First Report of Powdery Mildew Caused by Erysiphe pulchra on Cornus florida in Italy

Cornus florida L. (Cornaceae), flowering dogwood, is a small deciduous tree whose showy inflorescences, clusters of bright red fruits and red and purple leaves in autumn, make it a much appreciated ornamental. During the summer of 2008, severe outbreaks of a previously unknown powdery mildew were observed in several gardens and nurseries in Piedmont (northern Italy). Young leaves were covered with dense, white mycelia and conidia, especially on the adaxial surface. As the disease progressed, infected leaves turned red. Conidia were hyaline, elliptical, borne singly, and measured 32 to 46 × 15 to 20 (average 38 × 17) μm. Conidiophores measured 68 to 77 × 8 to 9 (average 73 × 8) μm, with a cylindrical foot cell measuring 26 to 37 × 8 to 10 (average 31 × 9) μm, followed by two shorter cells. Fibrosin bodies were absent. No chasmothecia were observed. The ITS region (internal transcribed spacer) of rDNA was amplified using primers ITS4/ITS6 and sequenced. The 627-bp sequence (Accession No. EU FJ436989 in GenBank) has 99% identity with Erysiphe pulchra. As proof of pathogenicity, diseased leaves were pressed against leaves of three healthy 3-year-old plants. Three noninoculated plants served as controls. Inoculated and noninoculated plants were maintained outdoors at 13 to 21°C. After 15 days, typical powdery mildew colonies developed on inoculated plants. Noninoculated plants did not show symptoms. The pathogenicity test was carried out twice. To our knowledge, this is the first report of the presence of powdery mildew on C. florida caused by E. pulchra in Italy. Powdery mildew of dogwood, caused by Microsphaera (Erysiphe) pulchra, has been reported in the United States (3) and Japan (1). In Italy, a powdery mildew caused by an Oidium sp. has been reported on C. sanguinea (2). Herbarium specimens of this disease are available at AGROINNOVA Collection, University of Torino, Italy. References: (1) T. Kobayashi. Index of Fungi Inhabiting Woody Plants in Japan. Host, Distribution, and Literature. Zenkoku-Noson-Kyoikai Publishing Co., Ltd., Tokyo, 2007. (2) G. Sicoli et al. Inf. Agrario 56/48:84, 2000. (3) V. L. Smith. Plant Dis. 83:782, 1999.

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First Report of Powdery Mildew Incited by Erysiphe heraclei on English Ivy (Hedera helix) in Italy

Plant Disease ◽

10.1094/pdis-92-2-0313a ◽

2008 ◽

Vol 92 (2) ◽

pp. 313-313 ◽

Cited By ~ 1

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

J. Rossi ◽

M. L. Gullino

Keyword(s):

