First Report of Colletotrichum gloeosporioides on Chinese Rose in Argentina

Chinese rose (Hibiscus rosa-sinensis L.) is a shrub frequently planted in Argentina. In November 1999, dieback and anthracnose symptoms were detected on stems and leaves of plants cv. Hawaii cultivated in Buenos Aires. Disease prevalence was 50%. Pieces of infected tissues were surface-sterilized for 1 min in 2% NaOCl, plated on potato-dextrose agar and incubated at 24 ± 2°C. The isolate that was consistently recovered from diseased tissues was identified as Colletotrichum gloeosporioides (Penz.) Penz. and Sacc., based on morphological characteristics (1,2). Teleomorph stage was not observed. Inoculation for pathogenicity testing was carried out by spraying a conidial suspension (6.5 × 106 conidia per ml) on plants with previously punctured leaves and pruned stems. Inoculated plants with unwounded tissues, as well as noninoculated controls, were included. Five replications of each treatment were done. Plants were incubated in moist chambers at 24°C. Whitish areas of 0.3 to 0.5 cm diameter surrounded by a purple halo developed on all punctured leaves within 10 days. Stem blight and leaf drop were observed. The center of the lesions was covered by black acervuli 14 days after inoculation. Unwounded and noninoculated controls remained symptomless. The pathogen was reisolated from inoculated leaves, completing Koch's postulates. This is the first report of C. gloeosporioides causing disease on Chinese rose in Argentina. References: (1) J. A. Bailey and M. J. Jeger, eds. 1992. Colletotrichum. CAB International, Surrey, England. (2) B. C. Sutton. 1980. The Coelomycetes. CMI, Kew.

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First Report of Azalea Petal Blight Caused by Pestalotiopsis guepini in Argentina

Plant Disease ◽

10.1094/pdis.2000.84.1.100c ◽

2000 ◽

Vol 84 (1) ◽

pp. 100-100 ◽

Cited By ~ 6

Author(s):

M. C. Rivera ◽

E. R. Wright

Keyword(s):

Buenos Aires ◽

Morphological Characteristics ◽

Potato Dextrose Agar ◽

Commonwealth Mycological Institute ◽

Conidial Suspension ◽

Koch’S Postulates ◽

First Report ◽

Pure Cultures ◽

Pathogenicity Testing ◽

Koch's Postulates

The most important azalea (Rhododendron spp.) growing area in Argentina is located in the outskirts of Buenos Aires. A disease of the azalea flower was detected during surveys conducted during September 1998. Irregular brown spots were uniformly distributed on petals and resulted in a flower blight that did not lead to abscission of petals. Pieces of infected petals were surface-sterilized for 1 min in 2% NaOCl, plated on potato dextrose agar, and incubated at 24 ± 2°C. Pure cultures were identified as Pestalotiopsis guepini (Desmaz.) Steyaert (synamorph P. guepini Desmaz.) based on morphological characteristics (1,2). Inoculation for pathogenicity testing was carried out by spraying a conidial suspension (1 × 106 conidia per ml) on plants with previously punctured petals. Inoculated plants with unwounded flowers, as well as noninoculated controls, were included. Plants were incubated in moist chambers at 24°C. Symptoms appeared on all punctured flowers within 4 to 5 days. Petals were blighted by 9 days after inoculation and were covered with black acervuli by 12 days after inoculation. Unwounded and noninoculated controls remained symptomless. The pathogen was reisolated from inoculated flowers, completing Koch's postulates. Pathogenicity of P. guepini on azalea leaves in Argentina was reported in 1991. This is the first report of P. guepini causing disease on azalea flowers in Argentina. References: (1) J. E. M. Mordue. CMI Descr. Pathog. Fungi Bact. No. 320, 1971. (2) B. C. Sutton. 1980. The Coelomycetes. Commonwealth Mycological Institute, Kew, England.

