First Report of Blueberry Botrytis Blight in Buenos Aires, Entre Ríos, and Córdoba, Argentina

Since 2003, a new field disease has been observed on several cultivars of highbush blueberry (Vaccinium corymbosum L.) in Buenos Aires (Baradero, Colonia Urquiza, Lima, Mercedes, and San Pedro), Entre Ríos (Concordia, Gualeguaychú, and Larroque), and Córdoba (Capilla del Monte and La Cumbre). Infected flowers turned brown to tan with a water-soaked appearance and shriveled up. Blighted flowers typically did not produce fruits; even an entire cluster of berries could be aborted. A chlorotic area, that later became necrotic and turned light brown, developed when leaves were in contact with blighted flowers. A watery rot developed on fruit occasionally before harvest but more generally after harvest. Infected tender green twigs also became blighted, with leaf tissue becoming brown to black. Older twigs and stems were also blighted. Abundant, gray mycelium with conidial masses developed on all affected tissues under moist conditions. Sections of infected leaves, twigs, stems, flowers, and fruits were surfaced sterilized with 0.2% NaOCl, plated on 2% potato dextrose agar (pH 7), and incubated at 22°C. Pure cultures formed a whitish dense mycelial mat and turned gray after 72 h. Conidia were ellipsoid, hyaline, nonseptate, and formed on botryose heads. They ranged from 5.8 to 9 × 8.1 to 13.7 μm (average 8.6 × 10.2 μm). Black, round, and irregular microsclerotia developed on 7-day-old cultures with an average size of 1.1 × 1.7 mm. Morphological characteristics agree with those described for Botrytis cinerea Pers.:Fr (1). Pathogenicity was tested on 10 12-month-old potted blueberry plants cv. O'Neal by spraying a suspension of 1 × 106 conidia per ml of sterile distilled water. Ten plants used as controls were sprayed with sterile distilled water. Each plant was covered with a transparent polyethylene bag for 48 h and incubated at 20 ± 2°C in humid chambers for 15 days. Lesions similar to those observed in the fields developed after 4 days and asexual fructifications developed after 5 days. The same pathogen was reisolated from the lesions, thus completing Koch's postulates. Water-treated plants remained symptomless. To our knowledge, this is the first report of a disease caused by B. cinerea on blueberry in Buenos Aires, Córdoba, and Entre Ríos provinces of Argentina. References: (1) M. V. Ellis and J. M. Waller. Sclerotinia fuckeliana (conidial state: Botrytis cinerea) No. 431 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1974.

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First Report of Botrytis Gray Mold on Common Calla Lily in Buenos Aires, Argentina

Plant Disease ◽

10.1094/pd-90-0970b ◽

2006 ◽

Vol 90 (7) ◽

pp. 970-970 ◽

Cited By ~ 2

Author(s):

M. C. Rivera ◽

S. E. Lopez

Keyword(s):

South African ◽

Buenos Aires ◽

Pathogenic Fungi ◽

Gray Mold ◽

Distilled Water ◽

First Report ◽

Zantedeschia Aethiopica ◽

Calla Lily ◽

Japanese Quince ◽

Dark Green

Common calla lily (Zantedeschia aethiopica (L.) Spreng., family Araceae) is an evergreen herbaceous South African ornamental plant that forms a tuft of fleshy-stalked, glossy, dark green leaves. At bloom during the summertime, large, funnel-shaped, waxy-white spaths that surround a bright yellow spadix form at the end of high stalks. In August 2003, large, irregular brown spots with a 3- to 4-mm yellow halo were observed on leaves of 10 plants growing near Japanese quince shrubs (Chaenomeles lagenaria (Loisel.) Koidz.) in Escobar, Buenos Aires. Debris of Japanese quince petals were attached to the center of the lesions with profuse sporulation of Botrytis cinerea Pers. (1). Pathogen spores were disposed on potato dextrose agar (PDA) and incubated at 22°C. Mycelium was initially whitish and turned gray with age. Black conidiophores bore botryose heads of hyaline, ellipsoid, unicellular conidia, gray in mass, 7.5 to 10.5 μm × 6.8 to 7.5 (average 9.2 to 7 μm). Black, irregular sclerotia formed at random in culture. Inoculum was prepared from 7-day-old cultures on PDA. Six flowering common calla lilies planted in 5-liter plastic pots were inoculated by spraying a suspension of 2.5 × 106 conidia per ml of sterile distilled water. Six healthy plants were sprayed with sterile distilled water. Each plant was covered with a transparent polyethylene bag for 3 days and kept at 21°C under a 12-h photoperiod. After a 12-day incubation period, leaves showed elliptic to irregular brown spots surrounded by yellow halos. Tiny round to irregular brown spots developed on flower spaths that finally blighted. Water-treated plants remained symptomless. Koch's postulates were fulfilled by pathogen reisolation from diseased organs. To our knowledge, this is the first report of B. cinerea on Z. aethiopica in Argentina. Infection efficiency of B. cinerea increases when inoculated petals are positioned on leaves (2), which has epidemiological importance in landscapes with association of plant species that are potential hosts of this pathogen. Reference: (1) M. V. Ellis and J. M. Waller. No. 431 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1974. (2) C. Sirjusingh et al. Plant Dis. 80:154, 1996.

