First Report of Ergot of Bermudagrass Caused by Claviceps cynodontis in Oklahoma

During late June and early July of 2005, signs of bermudagrass ergot were reported from numerous northern and eastern counties in Oklahoma. Signs were observed primarily on forage-type bermudagrass (Cynodon dactylon (L.) Pers.), as well as bermudagrass turf. During the “honeydew” stage, honeydew was frequently observed exuding from most of the ovaries of infected inflorescences. These signs of ergot have been observed previously on bermudagrass in Oklahoma and Texas (1). Sphacelia-type conidia were abundantly produced during the honeydew stage and were single-celled, hyaline, averaged 14 × 5 μm in size, and were reniform to allantoid in shape. When streaked on water agar, conidia produced terminal holoblastic secondary conidia. Single-spore cultures were isolated from the honeydew of bermudagrasses from Logan and Muskogee counties in Oklahoma and grew slowly as white mycelium on potato dextrose agar (PDA). Koch's postulates were fulfilled for these two isolates by spray inoculating four bermudagrass inflorescences at anthesis with mycelium scraped from a PDA plate and homogenized in water. Control plants' inflorescences were sprayed with a water suspension of a similar amount of sterile PDA as inoculated plants. Plants were placed inside plastic bags to maintain humidity and incubated in a growth chamber at 22°C (14-h photoperiod) and 20°C (10 h of darkness). After 9 days, honeydew exuded from the inoculated inflorescences, but not from the controls. Single-spore cultures were reisolated from the honeydew, and conidia streaked on water agar formed identical secondary conidia. The complete nuclear ribosomal internal transcribed spacer (ITS) region was amplified from DNA extracted from honeydew and single-spore cultures using the ITS4 and ITS5 primers (4) and sequenced. All sequences were identical and a search of GenBank at NCBI found these sequences were most similar to the ITS regions of Claviceps cynodontis Langdon (100%, Accession No. AJ557074) and C. maximensis Theis (99%, Accession No. AJ133396). The ITS sequence from the Logan County isolate was deposited at Gen-Bank (Accession DQ187312). The morphology, secondary conidiation, and ITS sequences identify the causal fungus as C. cynodontis (2) and differentiate it from C. purpurea (Fr.) Tul., the previously identified cause of bermudagrass ergot (1). To our knowledge, this is the first report of C. cynodontis on bermudagrass in Oklahoma and may represent a recent introduction to the United States (2; S. Pažoutová and M. Flieger, personal communication). A Claviceps sp. isolated from bermudagrass has been shown to produce ergot alkaloids possibly causing “bermudagrass tremors” in cattle (3). In regions where bermudagrass is the predominant forage for livestock, the toxicological significance of bermudagrass ergot caused by C. cynodontis is unclear and requires further research. References: (1) K. E. Conway et al. Plant Dis. 76:1077, 1992. (2) S. Pažoutová et al. Can J. Plant Pathol. 27:541, 2005. (3) J. K. Porter et al. J. Agric. Food Chem. 22:838, 1974. (4) T. J. White et al. Pages 315–322 in: PCR Protocols: A Guide to Methods and Applications. Academic Press Inc., New York, 1990.

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First Report of Leaf Spot Caused by Phyllosticta yuccae on Yucca filamentosa in Brazil

Plant Disease ◽

10.1094/pdis-04-13-0384-pdn ◽

2013 ◽

Vol 97 (9) ◽

pp. 1257-1257 ◽

Cited By ~ 1

Author(s):

A. D. A. Silva ◽

D. B. Pinho ◽

B. T. Hora Junior ◽

O. L. Pereira

Keyword(s):