Nucleotide Sequence ◽

Powdery Mildew ◽

Its Region ◽

The United States ◽

Tube Length ◽

Herbarium Specimens ◽

Pathogenicity Test ◽

Hedera Helix ◽

First Report ◽

Germ Tubes

Hedera helix L. (Araliaceae) is a common ornamental species that is able to grow in shaded areas and is often used in parks and gardens. During the fall of 2006, severe outbreaks of a previously unknown powdery mildew were observed in several gardens in Liguria (northern Italy). Both surfaces of young leaves of affected plants were covered with dense, white mycelia and conidia. As the disease progressed, infected leaves turned yellow and dropped. Mycelia and conidia were also observed on young stems. Conidia were hyaline, cylindrical, borne singly, and measured 38 to 51 × 12 to 18 (average 42 × 16) μm. Single germ tubes, moderately long (average 26 μm), developed at the end of conidia. Appressoria of germ tubes and hyphae were lobed (three to four lobes). Conidiophores, 68 to 82 × 7 to 8 (average75 × 8) μm, showed foot cells measuring 39 to 60 × 7 to 8 (average 52 × 8) μm, followed by one shorter cell measuring 19 to 28 × 8 to 9 (average 23 × 9) μm. Fibrosin bodies were absent. Chasmothecia were numerous, spherical, amber-colored then brown at maturity, with diameters ranging from 97 to 140 (average 120) μm, containing four asci shortly stalked, 57 to 72 × 32 to 51 (average 65 × 41 μm). Ascospores were ellipsoid and measured 24 to 34 × 15 to 20 (average 30 × 17) μm. The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 613-bp fragment showed an E-value of 0.0 with Erysiphe heraclei. The nucleotide sequence has been assigned GenBank Accession No. EU 010381. In GenBank, our nucleotide sequence shows an E-value of 0.0 also with E. betae. However, the comparison of appressorium shape and germ tube length observed on our microorganism with those described for E. betae by Braun (2) suggests that the causal agent of the powdery mildew reported on ivy is E. heraclei. Furthermore, symptoms described on our host, appressorium shape and the length of conidiophores, are different from those of Oidium araliacearum described by Braun (2) on Araliaceae. Inoculations were made by gently pressing diseased leaves onto leaves of five healthy H. helix plants. Three noninoculated plants served as controls. Inoculated and noninoculated plants were maintained in a greenhouse at temperatures between 21 and 25°C. After 15 days, typical powdery mildew colonies developed on inoculated plants. Noninoculated plants did not show symptoms. The pathogenicity test was carried out twice. To our knowledge, this is the first report of the presence of powdery mildew on H. helix caused by E. heraclei in Italy. A powdery mildew caused by E. cichoracearum was previously reported on H. canariensis var. azorica in Italy (3), while a powdery mildew on H. helix caused by O. araliacearum and Golovinomyces orontii, respectively, were observed in the United States (4) and Germany. Herbarium specimens of this disease are available at AGROINNOVA Collection, University of Torino, Italy. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) U. Braun. A Monograph of the Erysiphaceae (Powdery Mildews). Cramer, Berlin, Germany, 1987. (3) C. Nali. Plant Dis. 83:198, 1999. (4) G. S. Saenz and S. T. Koike. Plant Dis. 82:127, 1998.

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First Report of Botrytis Blight Caused by Botrytis cinerea on Flowering Dogwood (Cornus florida) in Italy