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First Report of Anthracnose of Salsola tragus Caused by Colletotrichum gloeosporioides in Russia

Plant Disease ◽

10.1094/pdis-92-9-1366b ◽

2008 ◽

Vol 92 (9) ◽

pp. 1366-1366 ◽

Cited By ~ 2

Author(s):

T. Kolomiets ◽

O. Skatenok ◽

A. Alexandrova ◽

Z. Mukhina ◽

T. Matveeva ◽

...

Keyword(s):

Colletotrichum Gloeosporioides ◽

Science Research ◽

Research Unit ◽

Internal Transcribed Spacers ◽

Conidial Suspension ◽

Voucher Specimen ◽

First Report ◽

Glucose Agar ◽

Stems And Leaves ◽

C 30

In October of 2006, dying Salsola tragus L. (Russian thistle, tumbleweed), family Chenopodiaceae, plants were found along the Azov Sea at Chushka, Russia. Approximately 40 plants in the area were diseased and almost 80% of these were dying. Plants were approximately 1 m tall × 0.5 m wide. Dying plants had irregular, necrotic lesions along the length of the stems. Leaves of these plants were also necrotic. Lesions on stems and leaves were dark brown and usually coalesced. Diseased stems were cut into 3- to 5-mm pieces, disinfested in 70% ethyl alcohol, and then placed onto the surface of potato glucose agar (PGA). Numerous, waxy, subepidermal acervuli with 110 μm long (mean) black setae were observed in all of the lesions after 2 to 3 days. Conidiophores were simple, short, and erect. Conidia were one-celled, hyaline, ovoid to oblong, falcate to straight, and measured 12.9 to 18.0 × 2.8 to 5.5 μm (mean 15.6 × 4.2 μm). Appressoria formed 24 h after placing conidia on a dialysis membrane over 20% V8 juice agar. Appressoria measured 4.0 to 13.9 × 2.4 to 8.8 μm (mean 7.0 × 5.2 μm). These characters conformed to the description of Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. in Penz. (1). A voucher specimen was deposited with the U.S. National Fungus Collections, Beltsville, MD (BPI 878389). Nucleotide sequences for the internal transcribed spacers (ITS 1 and 2) were deposited in GenBank (Accession No. EU530697) and aligned with ITS sequences of two other isolates from S. tragus. There was 100% similarity to each isolate, one from Greece (Accession No. DQ344621) and one from Hungary (Accession No. EU805538). Axenic cultures on PGA were sent to the Foreign Disease-Weed Science Research Unit, USDA, ARS, Fort Detrick, MD for testing in quarantine. Conidia were harvested from 14-day-old cultures grown on 20% V8 juice agar, and healthy stems and leaves of 30-day-old plants of S. tragus (13 plants) were spray inoculated with an aqueous conidial suspension of 1.0 × 106 conidia/ml plus 0.1% v/v polysorbate 20. Another 13 control plants were sprayed with water and surfactant without conidia. Plants were placed in an environmental chamber at 100% humidity for 16 h in the dark at 25°C. After approximately 24 h, all plants were transferred to a greenhouse at 20 to 25°C, 30 to 50% relative humidity, and natural light augmented by 12-h light periods with 500 W sodium vapor lights. Lesions developed on stems of all inoculated plants after 7 days. After 14 days, nine plants were dead and all inoculated plants were dead after 3 weeks. No symptoms developed on control plants. C. gloeosporioides was reisolated from stem pieces of all inoculated plants, and the morphology of the reisolated pathogen was the same as that of the initially isolated pathogen. To our knowledge, this is the first report of anthracnose caused by C. gloeosporioides on S. tragus in Russia. Reference: (1) B. C. Sutton. Page 15 in: Colletotrichum Biology, Pathology and Control. J. A. Bailey and M. J. Jeger, eds. CAB International, Wallingford, UK, 1992.