Leaf Spot ◽

Its Region ◽

The United States ◽

Leaf Spot Disease ◽

Infected Leaf ◽

Single Spore ◽

First Report ◽

Leaf Spots ◽

Slime Layer ◽

Pure Cultures

Yucca filamentosa L. (Agavaceae), commonly known as Adam's needle, is known in Brazil as “agulha-de-adão.” It is an ornamental garden plant with medicinal properties (4). In 2010, 100% of Y. filamentosa seedlings and plants were observed with a severe leaf spot disease in two ornamental nurseries located in the municipality of Viçosa, Minas Gerais, Brazil. Initially, lesions were dark brown, elliptical, and scattered, and later became grayish at the center with a reddish brown margin, irregular and coalescent. Infected leaf samples were deposited in the herbarium at the Universidade Federal de Viçosa (Accession Nos. VIC32054 and VIC32055). A fungus was isolated from the leaf spots and single-spore pure cultures were obtained on potato dextrose agar (PDA). The sporulating single-spore cultures were deposited at the Coleção de Culturas de Fungos Fitopatogênicos “Prof. Maria Menezes” (CMM 1843 and CMM 1844). On the leaf, the fungus produced pycnidial conidiomata that were scattered or gregarious, usually epiphyllous, immersed, dark brown, unilocular, subglobose, and 95 to 158 × 108 to 175 μm, with a minute, subcircular ostiole. Conidiogenous cells were blastic, hyaline, conoidal, or short cylindrical. Conidia were aseptate, hyaline, smooth walled, coarsely granular, broadly ellipsoidal to subglobose or obovate, usually broadly rounded at both ends, occasionally truncate at the base or indented slightly at the apex, and 7.5 to 13.5 × 6 to 10 μm. Conidia were also surrounded by a slime layer, usually with a hyaline, flexuous, narrowly conoidal or cylindrical, mucilaginous apical appendage that was 10 to 16 μm long. Spermatia were hyaline, dumbbell shaped to cylindrical, both ends bluntly rounded, and 3 to 5 × 1 to 1.5 μm. These characteristics matched well with the description of Phyllosticta yuccae Bissett (1). To confirm this identification, DNA was extracted using a Wizard Genomic DNA Purification Kit and amplified using primers ITS1 and ITS4 (2) for the ITS region (GenBank Accession Nos. JX227945 and JX227946) and EF1-F and EF2-R (3) for the TEF-1α (JX227947 and JX227948). The sequencing was performed by Macrogen, South Korea. The ITS sequence matched sequence No. JN692541, P. yuccae, with 100% identity. To confirm Koch's postulates, four leaves of Y. filamentosa (five plants) were inoculated with 6-mm-diameter plugs from a 7-day-old culture growing on PDA. The leaves were covered with plastic sack and plants were maintained at 25°C. In a similar manner, fungus-free PDA plugs were placed on five control plants. Symptoms were consistently similar to those initially observed in the nurseries and all plants developed leaf spots by 15 days after inoculation. P. yuccae was successfully reisolated from the symptomatic tissue and control plants remained symptomless. P. yuccae has been previously reported in Canada, the Dominican Republic, Guatemala, Iran, and the United States of America. To our knowledge, this is the first report of P. yuccae causing disease in Y. filamentosa in Brazil and it may become a serious problem for the nurseries, due to the severity of the disease and the lack of chemical products to control this pathogen. References: (1) J. Bissett. Can. J. Bot. 64:1720, 1986. (2) M. A. Innis et al. PCR Protocols: A guide to methods and applications. Academic Press, 1990. (3) Jacobs et al. Mycol. Res. 108:411, 2004. (4) H. Lorenzi and H. M. Souza. Plantas Ornamentais no Brasil. Instituto Plantarum, 2001.

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First Report of Gliocephalotrichum bulbilium Causing Fruit Rot of Posthavest Mangosteen in China

Plant Disease ◽

10.1094/pdis-09-13-0917-pdn ◽

2014 ◽

Vol 98 (7) ◽

pp. 994-994 ◽

Cited By ~ 1

Author(s):

Y. X. Li ◽

W. X. Chen ◽

A. Y. Liu ◽

Q. L. Chen ◽

S. J. Feng

Keyword(s):