Plant Disease ◽

10.1094/pdis-93-5-0549c ◽

2009 ◽

Vol 93 (5) ◽

pp. 549-549 ◽

Cited By ~ 1

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

Botrytis Cinerea ◽

Morphological Characteristics ◽

Its Region ◽

The United States ◽

Deciduous Tree ◽

Fluorescent Light ◽

Cornus Florida ◽

First Report ◽

Flowering Dogwood ◽

Botryotinia Fuckeliana

Flowering dogwood (Cornus florida L., Cornaceae), is a small deciduous tree whose showy inflorescences, clusters of bright red fruits and red and purple leaves in autumn, make it a much appreciated ornamental. In June of 2008, severe outbreaks of a previously unknown blight were observed in several private gardens near Biella (northern Italy) after a rainy spring with temperatures that ranged from 7 to 25°C. Dogwoods in the gardens were 10 to 15 years old, and the disease was observed on 20 to 30% of 30 trees. First symptoms consisted of blighted leaves and then shoot dieback. As the disease progressed, entire leaves became necrotic and were covered by an abundant, soft, gray, sporulating mycelium. Tissue fragments of 1 mm2 were excised from the margins of the lesions, immersed in a solution containing 1% sodium hypochlorite, plated on potato dextrose agar (PDA) medium, and incubated under constant fluorescent light at 22 ± 1°C for 10 days. Conidiophores were slender and branched with enlarged apical cells bearing smooth, ash-colored conidia 6 to 10 × 6 to 8 (average 9 × 7) μm on short sterigmata. A few, black, irregularly shaped sclerotia (3 to 5 × 1 to 2 mm) were produced on PDA plates incubated for 20 days at 8 ± 1°C. These morphological characteristics identified the fungus as Botrytis cinerea (2). The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLAST analysis (1) of the 491-bp segment showed a 100% homology with the sequence of Botryotinia fuckeliana (perfect stage of B. cinerea). The nucleotide sequence has been assigned GenBank Accession No. FJ 572049. Pathogenicity tests were performed twice by placing mycelium fragments (1 cm2) of PDA cultures on 30 leaves of 6 healthy 3-year-old potted C. florida plants. Six plants inoculated with PDA alone served as controls. Plants were maintained outdoors at temperatures ranging between 15 and 22°C, spraying leaves with water three times a day. The first foliar lesions similar to those observed in the gardens developed 10 days after inoculation on 23 inoculated leaves, whereas control plants remained healthy. B. cinerea was consistently reisolated from these lesions. To our knowledge, this is the first report of the presence of B. cinerea on C. florida in Italy. The disease has been reported in the United States (4) as well as in Japan (3). At this time, the economic importance of Botrytis blight to flowering dogwoods in Italy is undetermined. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) H. L. Barnett and B. B. Hunter. Illustrated Genera of Imperfect Fungi. Burgess Publishing Company, Minneapolis, MN, 1972. (3) T. Kobayashi. Ann. Phytopathol. Soc. Jpn. 50:528, 1984. (4) C. Westcott. Plants Gard. 7:136, 1951.

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First Report of Powdery Mildew of Platanus occidentalis Caused by Erysiphe platani in Korea

Plant Disease ◽

10.1094/pdis-10-12-0982-pdn ◽

2013 ◽

Vol 97 (6) ◽

pp. 843-843 ◽

Cited By ~ 2

Author(s):

Y. J. La ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

North America ◽

Powdery Mildew ◽

Its Region ◽

The United States ◽

Control Measures ◽

Base Substitution ◽

Width Ratio ◽

First Report ◽

Platanus Occidentalis ◽

Young Leaves

Platanus occidentalis L., called American sycamore or American plane, is native to North America. The trees are commonly planted throughout the world on the sides of roads and in parks. In June 2012, diseased leaves exhibiting signs of powdery mildew from a park in Daegu City of Korea were sent to Plant Clinic of Seoul National University for diagnosis. Our observations in Daegu City during September and October 2012 showed that nearly 99% of the approximately 1,000 trees surveyed were infected with a powdery mildew. Voucher specimens (n = 6) were deposited at the Korea University Herbarium (KUS). Symptoms were characterized by chlorosis, distortion, or cupping of young leaves. White superficial colonies developed amphigenously on leaves. Hyphae were flexuous to straight, branched, septate, 4 to 7 μm wide, and had lobed appressoria. Conidiophores were 120 to 350 × 5 to 7.5 μm and produced conidia singly. Foot-cells of conidiophores were straight, cylindric, and 115 to 200 μm long. Conidia were hyaline, ellipsoid-ovoid, measured 33 to 47.5 × 17.5 to 29 μm with a length/width ratio of 1.5 to 2.0, lacked distinct fibrosin bodies, and showed reticulate wrinkling of the outer walls. Germ tubes were produced on the subterminal position of conidia. No chasmothecia were observed. The structures and measurements were compatible with those of the anamorphic state of Erysiphe platani (Howe) U. Braun & S. Takam. (1). To confirm the identification, the complete internal transcribed spacer (ITS) region of the rDNA from isolate KUS-F26959 was amplified with nested PCR and sequenced. The resulting sequence of 625 bp was deposited in GenBank (Accession No. JX997805). A GenBank BLAST search of this sequence showed only one base substitution with the four sequences (JQ365940 to JQ365943) of E. platani on Platanus spp. Pathogenicity was confirmed through inoculation tests by gently pressing diseased leaves onto young leaves of three 2-year-old disease-free seedlings. Three non-inoculated plants were used as control. Plants were maintained in a greenhouse at 24 to 30°C. Inoculated leaves developed symptoms after 7 days, whereas the control plants remained symptomless. The fungus present on the inoculated leaves was morphologically identical to that observed on the original diseased leaves, fulfilling Koch's postulates. Since E. platani first was recorded in the United States in 1874, it has been regarded as endemic in North America. From the second half of the 20th century, introduction and expansion of the range of this fungus to South America, South Africa, Australia and New Zealand, Europe, and Asia have been reported (1,2). To our knowledge, this is the first report of E. platani infections of P. occidentalis in Korea. This species was recorded on P.× hispanica from Japan in 1999 (4) and on P. orientalis from China in 2006 (3), suggesting invasive spread of the sycamore powdery mildew in East Asia. Since American sycamores are widely planted in Korea, control measures should be made to prevent further spread of the disease. References: (1) U. Braun and R. T. A. Cook. Taxonomic Manual of the Erysiphales (Powdery Mildews), CBS Biodiversity Series No.11. CBS, Utrecht, 2012. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication, ARS, USDA, Retrieved October 22, 2012. (3) C. Liang et al. Plant Pathol. 57:375, 2008. (4) S, Tanda. J. Agric. Sci., Tokyo Univ. Agric. 43:253, 1999.