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First Report of Anthracnose of Salsola tragus Caused by Colletotrichum gloeosporioides in Greece

Plant Disease ◽

10.1094/pd-90-0971b ◽

2006 ◽

Vol 90 (7) ◽

pp. 971-971 ◽

Cited By ~ 4

Author(s):

D. K. Berner ◽

C. A. Cavin ◽

M. B. McMahon ◽

I. Loumbourdis

Keyword(s):

Biological Control ◽

Colletotrichum Gloeosporioides ◽

Type A ◽

The United States ◽

Ionic Surfactant ◽

Potential Candidate ◽

Conidial Suspension ◽

Type B ◽

First Report ◽

Stems And Leaves

In early October of 2005, dying Salsola tragus L. (Russian thistle, tumbleweed), family Chenopodiaceae, plants were found along the Aegean Sea at Kryopigi Beach, Greece (40°02′29″N, 23°29′02″E, elevation 0 m). All of the 30 to 40 plants in the area were diseased and approximately 80% were dead or dying. All plants were relatively large (approximately 1 m tall × 0.5 m diameter), and living portions of diseased plants were flowering. Dying plants had irregular, necrotic lesions extending the length of the stems. Leaves of these plants were also necrotic. Lesions on stems and leaves were dark brown and usually coalesced. Diseased stem pieces were taken to the European Biological Control Laboratory, USDA, ARS at the American Farm School in Thessaloniki, Greece. There, diseased stem pieces were surface disinfested for 15 min with 0.5% NaOCl and placed on moist filter paper in petri dishes. Numerous, waxy subepidermal acervuli with black setae were observed in all lesions after 2 to 3 days. Conidiophores were simple, short, and erect. Conidia were one-celled, hyaline, ovoid to oblong, falcate to straight, 12.9 to 18.0 × 2.8 to 5.5 μm (mode 16.1 × 4.5 μm). These characters conformed to the description of Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. in Penz. (2). Conidia were placed on modified potato carrot agar and axenic cultures from these isolations were sent to the quarantine facility of the Foreign Disease-Weed Science Research Unit, USDA, ARS, Fort Detrick, MD for testing. On the basis of DNA sequences, two variants within S. tragus have been described in California and named “Type A” and “Type B” (1). Conidia were harvested from 14-day-old cultures grown on 20% V8 juice agar, and healthy stems and leaves of 18 30-day-old plants of S. tragus Type A and 10 Type B plants were spray inoculated with an aqueous conidial suspension (1.0 × 106 conidia/ml plus 0.1% non-ionic surfactant). Three control plants of each type were sprayed with water and surfactant only. Plants were placed in an environmental chamber (18 h of dew in darkness at 25°C). After 1 day, all plants were transferred to a greenhouse (20 to 25°C, 30 to 50% relative humidity, and natural light augmented with 12-h light periods with 500-W sodium vapor lights). Lesions developed on stems of inoculated Type A plants after 5 days. After 14 days, all inoculated Type A plants were dead. Lesions on Type B plants were small and localized; all plants were diseased but no plants died. No symptoms occurred on control plants. C. gloeosporioides was reisolated 14 to 21 days after inoculation from stem pieces of all inoculated plants of both types of S. tragus. This isolate of C. gloeosporioides is a destructive pathogen on S. tragus Type A and is a potential candidate for biological control of this weed in the United States. To our knowledge, this is the first report of anthracnose caused by C. gloeosporioides on S. tragus in Greece. A voucher specimen has been deposited with the U.S. National Fungus Collections, Beltsville, MD (BPI 871126). Nucleotide sequences for the internal transcribed spacers (ITS 1 and 2) were deposited in GenBank (Accession No. DQ344621) and exactly matched sequences of the teleomorph, Glomerella cingulata. References: (1) F. Ryan and D. Ayres. Can. J. Bot. 78:59, 2000. (2) B. C. Sutton. Page 15 in: Colletotrichum Biology, Pathology and Control. J. A. Bailey and M. J. Jeger, eds. CAB International Mycological Institute, Wallingford, UK, 1992.