Its Region ◽

The United States ◽

Psidium Guajava ◽

Morphological Characters ◽

Fruit Rot ◽

Diseased Plant ◽

Garcinia Mangostana ◽

Single Spore ◽

Tropical Fruit ◽

First Report

Mangosteen (Garcinia mangostana L., Guttiferae) is a tropical fruit renowned for its pleasant taste, rich nutrition, and medicinal value. Little research about mangosteen diseases during storage and transport has been reported. In June of 2012, fruit rots on mangosteens imported from Thailand were observed in Guangzhou, China. In infected fruits, pericarps showed an increased firmness, were discolored to deep pink, and the edible aril became brown and rotten. In order to search for the etiological agent of this rot symptom, infected mangosteens were analyzed. Diseased mangosteen tissues were surface-sterilized with 70% alcohol, then with 0.1% HgCl2, dipped in sterilized water three times, and placed onto potato dextrose agar (PDA) at 26°C. The fungi isolated from tissues of the pericarp and aril were similar in morphology and grew rapidly, covering the plate surface (9 mm diameter) after 2 to 3 days of incubation at 26°C. The morphological characters of 10 single-spore isolates were observed. These isolates showed light yellow to light brown fertile colonies on PDA. On corn meal agar (CMA), conidiophores were erect, arising from wide hyphae; they were composed of a basal stipe ending in a penicillate conidiogenous apparatus with directly subtending sterile stipe extensions ranging from 74.5 to 195.0 μm long. Conidia were unicellular, smooth, oblong to elliptical, 6.3 to 8.5 × 2.5 to 3.0 μm, and accumulated in a mucilaginous mass. Chlamydospores were multicellular, dark brown, regular in shape and thick-walled, and 40.0 to 52.5 μm in diameter. On the basis of these morphological characters, these isolates were identified as Gliocephalotrichum bulbilium (2). To confirm the identity of this fungus, genomic DNA of two isolates was extracted, and fragments of ITS region and β-tubulin gene were amplified by PCR, sequenced, and compared with sequences of Gliocephalotrichum species available in NCBI GenBank. Both DNA regions (GenBank Accession Nos. KF716166 and KF716168) had sequence similarities of 99% and 97%, respectively, to other G. bulbilium sequences at GenBank. Pathogenicity tests were conducted on three detached fruits for two isolates. Fruits were inoculated using 5-mm mycelial disks with conidia taken from 3-day-old cultures of G. bulbilium isolate Gb1 and Gb10 grown on PDA. Controls were inoculated with PDA disks only. All treated fruits were kept individually in a humid chamber at 26°C. Tests were repeated twice. Three days after inoculation, white mycelial growth for Gb was observed at inoculation sites. Eight days after inoculation, mycelium of Gb nearly covered the fruit, causing fruit rot, and the pericarp became hard and light in color. The control fruit did not rot. G. bulbilium was re-isolated from diseased plant tissue, thus fulfilling Koch's postulates. G. bulbilium has been reported causing postharvest fruit rot of rambutan (Nephelium lappaceum) and guava (Psidium guajava) in some locations (3,4). Moreover, the fungus caused cranberry fruit rot in the United States (1). To our knowledge, this is the first report of G. bulbilium causing postharvest fruit rot of mangosteen in China. It is uncertain whether the fungus infected mangosteen in Thailand and was carried to China due to commercial relationship. References: (1) C. Constantelos et al. Plant Dis. 95:618, 2011. (2) C. Decock et al. Mycologia 98:488, 2006. (3) L. M. Serrato-Diaz et al. Plant Dis. 96:1225, 2012. (4) A. Sivapalan et al. Australas. Plant Pathol. 27:274, 1998.

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First Report of Rhizoctonia solani AG2-2IIIB Infecting Potato Stems and Stolons in the United States

Plant Disease ◽

10.1094/pdis-10-11-0899 ◽

2012 ◽

Vol 96 (3) ◽

pp. 460-460 ◽

Cited By ~ 3

Author(s):

J. W. Woodhall ◽

A. R. Belcher ◽

J. C. Peters ◽

W. W. Kirk ◽

P. S. Wharton

Keyword(s):