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First Report of a Chaetomella sp. Causing a Leaf Spot on Sansevieria trifasciata in China

Plant Disease ◽

10.1094/pdis-10-12-0993-pdn ◽

2013 ◽

Vol 97 (7) ◽

pp. 992-992 ◽

Cited By ~ 4

Author(s):

Y. L. Li ◽

Z. Zhou ◽

W. Lu ◽

J. R. Ye

Keyword(s):

Leaf Spot ◽

Disease Incidence ◽

Morphological Characteristics ◽

Leaf Tissue ◽

Aerial Mycelium ◽

Control Treatment ◽

Distilled Water ◽

First Report ◽

Potted Plants ◽

Fungal Isolates

Sansevieria trifasciata originates from tropical West Africa. It is widely planted as a potted ornamental in China for improving indoor air quality (1). In February 2011, leaves of S. trifasciata plants in an ornamental market of Anle, Luoyang City, China, were observed with sunken brown lesions up to 20 mm in diameter, and with black pycnidia present in the lesions. One hundred potted plants were examined, with disease incidence at 20%. The symptomatic leaves affected the ornamental value of the plants. A section of leaf tissue from the periphery of two lesions from a plant was cut into 1 cm2 pieces, soaked in 70% ethanol for 30 s, sterilized with 0.1% HgCl2 for 2 min, then washed five times in sterilized distilled water. The pieces were incubated at 28°C on potato dextrose agar (PDA). Colonies of two isolates were brown with submerged hyphae, and aerial mycelium was rare. Abundant and scattered pycnidia were reniform, dark brown, and 200 to 350 × 100 to 250 μm. There were two types of setae on the pycnidia: 1) dark brown setae with inward curved tops, and 2) straight, brown setae. Conidia were hyaline, unicellular, cylindrical, and 3.75 to 6.25 × 1.25 to 2.50 μm. Morphological characteristics suggested the two fungal isolates were a Chaetomella sp. To confirm pathogenicity, six mature leaves of a potted S. trifasciata plant were wounded with a sterile pin after wiping each leaf surface with 70% ethanol and washing each leaf with sterilized distilled water three times. A 0.5 cm mycelial disk cut from the margin of a 5-day-old colony on a PDA plate was placed on each pin-wounded leaf, ensuring that the mycelium was in contact with the wound. Non-colonized PDA discs were placed on pin-wounded leaves as the control treatment. Each of two fungal isolates was inoculated on two leaves, and the control treatment was done similarly on two leaves. The inoculated plant was placed in a growth chamber at 28°C with 80% relative humidity. After 7 days, inoculated leaves produced brown lesions with black pycnidia, but no symptoms developed on the control leaves. A Chaetomella sp. was reisolated from the lesions of inoculated leaves, but not from the control leaves. An additional two potted plants were inoculated using the same methods as replications of the experiment, with identical results. To confirm the fungal identification, the internal transcribed spacer (ITS) region of rDNA of the two isolates was amplified using primers ITS1 and ITS4 (2) and sequenced. The sequences were identical (GenBank Accession No. KC515097) and exhibited 99% nucleotide identity to the ITS sequence of an isolate of Chaetomella sp. in GenBank (AJ301961). To our knowledge, this is the first report of a leaf spot of S. trifasciata caused by Chaetomella sp. in China as well as anywhere in the world. References: (1) X. Z. Guo et al. Subtropical Crops Commun. Zhejiang 27:9, 2005. (2) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, CA, 1990.