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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 Anthracnose Caused by Colletotrichum gloeosporioides on Malus prunifolia in Korea

Plant Disease ◽

10.1094/pdis-01-12-0063-pdn ◽

2012 ◽

Vol 96 (5) ◽

pp. 766-766 ◽

Cited By ~ 1

Author(s):

W. Cheon ◽

Y. S. Kim ◽

Y. H. Jeon

Keyword(s):

Colletotrichum Gloeosporioides ◽

Sequence Similarity ◽

Morphological Characteristics ◽

Its Rdna ◽

Plant Diseases ◽

Conidial Suspension ◽

Korean Society ◽

First Report ◽

Malus Prunifolia ◽

Crab Apple

In 2010 and 2011, crab apples in Andong Province, Korea were found with dark brown spots on the fruit and mummified fruit on a tree. The fruit surface had red, circular spots that contained smaller, white spots; the color of the inner spots later changed to brown or black. Eventually, the rotten fruit dried and became mummified. Microscopic examination revealed the presence of acervuli and dark brown-to-black, needle-shaped setae. To isolate potential pathogens from infected fruit, small sections (5 to 10 mm2) were excised from the margins of lesions. These sections were surface sterilized with 70% ethanol and 1% NaOCl for 1 min and then rinsed three times with sterile distilled water. The fungus that was isolated produced whitish mycelia when grown on potato dextrose agar (PDA); the mycelia later became gray to dark gray with aerial mycelia in tufts and numerous conidia were produced. The conidia were straight, cylindrical with an obtuse apex and a truncated base, and measured 11.4 to 17.5 × 4.2 to 7.1 μm. The measurements and taxonomic characteristics coincide with those of Colletotrichum gloeosporioides (Penz.) (1). The isolated fungus was tested for pathogenicity on crab apples and cv. Fuji apples by inoculation with a conidial suspension (105 conidia/ml) prepared from 20-day-old PDA cultures. A 20-μl drop of the conidial suspension was placed onto crab apple and apple fruits that had been wounded by piercing them 1 to 2 mm deep with a pin. Small, dark lesions were observed on the artificially inoculated fruit 3 days after inoculation. Nine days after inoculation, dark lesions with salmon-colored masses of conidia were observed on fruit, which were also soft and sunken. Abundant masses of conidia were produced in the decayed tissues. The fungus was reisolated from the parts of the fruits showing the symptoms. The internal transcribed spacer (ITS) rDNA of the isolated fungus was amplified and sequenced by PCR as described by White et al. (2). The resulting 582-bp of ITS rDNA sequence was deposited in GenBank (Accession No. JQ405742). A BLAST analysis for sequence similarity of the ITS region revealed 100% identity with nucleotide sequences for C. gloeosporioides isolates (Accession Nos. HQ645080 and AB458667). The results obtained on morphological characteristics, pathogenicity, and molecular data corresponded with those of C. gloeosporioides described by Sutton (1). To our knowledge, this is the first report of the presence of C. gloeosporioides on crab apple in Korea (3). Crab apple is used as a pollinator for single-cultivar apple orchards and may become a possible source of inoculum for cultivated apple. References: (1) T. B. Sutton. Compendium of Apple and Pear Diseases. The American Phytopathological Society, St. Paul, MN, 1990. (2) T. J. White et al. PCR Protocols: A Guide to Methods and Applications, Academic Press, Inc., New York, 1990. (3) S. H. Yu. List of Plant Diseases in Korea. 5th ed. (in Korean). The Korean Society of Plant Pathology, 2009.