United States ◽

New York ◽

Sugar Beet ◽

Rhizoctonia Solani ◽

Its Region ◽

Stem Canker ◽

The United States ◽

Potato Disease ◽

First Report ◽

Plant Pathol

Rhizoctonia solani is an important pathogen of potato (Solanum tuberosum) causing qualitative and quantitative losses. It has been associated with black scurf and stem canker. Isolates of the fungus are assigned to one of 13 known anastomosis groups (AGs), of which AG3 is most commonly associated with potato disease (2,4). In August 2011, diseased potato plants originating from Rupert, ID (cv. Western Russet) and Three Rivers, MI (cv. Russet Norkotah) were received for diagnosis. Both samples displayed stem and stolon lesions typically associated with Rhizoctonia stem canker. The presence of R. solani was confirmed through isolation as previously described (4) and the Idaho and Michigan isolates were designated J11 and J8, respectively. AG was determined by sequencing the rDNA internal transcribed spacer (ITS) region using primers ITS5 and ITS4 (3). The resulting sequences of the rDNA ITS region of isolates J8 and J11 (GenBank Accession Nos. HE608839 and HE608840, respectively) were between 97 and 100% identical to that of other AG2-2IIIB isolates present in sequence databases (GenBank Accession Nos. FJ492075 and FJ492170, respectively). Koch's postulates were confirmed for each isolate by carrying out the following protocol. Each isolate was cultured on potato dextrose agar for 14 days. Five 10-mm agar plugs were then placed on top of seed tubers (cv. Maris Piper) in 1-liter pots containing John Innes Number 3 compost (John Innes Manufacturers Association, Reading, UK). Pots were held in a controlled environment room at 18°C with 50% relative humidity and watered as required. After 21 days, plants were removed and assessed for disease. Typical Rhizoctonia stem lesions were observed and R. solani was successfully reisolated from symptomatic material. To our knowledge, this is the first report of AG2-2IIIB causing disease on potatoes in the United States. In the United States, AGs 2-1, 3, 4, 5, and 9 have all been previously implicated in Rhizoctonia potato disease (2). AG2-2IIIB should now also be considered a potato pathogen in the United States. Knowledge of which AG is present is invaluable when considering a disease management strategy. AG2-2IIIB is a causal agent of sugar beet (Beta vulgaris) root rot in Idaho (1). Sugar beet is commonly grown in crop rotation with potato and such a rotation could increase the risk of soilborne infection to either crop by AG2-2IIIB. References: (1) C. A. Strausbaugh et al. Can. J. Plant Pathol. 33:210, 2011. (2) L. Tsror. J. Phytopatol. 158:649, 2010. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, Inc., New York, 1990. (4) J. W.Woodhall et al. Plant Pathol. 56:286, 2007.

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First Report of Colletotrichum coccodes Causing Leaf and Neck Anthracnose on Onions (Allium cepa) in Michigan and the United States

Plant Disease ◽

10.1094/pdis-01-12-0022-pdn ◽

2012 ◽

Vol 96 (5) ◽

pp. 769-769 ◽

Cited By ~ 2

Author(s):

L. M. Rodriguez-Salamanca ◽

T. B. Enzenbacher ◽

M. L. Derie ◽

L. J. du Toit ◽

C. Feng ◽

...

Keyword(s):

Its Region ◽

The United States ◽

Distilled Water ◽

Conidial Suspension ◽

Water Control ◽

First Report ◽

Plastic Bags ◽

Pathogenicity Tests ◽

Colletotrichum Spp ◽

Water Plants

In July of 2010, dry, oval lesions, each with a salmon-colored center and bleached overall appearance, were observed on the leaves and neck of onions plants growing in production fields of Newaygo, Ottawa, Kent, and Ionia counties, Michigan. Acervuli and setae that are characteristic of Colletotrichum spp. were observed with a dissecting microscope, and elliptical conidia (8 to 23 × 3 to 12 μm) with attenuated ends were observed with a compound microscope. Symptomatic tissues were excised and cultured onto potato dextrose agar amended with 30 and 100 ppm of rifampicin and ampicillin, respectively. The cultures produced pale salmon-colored sporulation after growing for 5 days at 22 ± 2°C and black microsclerotia after 2 weeks. Six isolates were confirmed as C. coccodes based on sequence analysis of the internal transcribed (ITS) region of the ribosomal DNA and a 1-kb intron of the glutamine synthase gene (GS) (2). Sequences were submitted to GenBank (Accession Nos. JQ682644 and JQ682645 for ITS and GS, respectively). Pathogenicity tests were conducted on two- to three-leaved ‘Stanley’ and ‘Cortland’ onion seedlings. Prior to inoculation, seedlings were enclosed in clear plastic bags overnight to provide high relative humidity. The bags were removed, and seedlings were sprayed inoculated with a C. coccodes conidial suspension (5 × 105 conidia/ml and 25 ml/plant) in sterile double-distilled water. Control seedlings were sprayed with sterile double-distilled water. Tween (0.01%) was added to the conidial suspension and the water. Plants were enclosed in bags for 72 h postinoculation and incubated in growth chambers at 28°C day/23°C night with a 12-h photoperiod. Sunken, oval lesions were observed on the foliage of the onion seedlings inoculated with C. coccodes 4 days postinoculation. Lesions coalesced and foliage collapsed 7 days postinoculation. Control plants remained asymptomatic. When five leaf samples per replication were detached and incubated in a moist chamber for 3 days at 21 ± 2°C, abundant acervuli and setae were observed on the symptomatic tissue but not on control tissue. C. coccodes was consistently recovered from the onion seedling lesions. Six different Colletotrichum spp. have been reported to cause diseases on onions worldwide (1,4). C. circinans, which causes smudge, is an occasional onion pathogen in Michigan, while C. gloeosporioides has only been reported to be infecting onions in Georgia (3). To our knowledge, this is the first report of C. coccodes infecting and causing disease in onions plants. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , August 6, 2010. (2) J. C. Guerber et al. Mycologia 95:872. 2003. (3) C. Nischwitz et al. Plant Dis. 92:974. 2008. (4) H. F. Schwartz, and K. S. Mohan. Compendium of Onion and Garlic Diseases and Pests, 2nd ed. The American Phytopathological Society, St. Paul, MN. 1995.