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Occurrence of Late Leaf Rust Caused by Pucciniastrum americanum in Red Raspberry (Rubus idaeus) in Buenos Aires, Córdoba, and Entre Ríos, Argentina

Plant Disease ◽

10.1094/pdis-92-4-0653b ◽

2008 ◽

Vol 92 (4) ◽

pp. 653-653 ◽

Cited By ~ 2

Author(s):

X. Lucero ◽

E. R. Wright ◽

B. A. Pérez

Keyword(s):

Leaf Rust ◽

Buenos Aires ◽

Morphological Characteristics ◽

Pathogenic Fungi ◽

Rubus Idaeus ◽

Light Cycle ◽

Red Raspberry ◽

Adaxial Side ◽

Mist Chamber ◽

Entre Rios

In the fall of 2003, severity of late leaf rust in leaves and fruits of red raspberry (Rubus idaeus L.) reached 50% in Buenos Aires (Azul, Baradero, Capilla del Señor, Gral. Rodríguez, Mar del Plata, and Tandil), Córdoba (Villa de Las Rosas), and Entre Ríos (Concordia). The south of Argentina, Río Negro (El Bolsón), and Chubut (El Hoyo, Lago Puelo) remained rust free. The abaxial side of the field infected leaves had pustules filled with masses of yellow spores. Chlorotic areas corresponded in the adaxial side. Urediospores were vacuum harvested from field infected leaves collected in the Tandil area and placed onto a healthy 1-year-old greenhouse-grown plant (cv. Heritage). Spores from a single pustule were increased on plants of the same cultivar. Spores were studied with optic and electronic microscopy. Uredial ostiolar cells were warted, laterally free, and constricted in the middle. The obovoid, echinulate urediospores, from infected leaves averaged 24 × 16 μm (16 to 30 × 11 to 21 μm). Morphological characteristics and spore measurements agreed with those reported for Pucciniastrum americanum (1). Urediniospores were suspended in mineral oil and sprayed onto three raspberry cultivars that were maintained in a darkened mist chamber at 20°C for 48 h and the transferred to a 20°C and 12-h light cycle chamber. Control plants were inoculated with sterile water. There were three replicate plants of each treatment. After 11 days, large sporulating uredia (0.5 mm) were produced on inoculated leaves of cv. Autumn Bliss and smaller uredia (0.1 to 0.3 mm) were produced on cv. Heritage. There were necrotic flecks and the least and smallest uredia were produced on cv. Himbo Queen. No symptoms were present in control plants. To our knowledge, this is the first report of P. americanum causing disease on raspberry in Argentina. Reference: (1) G. F. Laundon and A. F. Rainbow. Pucciniastrum americanum. No. 210 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, England, 1969.

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Hydrangea macrophylla Flower Spot Caused by Botrytis cinerea in Buenos Aires

Plant Disease ◽

10.1094/pdis.2004.88.10.1160c ◽

2004 ◽

Vol 88 (10) ◽

pp. 1160-1160 ◽

Cited By ~ 2

Author(s):

M. C. Rivera ◽

D. E. Morisigue ◽

S. E. Lopez

Keyword(s):