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First Report of Septoria Blight of Parsley Caused by Septoria petroselini in the Mediterranean Region of Turkey

Plant Disease ◽

10.1094/pdis.2003.87.1.99a ◽

2003 ◽

Vol 87 (1) ◽

pp. 99-99 ◽

Cited By ~ 3

Author(s):

S. Kurt

Keyword(s):

Mediterranean Region ◽

Morphological Characteristics ◽

Potato Dextrose Agar ◽

Distilled Water ◽

Conidial Suspension ◽

Sterile Water ◽

First Report ◽

Foliar Symptoms ◽

Polyethylene Bags ◽

The Mediterranean

During December 2001 to March 2002, Septoria blight of parsley was observed in approximately 500 ha of commercial parsley crops in Arsuz County, Hatay, in the Mediterranean Region of Turkey. Incidence of disease ranged from 42 to 80%. Symptoms included irregularly shaped, grayish brown spots (average 3 to 8 mm diameter) with a slightly darker brown margin of necrotic tissue that developed into tan-to-brown lesions surrounded by chlorotic halo on the leaves. Oval-shaped lesions were observed occasionally on petioles. Lesions contained erumpent, dark brown, flask-shaped pycnidia with the ostiole on the upper surface of the foliage. Thirty samples, consisting of diseased leaves and petioles of parsley, were collected from each field. Infected tissues were surface-sterilized in 1% NaOCl for 2 min, rinsed in sterile distilled water, placed on petri dishes containing potato dextrose agar (PDA), and incubated for 10 to 14 days at 25°C. The fungus formed long, multiseptate (0 to 4), hyaline, filiform conidia (14 to 29 μm × 0.5 to 1.9 μm), and short conidiophores within the pycnidia. Based on the morphological characteristics of the fungus, the pathogen was identified as Septoria petroselini Desm. (1). Monoconidial cultures of 18 isolates were prepared. Pathogenicity was confirmed by brush-inoculating slightly wounded foliage of 5- to 7- week-old parsley plants (cv. Kereviz yapragi) with a conidial suspension (106 conidia per ml of sterile water) of each isolate of S. petroselini. Control plants that were brush-inoculated with distilled water and inoculated plants were placed in clear polyethylene bags that were closed and incubated at 20°C for 48 h. The bags were removed, and plants were maintained in a dew chamber for 21 days at 65 to 70% relative humidity. Foliar symptoms developed 15 days after inoculation and appeared similar to lesions observed in the field. Yellowing and necrosis of leaves was also observed on >60% of inoculated plants. No lesions developed on the control plants. The pathogen was readily reisolated on PDA from inoculated plants. To our knowledge, this is the first report of Septoria blight of parsley in the Mediterranean Region of Turkey. Reference: (1) R. F. Cerkauskas and J. Uyenaka. Plant Dis. 74:1037, 1990.

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First Report of Lentil Ascochyta Blight Caused by Ascochyta lentis in Italy

Plant Disease ◽

10.1094/pdis.1999.83.1.77c ◽

1999 ◽

Vol 83 (1) ◽

pp. 77-77

Author(s):

C. Cappelli ◽

R. Buonaurio ◽

R. Torricelli

Keyword(s):

Lens Culinaris ◽

Ascochyta Blight ◽

Central Italy ◽

Morphological Characteristics ◽

Potato Dextrose Agar ◽

Conidial Suspension ◽

First Report ◽

Ascochyta Lentis ◽

Humidity Chamber ◽

Dry Conditions

In May 1997, ascochyta blight incited by Ascochyta lentis Vassiljevsky was observed at an incidence of less than 5% in lentil (Lens culinaris Medik.) fields in Umbria (Central Italy). Symptoms appeared on leaves and stems as tan spots surrounded by a dark margin. Small black pycnidia that produced a pink exudate containing hyaline, 1 septate, 14.2 to 15.8 × 3.5 μm conidia under high humidity were visible in the center of the spots. The fungus was consistently isolated on potato dextrose agar from diseased leaves or stems. To satisfy Koch's postulates, a conidial suspension (106 conidia per ml) of the fungus was sprayed on leaves of 20-day-old lentil plants (landrace Castelluccio) that were maintained in a humidity chamber for 96 h after inoculation. Lesions resembling symptoms that occurred in the field were observed on plants 3 weeks after inoculation. Symptoms were not observed on control plants sprayed with water. The fungus reisolated from the diseased plants was identical to the original isolates. Based on morphological characteristics of pycnidia and conidia as well as pathogenicity, the fungus was identified as A. lentis. A deep-freeze blotter method (2) was used to detect A. lentis in lentil seeds of 20 local landraces used by Umbrian farmers and two accessions from Canada and Turkey, as well as in seed collected from infected fields. The fungus was present only in the two lentil accessions with an incidence of about 5%. Although the fungus had been isolated from Italian seed germplasm in 1986 (1), this is the first report of ascochyta blight occurring in lentil crops in Italy. The heavy rainfalls that characterize the first stage of lentil cultivation in Umbria are favorable for disease development while hot and dry conditions that usually occur during flowering and maturation prevent the dissemination of inoculum and the infection of the seeds. For these reasons, some Umbrian areas could be more suitable for production of ascochyta-free lentil seeds. References: (1) W. J. Kaiser and R. M. Hannan. Phytopathology 76:355, 1986. (2) T. Limonard. Proc. Int. Seed Test. Assoc. 33:343, 1968.