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First Report of the Teleomorph of an Oidium sp. Causing Powdery Mildew on Flowering Dogwood in South Carolina

Plant Disease ◽

10.1094/pdis.1999.83.2.200b ◽

1999 ◽

Vol 83 (2) ◽

pp. 200-200 ◽

Cited By ~ 3

Author(s):

M. R. Williamson ◽

J. H. Blake

Keyword(s):

South Carolina ◽

Powdery Mildew ◽

Morphological Features ◽

Minor Importance ◽

Cornus Florida ◽

First Report ◽

Flowering Dogwood ◽

Young Leaves ◽

First Time ◽

Leaf Symptoms

Prior to 1994, powdery mildew had rarely been reported on flowering dogwood (Cornus florida) in the southeastern U.S. That year, and every year since, epiphytotics of powdery mildew have occurred. Leaf symptoms include distortion and necrotic areas on young leaves and an increase in red pigmentation surrounding infection sites. Young seedlings may be stunted by this disease and growth of older trees may be slowed (2). In early November, 1996, dogwood (C. florida) trees at 10 locations each in Anderson, Oconee, and Pickens counties in northwestern South Carolina were surveyed for the presence of powdery mildew. Leaves with signs of powdery mildew (white, powdery patches of mycelium, conidiophores, and conidia) were examined with a ×10 hand lens and leaves with cleistothecia were collected and taken back to the laboratory. Numerous leaves from each site were first examined at ×50 on a dissecting microscope to observe gross morphological features of cleistothecia. Then, approximately 10 cleistothecia from each of two sites were examined on a compound microscope at ×100 or higher to make further observations and measurements. Cleistothecial diameter ranged from 75.0 to 92.5 μm (average 81.8 μm). Appendages, which averaged 6 to 11 per cleistothecium, were 110 to 140 μm long (average 125.7 μm) or 1.54 times the cleistothecial diameter. The apices of appendages were dichotomously branched 2 to 3 times and the tips were distinctly re-curved. The stalks were aseptate and hyaline. Cleistothecia contained 3 to 5 asci. Each ascus contained 2 to 6 ascospores measuring 18 to 28 × 13 to 15 μm. Based on these characteristics, the teleomorph was tentatively identified as Microsphaera pulchra. Cleistothecia were found to be slightly smaller and the number of appendages fewer than Braun's lectotype (1), but these differences were judged to be of minor importance. Therefore, we conclude that the teleomorph of the Oidium sp., herein reported on flowering dogwood for the first time in South Carolina, is Microsphaera pulchra References: (1) U. Braun. Nova Hedwigia 89:1, 1987. (2) L. A. Klein et al. Plant Dis. 82:383, 1998.

