-type cultures strain C1315.2 (GenBank accession nos. ITS: JX010171 and CHS-1: JX009865) and isolate BPDI2 (CAL: FJ917505, ACT: FJ907423). The ITS, CHS-1, CAL and ACT sequences were deposited in GenBank as accession numbers MT571330, MW192791, MW192792 and MW140016. Pathogenicity was confirmed by spraying a spore suspension (1×106 spores/ml) of 7-day-old culture of isolate C onto 10 healthy inflorescences on five healthy Thai basil plants. Ten infloresences from an additional five control plants were only sprayed with sterile distilled water and the inoculated plants were covered with plastic bags for 2 days and maintained in a greenhouse at 28 ± 1°C, 98% relative humidity with a photoperiod of 12-h. Blossom blight symptoms resembling those observed in the field developed after 7 days on all inoculated inflorescences, while inflorescences on control plants remained asymptomatic. The experiment was repeated twice. C. siamense was successfully re-isolated from the infected inflorescences fulfilling Koch’s postulates. C. siamense has been reported causing blossom blight of Uraria in India (Srivastava et al. 2017), anthracnose on dragon fruit in India and fruits of Acca sellowiana in Brazil (Abirami et al. 2019; Fantinel et al. 2017). This pathogen can cause a serious threat to cultivation of Thai basil and there is currently no effective disease management strategy to control this disease. To our knowledge, this is the first report of blossom blight caused by C. siamense on Thai basil in Malaysia.

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First Report of Curvularia aeria on Etlingera linguiformis from Nagaland, India

Plant Disease ◽

10.1094/pdis-01-14-0060-pdn ◽

2014 ◽

Vol 98 (11) ◽

pp. 1580-1580 ◽

Cited By ~ 2

Author(s):

C. Kithan ◽

L. Daiho

Keyword(s):

Leaf Surface ◽

Agricultural Research ◽

Disease Incidence ◽

Indian Agricultural Research Institute ◽

Mountain Range ◽

Pathogenicity Test ◽

Distilled Water ◽

Conidial Suspension ◽

First Report ◽

Initial Symptoms

Etlingera linguiformis (Roxb.) R.M.Sm. of Zingiberaceae family is an important indigenous medicinal and aromatic plant of Nagaland, India, that grows well in warm climates with loamy soil rich in humus (1). The plant rhizome has medicinal benefits in treating sore throats, stomachache, rheumatism, and respiratory complaints, while its essential oil is used in perfumery. A severe disease incidence of leaf blight was observed on the foliar portion of E. linguiformis at the Patkai mountain range of northeast India in September 2012. Initial symptoms of the disease are small brown water soaked flecks appearing on the upper leaf surface with diameter ranging from 0.5 to 3 cm, which later coalesced to form dark brown lesions with a well-defined border. Lesions often merged to form large necrotic areas, covering more than 90% of the leaf surface, which contributed to plant death. The disease significantly reduces the number of functional leaves. As disease progresses, stems and rhizomes were also affected, reducing quality and yield. The diseased leaf tissues were surface sterilized with 0.2% sodium hypochlorite for 2 min followed by rinsing in sterile distilled water and transferred into potato dextrose agar (PDA) medium. After 3 days, the growing tips of the mycelium were transferred to PDA slants and incubated at 25 ± 2°C until conidia formation. Fungal colonies on PDA were dark gray to dark brown, usually zonate; stromata regularly and abundantly formed in culture. Conidia were straight to curved, ellipsoidal, 3-septate, rarely 4-septate, middle cells broad and darker than other two end cells, middle septum not median, smooth, 18 to 32 × 8 to 16 μm (mean 25.15 × 12.10 μm). Conidiophores were terminal and lateral on hyphae and stromata, simple or branched, straight or flexuous, often geniculate, septate, pale brown to brown, smooth, and up to 800 μm thick (2,3). Pathogen identification was performed by the Indian Type Culture Collection, Division of Plant Pathology, Indian Agricultural Research Institute, New Delhi (ITCC Accession No. 7895.10). Further molecular identity of the pathogen was confirmed as Curvularia aeria by PCR amplification and sequencing of the internal transcribed spacer (ITS) regions of the ribosomal DNA by using primers ITS4 and ITS5 (4). The sequence was submitted to GenBank (Accession No. MTCC11875). BLAST analysis of the fungal sequence showed 100% nucleotide similarity with Cochliobolus lunatus and Curvularia aeria. Pathogenicity tests were performed by spraying with an aqueous conidial suspension (1 × 106 conidia /ml) on leaves of three healthy Etlingera plants. Three plants sprayed with sterile distilled water served as controls. The first foliar lesions developed on leaves 7 days after inoculation and after 10 to 12 days, 80% of the leaves were severely infected. Control plants remained healthy. The inoculated leaves developed similar blight symptoms to those observed on naturally infected leaves. C. aeria was re-isolated from the inoculated leaves, thus fulfilling Koch's postulates. The pathogenicity test was repeated twice. To our knowledge, this is the first report of the presence of C. aeria on E. linguiformis. References: (1) M. H. Arafat et al. Pharm. J. 16:33, 2013. (2) M. B. Ellis. Dematiaceous Hyphomycetes. CMI, Kew, Surrey, UK, 1971. (3) K. J. Martin and P. T. Rygiewicz. BMC Microbiol. 5:28, 2005. (4) C. V. Suberamanian. Proc. Indian Acad. Sci. 38:27, 1955.