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First Report of Rhizoctonia solani AG-4-HG-II on Garden Pink in Buenos Aires, Argentina

Plant Disease ◽

10.1094/pdis.2001.85.12.1287d ◽

2001 ◽

Vol 85 (12) ◽

pp. 1287-1287

Author(s):

E. R. Wright ◽

M. C. Rivera ◽

K. Asciutto ◽

L. Gasoni

Keyword(s):

Rhizoctonia Solani ◽

Mycelial Growth ◽

Buenos Aires ◽

Morphological Characteristics ◽

Anastomosis Group ◽

Potato Dextrose Agar ◽

Stem Rot ◽

American Phytopathological Society ◽

Basal Stem Rot ◽

First Report

During 2001, basal stem rot, wilt, and plant death were observed on 30% of the plants in a crop of Dianthus plumarius L. ‘Telstar’ in Buenos Aires. Pieces of diseased stems ≈1 cm long were surface-disinfested in 2% NaOCl for 1 min and cultured on 2% potato dextrose agar (PDA), pH 7, at 22 to 24°C. After 7 days, an identical fungus was consistently isolated from pieces of infected tissue. Colonies initially were white, turned brown after 2 to 3 days, and eventually formed irregularly shaped sclerotia. Cultures exhibited morphological characteristics typical of Rhizoctonia solani Kühn (2) and were identified with known anastomosis group tester isolates (1). Positive anastomosis was observed with tester strains of R. solani AG-4-HG-II. One isolate was tested for pathogenicity by placing two pieces of PDA (1 cm2) containing 7-day-old mycelial growth ≈0.5 cm from the base of healthy 2-month-old plants. Control plants were treated with sterile pieces of PDA using the same procedures. Ten replicate plants were used for each treatment. Plants were maintained at 22 to 24°C under 95 to 100% relative humidity and a 12-h light/dark photoperiod. After 7 days, symptoms developed that were similar to those originally observed, and Koch's postulates were satisfied by reisolating the fungus. To our knowledge, this is the first report of R. solani AG4-HG-II causing disease on D. plumarius in Argentina. References: (1) B. Sneh et al. Identification of Rhizoctonia Species. The American Phytopathological Society, St. Paul, MN, 1991. (2) C. C. Tu and J. W. Kimbrough. Mycologia 65:941, 1973.

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First Report of Colletotrichum gloeosporioides on Russian-thistle

Plant Disease ◽

10.1094/pdis.1998.82.12.1405b ◽

1998 ◽

Vol 82 (12) ◽

pp. 1405-1405 ◽

Cited By ~ 6

Author(s):

I. Schwarczinger ◽

L. Vajna ◽

W. L. Bruckart

Keyword(s):