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First Report of Powdery Mildew Caused by Podosphaera fusca on Coreopsis lanceolata in Italy

Plant Disease ◽

10.1094/pdis-91-9-1203c ◽

2007 ◽

Vol 91 (9) ◽

pp. 1203-1203 ◽

Cited By ~ 1

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

Powdery Mildew ◽

Its Region ◽

The United States ◽

Pathogenicity Test ◽

First Report ◽

Erysiphe Cichoracearum ◽

Blastn Analysis ◽

Voucher Specimens ◽

Sphaerotheca Macularis ◽

Podosphaera Fusca

Coreopsis lanceolata L. (Asteraceae) is an ornamental species grown in parks and gardens and very much appreciated for its long-lasting flowering period. During the summer and fall of 2006, severe outbreaks of a previously unknown powdery mildew were observed on plants in several gardens near Biella (northern Italy). Both surfaces of leaves of the affected plants were covered with dense white mycelia and conidia. As the disease progressed, infected leaves turned yellow and died. Mycelia and conidia also were observed on stems and flower calyxes. Conidia were hyaline, ellipsoid, borne in short chains (5 to 6 conidia per chain) and measured 33 × 20 (27 to 35 × 17 to 22) μm. Conidiophores, 68 × 11 (62 to 76 × 10 to 12) μm, showed the foot cell measuring 50 × 11 (38 to 58 × 10 to 12) μm, followed by one shorter cell measuring 18 × 12 (13 to 19 × 12 to 13) μm. Fibrosin bodies were present. Chasmothecia were spherical and amber with a diameter of 99 (93 to 105) μm. Each chasmothecium contained one ascus with eight ascospores. On the basis of its morphology, the causal agent was determined to be a Podosphaera sp. (1). The ITS region (internal transcribed spacer) of rDNA was amplified using primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 531 bp obtained showed an E-value of 0.0 with Podosphaera fusca (3). The nucleotide sequence has been assigned GenBank Accession No. EF 442023. Pathogenicity was confirmed through inoculations by gently pressing diseased leaves onto leaves of healthy C. lanceolata plants. Three plants were inoculated. Three noninoculated plants served as the control. Plants were maintained in a greenhouse at temperatures ranging from 20 to 28°C. Twelve days after inoculation, typical symptoms of powdery mildew developed on inoculated plants. Noninoculated plants did not show symptoms. The pathogenicity test was carried out twice. To our knowledge, this is the first report of powdery mildew on C. lanceolata in Italy. Species of Coreopsis were previously described as host to Erysiphe cichoracearum, Sphaerotheca macularis and Leveillula taurica and S. fusca (2,4). Voucher specimens are available at the AGROINNOVA Collection, University of Torino. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) U. Braun. A Monograph of the Erysiphaceae (Powdery Mildews). Cramer, Berlin, GDR, 1987. (3) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000 (4) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society. St Paul, MN, 1989.

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First Report of Powdery Mildew Caused by Podosphaera leucotricha on Photinia × fraserii in Italy

Plant Disease ◽

10.1094/pd-89-1362d ◽

2005 ◽

Vol 89 (12) ◽

pp. 1362-1362

Author(s):

A. Garibaldi ◽

G. Gilardi ◽

M. L. Gullino

Keyword(s):