Botrytis Cinerea ◽

Buenos Aires ◽

Unknown Origin ◽

Pathogenic Fungi ◽

Gray Mold ◽

Potato Dextrose Agar ◽

Distilled Water ◽

Sterile Water ◽

Hydrangea Macrophylla ◽

Polyethylene Bags

During the spring of 2003, flower spots were observed on French hydrangea (Hydrangea macrophylla (Thunb.) DC) in CETEFFHO-INTA-JICA experimental greenhouses in Castelar, Argentina. Brown, irregular spots randomly distributed on petals were detected on an old, whiteflowering variety of unknown origin, cultivated by growers. Small pieces of diseased tissue were surface disinfested with 2% NaOCl, plated on 2% potato dextrose agar (PDA) with pH 7, and incubated at 22 to 24°C. Dense, whitish mycelium developed within 48 h and turned gray after 72 h. Conidia were ellipsoid, hyaline, nonseptate, and formed in botryose heads. Spores from 10-day-old colonies that were developed on PDA in test tubes were removed with 4 ml of sterile water per tube. Prior to inoculation, inflorescences were detached and placed in water-filled glass vases. To test pathogenicity, eight healthy inflorescences were sprayed with a 5-ml suspension (2 × 104 conidia per ml of sterile distilled water). Another eight healthy inflorescences were sprayed with sterile distilled water. The inflorescences were maintained at 21°C and covered with polyethylene bags that were removed after 3 days. Brown, circular-to-irregular spots appeared on petals 5 days after inoculation, became coalescent, and covered 50 to 60% of each inflorescence in 8 days. Gray mold consisting of black conidiophores and gray-in-mass conidia was observed 3 days after the development of the symptoms. Controls remained symptomless. The same pathogen was recovered from inoculated flowers and was identified as Botrytis cinerea Pers.:Fr. (1). To our knowledge, this is the first report of this fungus on Hydrangea macrophylla in Argentina. Reference: (1) M. V. Ellis and J. M. Waller. Sclerotinia fuckeliana (condial state: Botrytis cinerea).No. 431 in: Descriptions of Pathogenic Fungi and Bacteria, CMI, Kew, Surrey, UK, 1974.

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First Report of Botrytis Leaf Blight on Eleutherococcus senticosus Caused by Botrytis cinerea in China

Plant Disease ◽

10.1094/pdis-01-14-0031-pdn ◽

2014 ◽

Vol 98 (9) ◽

pp. 1270-1270 ◽

Cited By ~ 4

Author(s):

X. Wang ◽

B. H. Lu ◽

Y. Zhi ◽

L. N. Yang ◽

J. Gao

Keyword(s):

Botrytis Cinerea ◽

Morphological Characteristics ◽

Leaf Tissue ◽

Leaf Blight ◽

Jilin Province ◽

Perennial Herb ◽

Conidial Suspension ◽

Acanthopanax Senticosus ◽

Eleutherococcus Senticosus ◽

First Report

Eleutherococcus senticosus (Acanthopanax senticosus, manyprickle acathopanax) is a perennial herb belonging to the family Araliaceae and is mainly distributed in northeastern China, Siberia, Korea, and Japan. It is used for the treatment of rheumatism and neurasthenia. With the development of its cultivation, many diseases began to occur (2) and a previously unknown leaf blight on manyprickle was first observed in July of 2010 in Linjiang City, Jilin Province. The same symptoms were detected in other areas of Jilin Province, such as Baishan and Hunchun cities. The disease has resulted in serious loss of production of manyprickle acanthopanax, with 5 to 10% of leaves infected. The infection initially manifested as irregular lesions on the tips or margins of the leaves, which gradually developed into a V-shaped blight with concentric rings that was grayish brown in the center and dark brown at the margins. The blight eventually spread to cover one third of the entire leaf. Severely infected leaves were rolled or distorted, eventually desiccated and became brittle. Under continuously humid conditions, scattered gray mycelium and conidia appeared on the surface of affected leaf tissue. To isolate the causal agent, tissues were excised from diseased leaves, immersed in 0.1% mercuric chloride, suspended in sterile water, and plated on potato dextrose agar (PDA). Conidiophores arose singly or in groups, straight or flexuous, septate, with an inflated basal cell and dendriform near the apex, brown to light brown, and measured 5.0 to 10.0 × 100.0 to 150.0 μm (n = 50). Conidia were single-celled, globoid or oval-shaped, colorless, measuring 6.0 to 10.0 × 7.0 to 13.0 μm (n = 50). In culture, dark, irregular sclerotia were produced. The morphological descriptions and measurements of the fungi were similar to Botrytis cinerea (4). The ITS region of rDNA was amplified and sequenced. BLAST analysis of the 567-bp segment (JX840481) showed 100% identity with the sequence of Botryotinia fuckeliana (perfect stage of B. cinerea). To further identify the species of B. cinerea, three nuclear protein-coding genes (G3PDH, HSP60, and RPB2) (3) were sequenced and the sequences (KJ018759, KJ018757, and KJ018755) all showed 100% identity with those of B. fuckeliana. Pathogenicity tests were carried out on potted, healthy, 1-year-old plants (n = 10). A conidial suspension of 105 conidia/ml was sprayed with each strain (five strains total) on five leaves still on plants, and five plants were sprayed with water as controls. Plants were covered with polyethylene bags and incubated for 3 days at 25°C in a greenhouse. Symptoms appeared 7 days after inoculation, and were similar to those originally observed on plants under natural conditions, whereas control plants remained healthy. The pathogen was successfully re-isolated from inoculated leaves and was identified as B. cinerea on the basis of its morphological characteristics and related gene sequences. B. cinerea has been previously reported on E. senticosus in Korea (1). However, to our knowledge, this is the first report of Botrytis leaf blight of E. senticosus caused by B. cinerea in China. These results lay the foundation for the disease control. References: (1) K. J. Choi et al. Korean J. Med. Crop Sci. 15:199, 2007. (2) J. Gao et al. Plant Dis. 95:493, 2011. (3) M. Staats et al. Mol. Biol. Evol. 22:333, 2005. (4) Z. Y. Zhang. Flora Fungorum Sinicorum. 26. Botrytis, Ramularia. Science Press, Beijing, 2006.