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First Report of Black Rot of Carrots Caused by Alternaria radicina in Michigan

Plant Disease ◽

10.1094/pd-90-0684b ◽

2006 ◽

Vol 90 (5) ◽

pp. 684-684

Author(s):

C. Saude ◽

M. K. Hausbeck

Keyword(s):

United States ◽

New York ◽

Sequence Similarity ◽

Morphological Characteristics ◽

Its Region ◽

The United States ◽

Distilled Water ◽

First Report ◽

Plastic Bags ◽

Alternaria Sp

In April 2005, an Alternaria sp. was isolated from carrot (Daucus carota) roots harvested in the fall of 2004 and held at 1 to 3°C in a storage facility in Newaygo County, MI. The pathogen was readily isolated on water agar from root tissue exhibiting grayish black, sunken lesions. Morphological characteristics were noted 5 to 7 days after single-conidium cultures were established on potato dextrose agar (3). Sixteen Alternaria sp. isolates were recovered. Cultures were dark olive brown, and conidia were pigmented, ellipsoidal, and produced singly or in chains of two. Conidia were 35 to 45 μm long and 15 to18 μm in diameter, usually with three to eight transverse and one to four longitudinal septa. Pathogenicity of isolates was tested on carrot roots in the laboratory and carrot seedlings (cv. Goliath) in the greenhouse. In the laboratory, four surface-sterilized, whole carrot roots were sprayed until runoff with 2 × 106 conidia/ml of each isolate and incubated at 23 to 25°C in a moist chamber for 10 days. Controls were sprayed with sterile distilled water. Ten to fifteen days after inoculation, inoculated carrots exhibited grayish black, sunken lesions, and an Alternaria sp. was reisolated from the margin of the lesions. Controls remained healthy. In the greenhouse, seven pots containing one 2-week-old carrot seedling were watered to saturation and plants were sprayed until runoff with 2 × 106 conidia/ml for each isolate. Control plants were sprayed with sterile distilled water. After inoculation, plants were enclosed in clear plastic bags, placed under 63% woven shade cloth and watered regularly. Black lesions were observed on the foliage 7 days after inoculation, and wilt and death of plants were observed 15 to 30 days after inoculation. Alternaria sp. was reisolated from the foliage of symptomatic plants. Control plants remained healthy. DNA was extracted from all isolates, and the nuclear ribosomal internal transcribed spacer (ITS) region amplified with primers ITS4 and ITS5 and sequenced. A portion of the ITS sequence has been deposited in the NCBI database (GenBank Accession No. DQ394073). A BLAST search of the NCBI database with the ITS sequences revealed A. radicina, Accession No AY154704, as the closest match with 100% sequence similarity. In September 2005, an Alternaria sp. was isolated from black lesions on carrot roots, crowns, and foliage that were collected from fields in Newaygo and Oceana counties, MI. The recovered isolates were morphologically similar to A. radicina isolates obtained from stored carrots in April 2005. First isolated and identified on stored carrots in New York (3), A. radicina is also present in other carrot-producing areas of the United States (1) and was isolated not only from stored carrots but also from carrots in the field (2) and carrot seeds (4). To our knowledge, this is the first report of A. radicina on stored and field carrots in Michigan, which signifies a serious risk to a carrot industry that ranks among the top five in the United States. References: (1) D. F. Farr et al. Fungi on Plants and Plant Produce in the United States.The American Phytopathological Society, St. Paul, MN, 1989. (2) R. G. Grogan and W. C. Snyder. Phytopathology 42:215, 1952. (3) F. C. Meier and E. D. Eddy. Phytopathology 12:157, 1922. (4) B. M. Pryor and R. L. Gilbertson. Plant Dis. 85:18, 2001.