Powdery Mildew ◽

Morphological Characteristics ◽

The United States ◽

Pathogenicity Test ◽

Podosphaera Leucotricha ◽

Public Park ◽

First Report ◽

Golden Delicious ◽

Young Leaves ◽

Voucher Specimens

Photinia × fraserii, belonging to the family Rosaceae, is an evergreen shrub used in parks and gardens. During the spring of 2004, severe outbreaks of a previously unknown powdery mildew were observed in a public park at Torino (northern Italy) on established plantings of this species. The adaxial and abaxial surfaces of leaves were covered with white mycelium and conidia. Stems also had signs of powdery mildew and were chlorotic. As the disease progressed, infected leaves turned yellow and abscised. Conidia formed in chains and were hyaline, ellipsoid, and measured 16.8 to 33.6 × 12.0 to 24.0 μm (average 25.6 × 15.6 μm). On the basis of host, morphological characteristics, and the presence of fibrosin bodies, the pathogen was identified as Podosphaera leucotricha (Ellis & Everth.) E.S. Salmon (2). Pathogenicity was confirmed by inoculating young leaves of 2-year-old Photinia × fraserii plants with a spore suspension (3 × 105 spores per ml). Also, three 3-year-old cv. Golden Delicious potted apple plants were inoculated. Three noninoculated Photinia × fraserii and three noninoculated apple plants sprayed with deionized water served as a control. After inoculation, plants were maintained in a growth chamber at 25°C. After 17 days, powdery mildew symptoms were observed on inoculated plants of Photinia × fraserii and cv. Golden Delicious. Noninoculated plants remained healthy. The pathogenicity test was carried out twice. The pathogenicity on apple supported the identification of the pathogen as P. leucotricha. To our knowledge, this is the first report of powdery mildew on Photinia × fraserii in Italy. P. leucotricha was previously described on Photinia serrulata in Italy (1) and the United States (3). Voucher specimens are available at the AGROINNOVA Collection, University of Torino. References: (1) E. Baldacci. Rev. Appl. Mycol. 16:358, 1937. (2) R. T. A. Cook et al. Mycol. Res. 101:975, 1997. (3) J. A. Milbraith. Rev. Appl. Mycol. 17:751, 1938.

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First Report of Powdery Mildew Caused by Golovinomyces cichoracearum on Orange Coneflower (Rudbeckia fulgida) in Italy

Plant Disease ◽

10.1094/pdis-92-6-0975b ◽

2008 ◽

Vol 92 (6) ◽

pp. 975-975 ◽

Cited By ~ 6

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

S. Frati ◽

M. L. Gullino

Keyword(s):

United States ◽

Powdery Mildew ◽

Its Region ◽

The United States ◽

Flowering Plant ◽

Pathogenicity Test ◽

Public Park ◽

First Report ◽

Golovinomyces Cichoracearum ◽

Blastn Analysis

Rudbeckia fulgida (orange coneflower), a flowering plant belonging to the Asteraceae, is increasingly used as a border in parks and gardens. In September 2007, severe outbreaks of a previously unknown powdery mildew were observed on plants in a public park in Torino (northern Italy). More than 90% of the plants were affected by the disease. Both surfaces of leaves of affected plants were covered with white mycelia and conidia. As the disease progressed, infected leaves turned yellow and wilted. Mycelia and conidia also were observed on stems and flower calyxes. Conidia were hyaline, ellipsoid, borne in chains (as many as three to four conidia per chain) and measured 34 × 23 (30 to 39 × 21 to 25) μm. Conidiophores measured 129 × 12 (89 to 181 × 11 to 13) μm and showed a foot cell measuring 88 × 12 (48 to 129 × 11 to 13) μm followed by two shorter cells. Fibrosin bodies were absent. Chasmothecia were not observed in the collected samples. The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 619 bp showed a 100% homology with the sequence of Golovinomyces cichoracearum (3). The nucleotide sequence has been assigned GenBank Accession No. EU 233820. Pathogenicity was confirmed through inoculations by gently pressing diseased leaves onto leaves of healthy R. fulgida plants. Twenty plants were inoculated. Fifteen noninoculated plants served as the control. Plants were maintained in a greenhouse at temperatures ranging from 18 to 22°C. Eight days after inoculation, typical symptoms of powdery mildew developed on inoculated plants. The fungus observed on inoculated plants was morphologically identical to that originally observed. Noninoculated plants did not show symptoms. The pathogenicity test was carried out twice. To our knowledge, this is the first report of powdery mildew on R. fulgida in Italy. Powdery mildew on Rudbeckia spp. was previously reported in the United States (4), Poland, and more recently, India and Switzerland. Particularly, in Switzerland the disease has been observed on R. laciniata and R. nitida (2). The economic importance of this disease is currently limited. Voucher specimens are available at the AGROINNOVA Collection, University of Torino. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) A. Bolay. Cryptogam. Helv. 20:1, 2005. (3) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000. (4) D. F. Farr et al. Page 82 in: Fungi on Plants and Plants Products in the United States. The American Phytopathological Society, St Paul, MN, 1989.