Colletotrichum Gloeosporioides ◽

Morphological Characteristics ◽

Ground Level ◽

Conidial Suspension ◽

First Report ◽

High Virulence ◽

Pathogenicity Tests ◽

Stem Lesions ◽

And Control ◽

The U.S

A pathogen identified as Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. in Penz. was isolated from foliar and stem lesions on Russian-thistle (Salsola tragus Torner ex L.) collected in Bugac, Hungary, in 1996. Symptoms on leaves and stems began as discrete, sunken, 2- to 10-mm-diameter chlorotic spots, followed by formation of circular buff-colored lesions that eventually coalesced, desiccated, and caused plant tissue death above the lesions. Lesions that occurred near ground level usually killed the plant. Salmon-colored spore masses developed in setose acervuli in the center of the necrotic lesions. Conidia were hyaline, one-celled, falcate to nearly straight, and measured 15 to 25 × 5 to 6 μm. The teleomorph stage of the pathogen (Glomerella cingulata (Stoneman) Spauld. & H. Schrenk) was not observed in the field or on inoculated plants. These morphological characteristics of the isolate were consistent with the description of C. gloeosporioides (1). Pathogenicity was proved by completing Koch's postulates in Hungary and the U.S. Inoculation with conidial suspension (106 conidia per ml) sprayed on S. tragus plants in the greenhouse at the three- to four-leaf stage caused severe necrosis and wilting within 6 days and plant death in 2 weeks. Symptoms did not appear on control plants inoculated with sterile, distilled water. Inoculation test was repeated on 6-week-old plants and at the stage of flowering. All treated plants were killed at both stages within 4 weeks. Because of high virulence and host specificity of this isolate of C. gloeosporioides in preliminary pathogenicity tests it is being evaluated for use as a mycoherbicide for Russian-thistle control in the U.S. This is the first report of C. gloeosporioides causing anthracnose on S. tragus. Reference: (1) B. C. Sutton. Pages 1–27 in: Colletotrichum Biology, Pathology and Control. J. A. Bailei and M. J. Jeger, eds. CAB Int., Wallingford, UK, 1992.

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First Report of Colletotrichum gloeosporioides on Cyclamen persicum in Florida

Plant Disease ◽

10.1094/pdis.1997.81.2.227c ◽

1997 ◽

Vol 81 (2) ◽

pp. 227-227 ◽

Cited By ~ 1

Author(s):

D. J. Norman

Keyword(s):

Sodium Hypochlorite ◽

Colletotrichum Gloeosporioides ◽

Potato Dextrose Agar ◽

Distilled Water ◽

Severe Damage ◽

Cyclamen Persicum ◽

First Report ◽

Lesion Diameter ◽

Plastic Bags ◽

Stems And Leaves

Between March and April of 1996, an estimated 20% of the Cyclamen persicum Mill. grown in Florida were infected with Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. in Penz. Symptoms included extensive lesions on flowers, stems, and leaves. Acervuli containing masses of spores and dark setae were observed within lesions. The most severe damage was observed on the cultivar Red Delight. Infected tissues were dipped into 0.26% sodium hypochlorite for 5 s, blotted dry, embedded in water agar, and incubated at 27 ± 1°C. Hyphal tips that grew from lesions were transferred to potato dextrose agar (PDA) and incubated under cool-white fluorescent lights. Developing colonies were gray and contained masses of orange conidia. Conidia were straight with rounded or bulbous ends and averaged 16.8 (SD 5.2) × 2.25 (SD 0.54) μm. Three isolates were selected to complete Koch's postulates. Conidia of each isolate were obtained from 3-day-old PDA cultures, and suspended in sterile, distilled water (SDW) to 104 conidia/ml. These suspensions were sprayed till runoff with hand sprayers onto C. persicum plants. Plants were incubated in plastic bags for 24 h at 27°C, then placed in a glasshouse. Within 3 days, lesions had developed on flowers; within 7 days, they were visible on stems and leaves. Lesion diameter varied from 2 to 5 mm; however, lesions soon coalesced, causing leaf, stem, and flower death. The fungus was reisolated from acervuli that developed on the flowers, stems, and leaves, following previously outlined procedures. Inoculation tests were repeated once. Symptoms did not appear on controls sprayed with SDW nor was the teleomorph stage of the pathogen observed.

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