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First Report of Rhizoctonia solani AG-1-IB Causing Leaf Blight of Sorrel (Rumex acetosa) in Brazil

Plant Disease ◽

10.1094/pdis-04-13-0443-pdn ◽

2014 ◽

Vol 98 (2) ◽

pp. 278-278

Author(s):

B. E. C. Miranda ◽

A. M. S. Cardoso ◽

R. W. Barreto

Keyword(s):

New York ◽

Rhizoctonia Solani ◽

Its Region ◽

The United States ◽

Anastomosis Group ◽

Culture Collection ◽

Representative Specimen ◽

Broad Host Range ◽

Rumex Acetosa ◽

First Report

Rumex acetosa L., common name sorrel (in Brazil, azedinha), is an herb from Europe and Asia commonly used either as a vegetable or a medicinal plant (1). No pathogen has been recorded on this plant species in Brazil, where it has been promoted as an alternative vegetable crop. During a routine inspection of a vegetable garden in the campus of the Universidade Federal de Viçosa (Viçosa, state of Minas Gerais, Brazil) in July 2011, a group of sorrel plants were found bearing blight symptoms. Infected leaves had laminae with soaked irregular necrotic areas and infected petioles had reddish lesions. Healthy leaves touched by neighboring blighted leaves became diseased. A mycelial web was always associated with necrotic tissues. A representative specimen was collected, dried in a plant press, and deposited in the local herbarium (VIC 39063). Pure cultures were obtained through direct transfer of mycelium to PDA plates and deposited in the culture collection at the Universidade Federal de Viçosa – Coleção Oswaldo Almeida Drummond (COAD 1265). Slides containing fungal structures were mounted in lactophenol and observed under a microscope (Olympus BX 51). The fungus had the following morphology: mycelium superficial, either filiform or monilioid and constricted at septae, 6 to 10 μm diameter, often branching at right angles or nearly so, typically bearing a septum at branches near the branching point. Additionally, large, poorly differentiated, dirty white sclerotia were formed in older cultures. When mounted in DAPI, 7-day-old mycelium was seen to bear 5 to 13 nuclei per cell. These characteristics suggested that the fungus was Rhizoctonia solani Kuhn (RS). Anastomosis group (AG) was determined by sequencing the rDNA internal transcribed spacer (ITS) region using primers ITS5 and ITS4 (4). A BLAST search revealed that the sequence (GenBank Accession No. KC887353) had 96% sequence identity with RS AG-1-IB GenBank accessions JN426850.1, GU596491.1, JQ692292.1, and JQ692291.1. Pathogenicity of the isolate obtained from sorrel was tested by inoculating four healthy individuals with culture plugs taken from the margin of actively growing cultures on V8 juice agar. Inoculated plants were placed in a dew chamber for 48 h and later transferred to the bench of a greenhouse. Necrosis appeared on all inoculated plants 2 days after inoculation, developing into severe blight after 7 days. RS was isolated from infected tissues. RS AG-1-IB is known as a broad host-range plant pathogen (3). This is its first report as a pathogen of sorrel in Brazil. The sole other published record of this disease on sorrel is from the United States (2). References: (1) N. R. Madeira et al. Hortic. Brasil. 26:428, 2008. (2) G. L. Peltier. Parasitic rhizoctonias in America. University of Illinois Agricultural Experiment Station, 1915. (3) B. Sneh, L. Burpee, and A. Ogoshi. Identification of Rhizoctonia species. APS Press, St Paul, MN, 1991. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, Inc., New York, 1990.

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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 Leaf Blight and Stem Canker of Pachysandra terminalis Caused by Pseudonectria pachysandricola in Korea

Plant Disease ◽

10.1094/pdis-09-11-0813 ◽

2012 ◽

Vol 96 (2) ◽

pp. 287-287

Author(s):