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First Report of Ramularia coleosporii causing Leaf Spot on Perilla frutescens in Korea

Plant Disease ◽

10.1094/pdis-01-21-0223-pdn ◽

2021 ◽

Author(s):

Md Aktaruzzaman ◽

Tania Afroz ◽

Hyo-Won Choi ◽

Byung Sup Kim

Keyword(s):

Leaf Spot ◽

Ipomoea Batatas ◽

Rust Fungus ◽

Morphological Characteristics ◽

Perilla Frutescens ◽

Herbaceous Plant ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Single Spore ◽

First Report

Perilla (Perilla frutescens var. japonica), a member of the family Labiatae, is an annual herbaceous plant native to Asia. Its fresh leaves are directly consumed and its seeds are used for cooking oil. In July 2018, leaf spots symptoms were observed in an experimental field at Gangneung-Wonju National University, Gangneung, Gangwon province, Korea. Approximately 30% of the perilla plants growing in an area of about 0.1 ha were affected. Small, circular to oval, necrotic spots with yellow borders were scattered across upper leaves. Masses of white spores were observed on the leaf underside. Ten small pieces of tissue were removed from the lesion margins of the lesions, surface disinfected with NaOCl (1% v/v) for 30 s, and then rinsed three times with distilled water for 60 s. The tissue pieces were then placed on potato dextrose agar (PDA) and incubated at 25°C for 7 days. Five single spore isolates were obtained and cultured on PDA. The fungus was slow-growing and produced 30-50 mm diameter, whitish colonies on PDA when incubated at 25ºC for 15 days. Conidia (n= 50) ranged from 5.5 to 21.3 × 3.5 to 5.8 μm, were catenate, in simple or branched chains, ellipsoid-ovoid, fusiform, and old conidia sometimes had 1 to 3 conspicuous hila. Conidiophores (n= 10) were 21.3 to 125.8 × 1.3 to 3.6 μm in size, unbranched, straight or flexuous, and hyaline. The morphological characteristics of five isolates were similar. Morphological characteristics were consistent with those described for Ramularia coleosporii (Braun, 1998). Two representative isolates (PLS 001 & PLS003) were deposited in the Korean Agricultural Culture Collection (KACC48670 & KACC 48671). For molecular identification, a multi-locus sequence analysis was conducted. The internal transcribed spacer (ITS) regions of the rDNA, partial actin (ACT) gene and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene were amplified using primer sets ITS1/4, ACT-512F/ACT-783R and gpd1/gpd2, respectively (Videira et al. 2016). Sequences obtained from each of the three loci for isolate PLS001 and PLS003 were deposited in GenBank with accession numbers MH974744, MW470869 (ITS); MW470867, MW470870 (ACT); and MW470868, MW470871 (GAPDH), respectively. Sequences for all three genes exhibited 100% identity with R. coleosporii, GenBank accession nos. GU214692 (ITS), KX287643 (ACT), and 288200 (GAPDH) for both isolates. A multi-locus phylogenetic tree, constructed by the neighbor-joining method with closely related reference sequences downloaded from the GenBank database and these two isolates demonstrated alignment with R. coleosporii. To confirm pathogenicity, 150 mL of a conidial suspension (2 × 105 spores per mL) was sprayed on five, 45 days old perilla plants. An additional five plants, to serve as controls, were sprayed with sterile water. All plants were placed in a humidity chamber (>90% relative humidity) at 25°C for 48 h after inoculation and then placed in a greenhouse at 22/28°C (night/day). After 15 days leaf spot symptoms, similar to the original symptoms, developed on the leaves of the inoculated plants, whereas the control plants remained symptomless. The pathogenicity test was repeated twice with similar results. A fungus was re-isolated from the leaf lesions on the inoculated plants which exhibited the same morphological characteristics as the original isolates, fulfilling Koch’s postulates. R. coleosporii has been reported as a hyperparasite on the rust fungus Coleosporium plumeriae in India & Thailand and also as a pathogen infecting leaves of Campanula rapunculoides in Armenia, Clematis gouriana in Taiwan, Ipomoea batatas in Puerto Rico, and Perilla frutescens var. acuta in China (Baiswar et al. 2015; Farr and Rossman 2021). To the best of our knowledge, this is the first report of R. coleosporii causing leaf spot on P. frutescens var. japonica in Korea. This disease poses a threat to production and management strategies to minimize leaf spot should be developed.