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First Report of Flyspeck Caused by Zygophiala wisconsinensis on Sweet Persimmon Fruit in Korea

Plant Disease ◽

10.1094/pdis-12-10-0917 ◽

2011 ◽

Vol 95 (5) ◽

pp. 616-616 ◽

Cited By ~ 1

Author(s):

J. Kim ◽

O. Choi ◽

J.-H. Kwon

Keyword(s):

Disease Incidence ◽

Morphological Characteristics ◽

Its Rdna ◽

Control Treatment ◽

Diospyros Kaki ◽

Distilled Water ◽

First Report ◽

Persimmon Fruit ◽

Fungal Isolates ◽

Agar Disc

Sweet persimmon (Diospyros kaki L.), a fruit tree in the Ebenaceae, is cultivated widely in Korea and Japan, the leading producers worldwide (2). Sweet persimmon fruit with flyspeck symptoms were collected from orchards in the Jinju area of Korea in November 2010. The fruit had fungal clusters of black, round to ovoid, sclerotium-like fungal bodies with no visible evidence of a mycelial mat. Orchard inspections revealed that disease incidence ranged from 10 to 20% in the surveyed area (approximately 10 ha) in 2010. Flyspeck symptoms were observed on immature and mature fruit. Sweet persimmon fruit peels with flyspeck symptoms were removed, dried, and individual speck lesions transferred to potato dextrose agar (PDA) and cultured at 22°C in the dark. Fungal isolates were obtained from flyspeck colonies on 10 sweet persimmon fruit harvested from each of three orchards. Fungal isolates that grew from the lesions were identified based on a previous description (1). To confirm identity of the causal fungus, the complete internal transcribed spacer (ITS) rDNA sequence of a representative isolate was amplified and sequenced using primers ITS1 and ITS4 (4). The resulting 552-bp sequence was deposited in GenBank (Accession No. HQ698923). Comparison with ITS rDNA sequences showed 100% similarity with a sequence of Zygophiala wisconsinensis Batzer & Crous (GenBank Accession No. AY598855), which infects apple. To fulfill Koch's postulates, mature, intact sweet persimmon fruit were surface sterilized with 70% ethanol and dried. Three fungal isolates from this study were grown on PDA for 1 month. A colonized agar disc (5 mm in diameter) of each isolate was cut from the advancing margin of a colony with a sterilized cork borer, transferred to a 1.5-ml Eppendorf tube, and ground into a suspension of mycelial fragments and conidia in a blender with 1 ml of sterile, distilled water. The inoculum of each isolate was applied by swabbing a sweet persimmon fruit with the suspension. Three sweet persimmon fruit were inoculated per isolate. Three fruit were inoculated similarly with sterile, distilled water as the control treatment. After 1 month of incubation in a moist chamber at 22°C, the same fungal fruiting symptoms were reproduced as observed in the orchards, and the fungus was reisolated from these symptoms, but not from the control fruit, which were asymptomatic. On the basis of morphological characteristics of the fungal colonies, ITS sequence, and pathogenicity to persimmon fruit, the fungus was identified as Z. wisconsinensis (1). Flyspeck is readily isolated from sweet persimmon fruit in Korea and other sweet persimmon growing regions (3). The exposure of fruit to unusual weather conditions in Korea in recent years, including drought, and low-temperature and low-light situations in late spring, which are favorable for flyspeck, might be associated with an increase in occurrence of flyspeck on sweet persimmon fruit in Korea. To our knowledge, this is the first report of Z. wisconsinensis causing flyspeck on sweet persimmon in Korea. References: (1) J. C. Batzer et al. Mycologia 100:246, 2008. (2) FAOSTAT Database. Retrieved from http://faostat.fao.org/ , 2008. (3) H. Nasu and H. Kunoh. Plant Dis. 71:361, 1987. (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 Coniella castaneicola causing leaf blight on blueberry (Vaccinium virgatum) in China