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First Report of Powdery Mildew Caused by Golovinomyces magnicellulatus var. magnicellulatus on Physalis alkekengi var. franchetii in China

Plant Disease ◽

10.1094/pdis-03-13-0328-pdn ◽

2013 ◽

Vol 97 (10) ◽

pp. 1382-1382 ◽

Cited By ~ 2

Author(s):

C. Liang ◽

H. H. Xing ◽

Z. Liu ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Sequence Data ◽

Morphological Characteristics ◽

Its Region ◽

The United States ◽

Chinese Isolate ◽

Its Sequence ◽

Pathogenicity Test ◽

First Report ◽

Powdery Mildews

Physalis alkekengi var. franchetii (Mast.) Makino, known as Chinese lantern, belonging to Solanaceae, is cultivated for its fruits of medicinal value in East Asia (4). Since July 2010, a powdery mildew has been continuously observed on this plant in Shenyang City in northeastern China. More than 90% of the plants in a garden were affected. Symptoms first appeared as circular to irregular white patches, which progressed to abundant mycelial growth on both sides of leaves and young stems. In the middle of August, chasmothecia were formed abundantly, especially on the lower leaf surface. Voucher specimens were deposited in the herbarium of Qingdao Agricultural University (HMQAU10014, 12047, and 12144). Conidiophores produced 2 to 5 conidia in chains with a sinuate outline, followed by 2 to 3 cells. Foot-cells of conidiophores were straight and 46 to 65 × 9 to 11 μm. Conidia were ellipsoid to barrel-shaped, 26 to 32 × 13 to 15.5 μm, lacked distinct fibrosin bodies, and produced germ tubes on the subterminal position. Chasmothecia were amphigenous, also cauligenous, 100 to 140 μm across, and contained 10 to 25 asci. Appendages were mycelioid, 0.5 to 4 times as long as the chasmothecial diameter, and 1- to 3-septate. Asci were short-stalked, 45 to 64 × 26 to 34 μm, and contained two ascospores of 18 to 25 × 12.5 to 15 μm. The internal transcribed spacer (ITS) region of rDNA was amplified (3) and sequenced. The resulting 600-bp sequence was deposited in GenBank (Accession No. KC488260). A GenBank BLAST search of complete ITS sequence showed 100% identity with that of Golovinomyces orontii on P. alkekengi var. franchetii (AB077647 ex Japan) and >99% similarity with those of G. magnicellulatus on Phlox paniculata (AB077621 ex Japan, AF011303 ex the United States, and GU945756 and GU945757 ex Korea). G. orontii is currently confined to the Golovinomyces isolates on Cichorioideae (1). On the basis of the morphological characteristics and ITS sequence data, the fungus was identified as G. magnicellulatus var. magnicellulatus (U. Braun) V.P. Heluta (1). It was already noted that Golovinomyces isolates on Physalis and Phlox are phylogenetically close each other (3). A pathogenicity test was conducted by gently pressing a diseased leaf onto leaves of five healthy Chinese lanterns. Five non-inoculated plants served as controls. Inoculated plants developed symptoms after 8 days, whereas the control plants remained symptomless. The fungus present on the inoculated plants was morphologically identical to that originally observed on diseased plants, fulfilling Koch's postulates. Powdery mildews of Chinese lantern associated with Golovinomyces species have been known in Korea and Japan (2). A Korean material of Golovinomyces sp. on P. alkekengi var. franchetii was identified as G. magnicellulatus var. magnicellulatus based on morphological characteristics and 100% ITS sequence identity with a Chinese isolate (Shin, unpublished data). To our knowledge, this is the first report of powdery mildew caused by G. magnicellulatus var. magnicellulatus on Chinese lantern in China. References: (1) U. Braun and R. T. A. Cook. Taxonomic Manual of the Erysiphales (Powdery Mildews), CBS Biodiversity Series No.11. CBS, Utrecht, 2012. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication, ARS, USDA, retrieved March 22, 2013. (3) S. Matsuda and S. Takamatsu. Mol. Phylogen. Evol. 27:314, 2003. (4) Y. Zheng et al. Phytochem. Anal. 23:337, 2012.