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First Report of Colletotrichum boninense Causing Anthracnose on Pepper in China

Plant Disease ◽

10.1094/pdis-04-12-0403-pdn ◽

2013 ◽

Vol 97 (1) ◽

pp. 138-138 ◽

Cited By ~ 7

Author(s):

Y. Z. Diao ◽

J. R. Fan ◽

Z. W. Wang ◽

X. L. Liu

Keyword(s):

Internal Transcribed Spacer ◽

Severe Disease ◽

Causal Agent ◽

Its Sequences ◽

Universal Primers ◽

Pathogenicity Test ◽

Conidial Suspension ◽

Single Spore ◽

First Report ◽

Species Specific

Anthracnose, caused by Colletotrichum spp., is a severe disease and results in large losses in pepper (Capsicum frutescens) production in China (4). Colletotrichum boninense is one of the Colletotrichum species in pepper in China. In August 2011, anthracnose symptoms (circular, sunken lesions with orange to black spore masses) were observed on pepper fruits in De-Yang, Sichuan Province, China. Three single-spore isolates (SC-6-1, SC-6-2, SC-6-3) were obtained from the infected fruits. A 5-mm diameter plug was transferred to potato dextrose agar (PDA); the isolates formed colonies with white margins and circular, dull orange centers. The conidia were cylindrical, obtuse at both ends, and 10.5 to 12.6 × 4.1 to 5.0 μm. The colonies grew rapidly at 25 to 28°C, and the average colony diameter was 51 to 52 mm after 5 days on PDA at 25°C. Based upon these characters, the causal agent was identified as C. boninense. To confirm the identity of the isolates, the internal transcribed spacer (ITS) regions were amplified with the ITS1/ITS4 universal primers (1). The internal transcribed spacer (ITS) sequences (Accession No. JQ926743) of the causal fungus shared 99 to 100% homology with ITS sequences of C. boninense in GenBank (Accession Nos. FN566865 and EU822801). The identity of the causal agent as C. boninense was also confirmed by species-specific primers (Col1/ITS4) (2). In a pathogenicity test, five detached ripe pepper fruits were inoculated with 1 μl of a conidial suspension (106 conidia/mL) or five fruits with 1 μl of sterile water were kept as control. After 7 days in a moist chamber at 25°C, typical anthracnose symptoms had developed on the five inoculated fruits but not on control fruits. C. boninense was reisolated from the lesions, and which was confirmed by morphology and molecular methods as before. There have reports of C. boninense infecting many species of plants, including pepper (3). To our knowledge, this is the first report of C. boninense causing anthracnose on pepper in China. References: (1) A. K. Lucia et al. Phytopathology 93:581, 2002. (2) S. A. Pileggi et al. Can. J. Microbiol. 55:1081, 2009. (3) H. J. Tozze et al. Plant Dis. 93:106, 2009. (4) M. L. Zhang. J. Anhui Agri. Sci. 2:21, 2000.

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