Plant Disease ◽

10.1094/pdis-05-21-1122-pdn ◽

2021 ◽

Author(s):

Jiahao Lai ◽

Guihong Xiong ◽

Bing Liu ◽

Weigang Kuang ◽

Shuilin Song

Keyword(s):

Molecular Identification ◽

Morphological Characteristics ◽

Leaf Blight ◽

Yield Potential ◽

Effective Control ◽

Economic Losses ◽

Distilled Water ◽

First Report ◽

Fungal Isolates ◽

Blight Disease

Blueberry (Vaccinium virgatum), an economically important small fruit crop, is characterized by its highly nutritive compounds and high content and wide diversity of bioactive compounds (Miller et al. 2019). In September 2020, an unknown leaf blight disease was observed on Rabbiteye blueberry at the Agricultural Science and Technology Park of Jiangxi Agricultural University in Nanchang, China (28°45'51"N, 115°50'52"E). Disease surveys were conducted at that time, the results showed that disease incidence was 90% from a sampled population of 100 plants in the field, and this disease had not been found at other cultivation fields in Nanchang. Leaf blight disease on blueberry caused the leaves to shrivel and curl, or even fall off, which hindered floral bud development and subsequent yield potential. Symptoms of the disease initially appeared as irregular brown spots (1 to 7 mm in diameter) on the leaves, subsequently coalescing to form large irregular taupe lesions (4 to 15 mm in diameter) which became curly. As the disease progressed, irregular grey-brown and blighted lesion ran throughout the leaf lamina from leaf tip to entire leaf sheath and finally caused dieback and even shoot blight. To identify the causal agent, 15 small pieces (5 mm2) of symptomatic leaves were excised from the junction of diseased and healthy tissue, surface-sterilized in 75% ethanol solution for 30 sec and 0.1% mercuric chloride solution for 2 min, rinsed three times with sterile distilled water, and then incubated on potato dextrose agar (PDA) at 28°C for 5-7 days in darkness. Five fungal isolates showing similar morphological characteristics were obtained as pure cultures by single-spore isolation. All fungal colonies on PDA were white with sparse creeping hyphae. Pycnidia were spherical, light brown, and produced numerous conidia. Conidia were 10.60 to 20.12 × 1.98 to 3.11 µm (average 15.27 × 2.52 µm, n = 100), fusiform, sickle-shaped, light brown, without septa. Based on morphological characteristics, the fungal isolates were suspected to be Coniella castaneicola (Cui 2015). To further confirm the identity of this putative pathogen, two representative isolates LGZ2 and LGZ3 were selected for molecular identification. The internal transcribed spacer region (ITS) and large subunit (LSU) were amplified and sequenced using primers ITS1/ITS4 (Peever et al. 2004) and LROR/LR7 (Castlebury and Rossman 2002). The sequences of ITS region (GenBank accession nos. MW672530 and MW856809) showed 100% identity with accessions numbers KF564280 (576/576 bp), MW208111 (544/544 bp), MW208112 (544/544 bp) of C. castaneicola. LSU gene sequences (GenBank accession nos. MW856810 to 11) was 99.85% (1324/1326 bp, 1329/1331 bp) identical to the sequences of C. castaneicola (KY473971, KR232683 to 84). Pathogenicity was tested on three blueberry varieties (‘Rabbiteye’, ‘Double Peak’ and ‘Pink Lemonade’), and four healthy young leaves of a potted blueberry of each variety with and without injury were inoculated with 20 μl suspension of prepared spores (106 conidia/mL) derived from 7-day-old cultures of LGZ2, respectively. In addition, four leaves of each variety with and without injury were sprayed with sterile distilled water as a control, respectively. The experiment was repeated three times, and all plants were incubated in a growth chamber (a 12h light and 12h dark period, 25°C, RH greater than 80%). After 4 days, all the inoculated leaves started showing disease symptoms (large irregular grey-brown lesions) as those observed in the field and there was no difference in severity recorded between the blueberry varieties, whereas the control leaves showed no symptoms. The fungus was reisolated from the inoculated leaves and confirmed as C. castaneicola by morphological and molecular identification, fulfilling Koch’s postulates. To our knowledge, this is the first report of C. castaneicola causing leaf blight on blueberries in China. The discovery of this new disease and the identification of the pathogen will provide useful information for developing effective control strategies, reducing economic losses in blueberry production, and promoting the development of the blueberry industry.