K. S. Han ◽

J. H. Park ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

United States ◽

Its Region ◽

Stem Canker ◽

The United States ◽

Culture Collection ◽

Leaf Blight ◽

First Report ◽

Cornell University ◽

Plastic Bags ◽

Young Leaves

Pachysandra terminalis Siebold & Zucc., known as Japanese pachysandra, is a creeping evergreen perennial belonging to the family Buxaceae. In April 2011, hundreds of plants showing symptoms of leaf blight and stem canker with nearly 100% incidence were found in a private garden in Suwon, Korea. Plants with the same symptoms were found in Seoul in May and Hongcheon in August. Affected leaves contained tan-to-yellow brown blotches. Stem and stolon cankers first appeared as water soaked and developed into necrotic lesions. Sporodochia were solitary, erumpent, circular, 50 to 150 μm in diameter, salmon-colored, pink-orange when wet, and with or without setae. Setae were hyaline, acicular, 60 to 100 μm long, and had a base that was 4 to 6 μm wide. Conidiophores were in a dense fascicle, not branched, hyaline, aseptate or uniseptate, and 8 to 20 × 2 to 3.5 μm. Conidia were long, ellipsoid to cylindric, fusiform, rounded at the apex, subtruncate at the base, straight to slightly bent, guttulate, hyaline, aseptate, 11 to 26 × 2.5 to 4.0 μm. A single-conidial isolate formed cream-colored colonies that turned into salmon-colored colonies on potato dextrose agar (PDA). Morphological and cultural characteristics of the fungus were consistent with previous reports of Pseudonectria pachysandricola B.O. Dodge (1,3,4). Voucher specimens were housed at Korea University (KUS). Two isolates, KACC46110 (ex KUS-F25663) and KACC46111 (ex KUS-F25683), were accessioned in the Korean Agricultural Culture Collection. 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 using ABI Prism 337 automatic DNA sequencer (Applied Biosystems, Foster, CA). The resulting sequence of 487 bp was deposited in GenBank (Accession No. JN797821). This showed 100% similarity with a sequence of P. pachysandricola from the United States (HQ897807). Isolate KACC46110 was used in pathogenicity tests. Inoculum was prepared by harvesting conidia from 2-week-old cultures on PDA. Ten young leaves wounded with needles were sprayed with conidial suspensions (~1 × 106 conidia/ml). Ten young leaves that served as the control were treated with sterile distilled water. Plants were covered with plastic bags to maintain a relative humidity of 100% at 25 ± 2°C for 24 h. Typical symptoms of brown spots appeared on the inoculated leaves 4 days after inoculation and were identical to the ones observed in the field. P. pachysandricola was reisolated from 10 symptomatic leaf tissues, confirming Koch's postulates. No symptoms were observed on control plants. Previously, the disease was reported in the United States, Britain, Japan, and the Czech Republic (2,3), but not in Korea. To our knowledge, this is the first report of P. pachysandricola on Pachysandra terminalis in Korea. Since this plant is popular and widely planted in Korea, this disease could cause significant damage to nurseries and the landscape. References: (1) B. O. Dodge. Mycologia 36:532, 1944. (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/ , September 24, 2011. (3) I. Safrankova. Plant Prot. Sci. 43:10, 2007. (4) W. A. Sinclair and H. H. Lyon. Disease of Trees and Shrubs. 2nd ed. Cornell University Press, Ithaca, NY, 2005.

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First Report of Alternaria Leaf Spot of Banana Caused by Alternaria alternata in the United States

Plant Disease ◽

10.1094/pdis-01-13-0007-pdn ◽

2013 ◽

Vol 97 (8) ◽

pp. 1116-1116 ◽

Cited By ~ 3

Author(s):

V. Parkunan ◽

S. Li ◽

E. G. Fonsah ◽

P. Ji

Keyword(s):