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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 Phytophthora citrophthora on Penstemon barbatus in Italy

Plant Disease ◽

10.1094/pd-90-1260a ◽

2006 ◽

Vol 90 (9) ◽

pp. 1260-1260 ◽

Cited By ~ 1

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

D. Minerdi ◽

M. L. Gullino

Keyword(s):

Its Region ◽

The United States ◽

Phytophthora Species ◽

Crown Rot ◽

Pathogenicity Test ◽

Phytophthora Citrophthora ◽

First Report ◽

Blastn Analysis ◽

Root And Crown Rot ◽

Pathogenicity Tests

Penstemon barbatus (Cav.) Roth (synonym Chelone barbata), used in parks and gardens and sometimes grown in pots, is a plant belonging to the Scrophulariaceae family. During the summers of 2004 and 2005, symptoms of a root rot were observed in some private gardens located in Biella Province (northern Italy). The first symptoms resulted in stunting, leaf discoloration followed by wilt, root and crown rot, and eventually, plant death. The diseased tissue was disinfested for 1 min in 1% NaOCl and plated on a semiselective medium for Oomycetes (4). The microorganism consistently isolated from infected tissues, grown on V8 agar at 22°C, produced hyphae with a diameter ranging from 4.7 to 5.2 μm. Sporangia were papillate, hyaline, measuring 43.3 to 54.4 × 26.7 to 27.7 μm (average 47.8 × 27.4 μm). The papilla measured from 8.8 to 10.9 μm. These characteristics were indicative of a Phytophthora species. The ITS region (internal transcribed spacer) of rDNA was amplified using primers ITS4/ITS6 (3) and sequenced. BLASTn analysis (1) of the 800 bp obtained showed a 100% homology with Phytophthora citrophthora (R. & E. Sm.) Leonian. The nucleotide sequence has been assigned GenBank Accession No. DQ384611. For pathogenicity tests, the inoculum of P. citrophthora was prepared by growing the pathogen on autoclaved wheat and hemp kernels (2:1) at 25°C for 20 days. Healthy plants of P. barbatus cv. Nano Rondo, 6 months old, were grown in 3-liter pots (one plant per pot) using a steam disinfested substrate (peat/pomix/pine bark/clay 5:2:2:1) in which 200 g of kernels per liter of substrate were mixed. Noninoculated plants served as control treatments. Three replicates were used. Plants were maintained at 15 to 20°C in a glasshouse. The first symptoms, similar to those observed in the gardens, developed 21 days after inoculation, and P. citrophthora was consistently reisolated from infected plants. Noninoculated plants remained healthy. The pathogenicity test was carried out twice with similar results. A nonspecified root and crown rot of Penstemon spp. has been reported in the United States. (2). To our knowledge, this is the first report of P. citrophthora on P. barbatus in Italy as well as in Europe. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997 (2) F. E. Brooks and D. M. Ferrin. Plant Dis. 79:212, 1995. (3) D. E. L. Cooke and J. M. Duncan. Mycol. Res. 101:667, 1997. (4) H. Masago et al. Phytopathology 67:425, 1977.

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