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First Report of Colletotrichum gloeosporioides on Chinese Rose in Argentina

Plant Disease ◽

10.1094/pdis.2000.84.12.1345b ◽

2000 ◽

Vol 84 (12) ◽

pp. 1345-1345 ◽

Cited By ~ 1

Author(s):

M. C. Rivera ◽

E. R. Wright ◽

S. Carballo

Keyword(s):

Colletotrichum Gloeosporioides ◽

Buenos Aires ◽

Morphological Characteristics ◽

Disease Prevalence ◽

Potato Dextrose Agar ◽

Conidial Suspension ◽

First Report ◽

Hibiscus Rosa Sinensis ◽

Leaf Drop ◽

Stems And Leaves

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 Leaf Spot of Sweet Basil Caused by Cercospora guatemalensis in Korea

Plant Disease ◽

10.1094/pdis-05-12-0436-pdn ◽

2012 ◽

Vol 96 (10) ◽

pp. 1580-1580

Author(s):

J. H. Park ◽

K. S. Han ◽

J. Y. Kim ◽

H. D. Shin

Keyword(s):

Leaf Spot ◽

Morphological Characteristics ◽

Its Region ◽

Culture Collection ◽

Distilled Water ◽

First Report ◽

Sweet Basil ◽

Organic Farm ◽

Leaf Spots ◽

Close Phylogenetic Relationship

Sweet basil, Ocimum basilicum L., is a fragrant herb belonging to the family Lamiaceae. Originated in India 5,000 years ago, sweet basil plays a significant role in diverse cuisines across the world, especially in Asian and Italian cooking. In October 2008, hundreds of plants showing symptoms of leaf spot with nearly 100% incidence were found in polyethylene tunnels at an organic farm in Icheon, Korea. Leaf spots were circular to subcircular, water-soaked, dark brown with grayish center, and reached 10 mm or more in diameter. Diseased leaves defoliated prematurely. The damage purportedly due to this disease has reappeared every year with confirmation of the causal agent made again in 2011. A cercosporoid fungus was consistently associated with disease symptoms. Stromata were brown, consisting of brown cells, and 10 to 40 μm in width. Conidiophores were fasciculate (n = 2 to 10), olivaceous brown, paler upwards, straight to mildly curved, not geniculate in shorter ones or one to two times geniculate in longer ones, 40 to 200 μm long, occasionally reaching up to 350 μm long, 3.5 to 6 μm wide, and two- to six-septate. Conidia were hyaline, acicular to cylindric, straight in shorter ones, flexuous to curved in longer ones, truncate to obconically truncate at the base, three- to 16-septate, and 50 to 300 × 3.5 to 4.5 μm. Morphological characteristics of the fungus were consistent with the previous reports of Cercospora guatemalensis A.S. Mull. & Chupp (1,3). Voucher specimens were housed at Korea University herbarium (KUS). An isolate from KUS-F23757 was deposited in the Korean Agricultural Culture Collection (Accession No. KACC43980). 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 sequence of 548 bp was deposited in GenBank (Accession No. JQ995781). This showed >99% similarity with sequences of many Cercospora species, indicating their close phylogenetic relationship. Isolate of KACC43980 was used in the pathogenicity tests. Hyphal suspensions were prepared by grinding 3-week-old colonies grown on PDA with distilled water using a mortar and pestle. Five plants were inoculated with hyphal suspensions and five plants were sprayed with sterile distilled water. The plants were covered with plastic bags to maintain a relative humidity of 100% for 24 h and then transferred to a 25 ± 2°C greenhouse with a 12-h photoperiod. 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. guatemalensis was reisolated from symptomatic leaf tissues, confirming Koch's postulates. No symptoms were observed on control plants. Previously, the disease was reported in Malawi, India, China, and Japan (2,3), but not in Korea. To our knowledge, this is the first report of C. guatemalensis on sweet basil in Korea. Since farming of sweet basil has recently started on a commercial scale in Korea, the disease poses a serious threat to safe production of this herb, especially in organic farming. References: (1) C. Chupp. A Monograph of the Fungus Genus Cercospora. Ithaca, NY, 1953. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology & Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , May 5, 2012. (3) J. Nishikawa et al. J. Gen. Plant Pathol. 68:46, 2002.