United States ◽

Alternaria Alternata ◽

Leaf Spot ◽

Morphological Characteristics ◽

The United States ◽

Its Sequencing ◽

Single Spore ◽

First Report ◽

Alternaria Leaf Spot ◽

Leaf Spots

Research efforts were initiated in 2003 to identify and introduce banana (Musa spp.) cultivars suitable for production in Georgia (1). Selected cultivars have been evaluated since 2009 in Tifton Banana Garden, Tifton, GA, comprising of cold hardy, short cycle, and ornamental types. In spring and summer of 2012, 7 out of 13 cultivars (African Red, Blue Torres Island, Cacambou, Chinese Cavendish, Novaria, Raja Puri, and Veinte Cohol) showed tiny, oval (0.5 to 1.0 mm long and 0.3 to 0.9 mm wide), light to dark brown spots on the adaxial surface of the leaves. Spots were more concentrated along the midrib than the rest of the leaf and occurred on all except the newly emerged leaves. Leaf spots did not expand much in size, but the numbers approximately doubled during the season. Disease incidences on the seven cultivars ranged from 10 to 63% (10% on Blue Torres Island and 63% on Novaria), with an average of 35% when a total of 52 plants were evaluated. Six cultivars including Belle, Ice Cream, Dwarf Namwah, Kandarian, Praying Hands, and Saba did not show any spots. Tissue from infected leaves of the seven cultivars were surface sterilized with 0.5% NaOCl, plated onto potato dextrose agar (PDA) media and incubated at 25°C in the dark for 5 days. The plates were then incubated at room temperature (23 ± 2°C) under a 12-hour photoperiod for 3 days. Grayish black colonies developed from all the samples, which were further identified as Alternaria spp. based on the dark, brown, obclavate to obpyriform catenulate conidia with longitudinal and transverse septa tapering to a prominent beak attached in chains on a simple and short conidiophore (2). Conidia were 23 to 73 μm long and 15 to 35 μm wide, with a beak length of 5 to 10 μm, and had 3 to 6 transverse and 0 to 5 longitudinal septa. Single spore cultures of four isolates from four different cultivars were obtained and genomic DNA was extracted and the internal transcribed spacer (ITS1-5.8S-ITS2) regions of rDNA (562 bp) were amplified and sequenced with primers ITS1 and ITS4. MegaBLAST analysis of the four sequences showed that they were 100% identical to two Alternaria alternata isolates (GQ916545 and GQ169766). ITS sequence of a representative isolate VCT1FT1 from cv. Veinte Cohol was submitted to GenBank (JX985742). Pathogenicity assay was conducted using 1-month-old banana plants (cv. Veinte Cohol) grown in pots under greenhouse conditions (25 to 27°C). Three plants were spray inoculated with the isolate VCT1FT1 (100 ml suspension per plant containing 105 spores per ml) and incubated under 100% humidity for 2 days and then kept in the greenhouse. Three plants sprayed with water were used as a control. Leaf spots identical to those observed in the field were developed in a week on the inoculated plants but not on the non-inoculated control. The fungus was reisolated from the inoculated plants and the identity was confirmed by morphological characteristics and ITS sequencing. To our knowledge, this is the first report of Alternaria leaf spot caused by A. alternata on banana in the United States. Occurrence of the disease on some banana cultivars in Georgia provides useful information to potential producers, and the cultivars that were observed to be resistant to the disease may be more suitable for production. References: (1) E. G. Fonsah et al. J. Food Distrib. Res. 37:2, 2006. (2) E. G. Simmons. Alternaria: An identification manual. CBS Fungal Biodiversity Center, Utrecht, Netherlands, 2007.

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First Report of Subanguina radicicola, the Root-Gall Nematode Infecting Poa annua Putting Greens in Washington State

Plant Disease ◽

10.1094/pdis-91-7-0905c ◽

2007 ◽

Vol 91 (7) ◽

pp. 905-905 ◽

Cited By ~ 2

Author(s):

N. A. Mitkowski

Keyword(s):

United States ◽

New York ◽

The United States ◽

Washington State ◽

Poa Annua ◽

Golf Course ◽

Severe Damage ◽

Surrounding Water ◽

Putting Greens ◽

First Report

In the fall of 2006, a golf course in Snoqualmie, WA renovated five putting greens with commercially produced Poa annua L. sod from British Columbia, Canada. Prior to the renovation, the greens had been planted with Agrostis stolonifera L. cv. Providence, which was removed during the renovation. In February of 2007, chlorotic patches were observed on the newly established P. annua greens. When the roots were examined, extensive galling was observed throughout plant roots. Galls were slender and twisted in appearance and less than one millimeter long. Upon dissection of washed galls, hundreds of eggs were exuded into the surrounding water droplet and both mature male and female nematodes were observed. Further morphometric examination of males, females, and juvenile nematodes demonstrated that they were Subanguina radicicola (Greef 1872) Paramanov 1967 (1). Amplification of nematode 18S, ITS1, and 5.8S regions, using previously published primers (2), resulted in a 100% sequence match with the publicly available sequence for S. radicicola, GenBank Accession No. AF396366. Each P. annua plant had an average of six galls (with a range of 1 to 8), primarily located within the top 2 cm of the soil. All five new P. annua putting greens at the golf course were infested with the nematode. Additionally, P. annua from two A. stolonifera cv. Providence greens that had not been renovated was infected, suggesting that the population occurred onsite and was not imported from the Canadian sod. S. radicicola has been identified as causing severe damage in New Brunswick, Canada on P. annua putting greens and in wild P. annua in the northwestern United States, but to our knowledge, this is the first report of the nematode affecting P. annua on a golf course in the United States. References: (1) E. L. Krall. Wheat and grass nematodes: Anguina, Subanguina, and related genera. Pages 721–760 in: Manual of Agricultural Nematology. Marcel Dekker, New York, 1991. (2) N. A. Mitkowski et al. Plant Dis. 86:840, 2002.

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