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First Report of Phytophthora drechsleri Associated with Stem and Foliar Blight of Gynura bicolor in Taiwan

Plant Disease ◽

10.1094/pdis-12-10-0931 ◽

2011 ◽

Vol 95 (7) ◽

pp. 874-874 ◽

Cited By ~ 1

Author(s):

Y. M. Shen ◽

C. H. Chao ◽

H. L. Liu

Keyword(s):

Disease Incidence ◽

Morphological Characteristics ◽

Hyphal Growth ◽

Pathogenicity Test ◽

Distilled Water ◽

First Report ◽

Foliar Blight ◽

Dual Cultures ◽

Phytophthora Drechsleri ◽

Gynura Bicolor

Gynura bicolor (Roxb. ex Willd.) DC., known as Okinawa spinach or hong-feng-cai, is a commonly consumed vegetable in Asian countries. In May 2010, plants with blight and wilt symptoms were observed in commercial vegetable farms in Changhua, Taiwan. Light brown-to-black blight lesions developed from the top of the stems to the petioles and extended to the base of the leaves. Severely infected plants declined and eventually died. Disease incidence was approximately 20%. Samples of symptomatic tissues were surface sterilized in 0.6% NaOCl and plated on water agar. A Phytophthora sp. was consistently isolated and further plated on 10% unclarified V8 juice agar, with daily radial growths of 7.6, 8.6, 5.7, and 2.4 mm at 25, 30, 35, and 37°C, respectively. Four replicates were measured for each temperature. No hyphal growth was observed at 39°C. Intercalary hyphal swellings and proliferating sporangia were produced in culture plates flooded with sterile distilled water. Sporangia were nonpapillate, obpyriform to ellipsoid, base tapered or rounded, and 43.3 (27.5 to 59.3) × 27.6 (18.5 to 36.3) μm. Clamydospores and oospores were not observed. Oospores were present in dual cultures with an isolate of P. nicotianae (p731) (1) A2 mating type, indicating that the isolate was heterothallic. A portion of the internal transcribed spacer sequence was deposited in GenBank (Accession No. HQ717146). The sequence was 99% identical to that of P. drechsleri SCRP232 (ATCC46724) (3), a type isolate of the species. The pathogen was identified as P. drechsleri Tucker based on temperature growth, morphological characteristics, and ITS sequence homology (3). To evaluate pathogenicity, the isolated P. drechsleri was inoculated on greenhouse-potted G. bicolor plants. Inoculum was obtained by grinding two dishes of the pathogen cultured on potato dextrose agar (PDA) with sterile distilled water in a blender. After filtering through a gauze layer, the filtrate was aliquoted to 240 ml. The inoculum (approximately 180 sporangia/ml) was sprayed on 24 plants of G. bicolor. An equal number of plants treated with sterile PDA processed in the same way served as controls. After 1 week, incubation at an average temperature of 29°C, blight and wilt symptoms similar to those observed in the fields appeared on 12 inoculated plants. The pathogen was reisolated from the lesions of diseased stems and leaves, fulfilling Koch's postulates. The controls remained symptomless. The pathogenicity test was repeated once with similar results. G. bicolor in Taiwan has been recorded to be infected by P. cryptogea (1,2), a species that resembles P. drechsleri. The recorded isolates of P. cryptogea did not have a maximal growth temperature at or above 35°C (1,2), a distinctive characteristic to discriminate between the two species (3). To our knowledge, this is the first report of P. drechsleri being associated with stem and foliar blight of G. bicolor. References: (1) P. J. Ann. Plant Pathol. Bull. 5:146, 1996. (2) H. H. Ho et al. The Genus Phytophthora in Taiwan. Institute of Botany, Academia Sinica, Taipei, 1995. (3) R. Mostowfizadeh-Ghalamfarsa et al. Fungal Biol. 114:325, 2010.

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