First Report of Powdery Mildew Caused by Golovinomyces orontii (Erysiphe orontii) on Lamium galeobdolon in Italy

Lamium galeobdolon L. (Labiatae) is a common ornamental species that grows in shade areas and often used as a ground cover in gardens. During the summer of 2006, severe outbreaks of a previously unknown powdery mildew were observed on all Lamium spp. plants in some gardens near Biella (northern Italy). Both surfaces of the leaves of 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 flowers. Conidia were hyaline, ellipsoid, borne in short chains (with a maximum of five conidia per chain), and measured 29 to 37 × 16 to 20 μm (average 33 × 18 μm). Conidiophores, 91 to 104 μm (average 96 μm) long, showed the foot cell measuring 28 to 49 × 9 to 11 μm (average 38 × 10 μm), followed by three shorter cells measuring 14 to 26 × 9 to 15 μm (average 21 × 11 μm). Fibrosin bodies were absent. Chasmothecia were not observed in the collected samples. The internal transcribed spacer region (ITS) of rDNA was amplified using the primers ITS4/ITS6 (4) and sequenced. BLASTn analysis (1) of the 436 bp obtained showed an E-value of 0.0 with Golovinomyces orontii (Erysiphe orontii.) (3). The nucleotide sequence has been assigned GenBank Accession No. EF 121871. Inoculations were made by gently pressing diseased leaves onto leaves of five healthy L. galeobdolon plants. Five noninoculated plants served as controls. Inoculated and noninoculated plants were maintained in a greenhouse at temperatures between 15 and 28°C. After 10 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 L. galeobdolon caused by G. orontii in Italy. Blumer (2) was able to reproduce powdery mildew symptoms on L. galeobdolon using populations from cucumber, while Braun (3) reported L. galeobdolon as a possible host of E. orontii. 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) S. Blumer. Ber. Schweiz. Bot. Ges. 62:384, 1952. (3) U. Braun. A Monograph of the Erysiphaceae (Powdery Mildews). Cramer, Berlin, GDR, 1987. (4) D. E. L. Cooke and J. M. Duncan. Mycol. Res. 101:667, 1997.

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First Report of Powdery Mildew Caused by Golovinomyces orontii (Erysiphe orontii) on Petunia × hybrida in Italy

Plant Disease ◽

10.1094/pdis-91-5-0632b ◽

2007 ◽

Vol 91 (5) ◽

pp. 632-632

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

Powdery Mildew ◽

Petunia Hybrida ◽

Growth Habit ◽

Ornamental Plants ◽

Its Region ◽

Pathogenicity Test ◽

First Report ◽

Golovinomyces Orontii ◽

Powdery Mildews ◽

Blastn Analysis

Petunia × hybrida (Solanaceae) includes several hybrids that are grown as ornamental plants and are very much appreciated for their long-lasting flowering period. Among those, the variety pendula is often selected because of its hanging growth habit that is favorable for balcony decoration. During the summer of 2005, severe outbreaks of a previously unknown powdery mildew were observed on all petunia plants in several gardens near Biella and Torino (northern Italy). Both surfaces of the leaves of affected plants were covered with white, dense mycelia and conidia. As the disease progressed, infected leaves turned yellow and died. Mycelia also were observed on stems and flowers. Conidia were hyaline, ellipsoid, borne in short chains (with a maximum of four conidia per chain), and measured 27 to 36 × 17 to 21 μm (average 31 × 19 μm). Conidiophores, 130 to 154 μm (average 140 μm) long, showed the foot cell (measuring 42 to 65 × 10 to 12 μm, average 52 × 11 μm) followed by three shorter cells measuring 27 to 30 × 13 to 17 μm (average 29 to 14 μm). Fibrosin bodies were absent. Chasmothecia were not observed in the collected samples. The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 (3) and sequenced. BLASTn analysis (1) of the 588 bp obtained showed an E-value of 0.0 with Golovinomyces orontii (Erysiphe orontii) (2). The nucleotide sequence has been assigned GenBank Accession No. DQ 987491. Inoculations were made by gently pressing diseased leaves onto leaves of five healthy Petunia × hybrida var. pendula plants, belonging to cv. Surfinia. Five noninoculated plants served as controls. Inoculated and noninoculated plants were maintained in a greenhouse at temperatures between 14 and 30°C. After 10 days, typical powdery mildew symptoms 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 P. × hybrida caused by G. orontii in Italy. A powdery mildew of P. × hybrida reported in 1966 in Romania has been attributed to E. cichoracearum (4), while Braun (2) reported P. × hybrida as a possible host of E. orontii. 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, GDR, 1987. (3) D. E. L. Cooke and J. M. Duncan. Mycol. Res. 101:667, 1997. (4) E. Eliade. Reprium nov. Spec. Regni veg.73:43, 1966.

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First Report of Powdery Mildew Caused by Erysiphe (Golovinomyces) orontii on Veronica spicata in Italy

Plant Disease ◽

10.1094/pd-90-0831c ◽

2006 ◽

Vol 90 (6) ◽

pp. 831-831

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

D. Minerdi ◽

M. L. Gullino

Keyword(s):

Powdery Mildew ◽

Its Region ◽

Lower Surface ◽

Pathogenicity Test ◽

Sphaerotheca Fuliginea ◽

First Report ◽

Golovinomyces Orontii ◽

The Family ◽

Blastn Analysis ◽

White Mycelium

Veronica spicata (spike speedwell) is a perennial garden species belonging to the family Scrophulariaceae. During the summer through fall of 2004 and 2005, severe outbreaks of a previously unknown powdery mildew were observed in several gardens near Biella (northern Italy). Upper surfaces of leaves were covered with a white mycelium and conidia, and as the disease progressed, infected leaves turned yellow and died. Very rarely was the mycelium observed on the lower surface of leaves or on petioles and flowers. Foot cell was cylindric and measured 19.2 to 25.7 × 10.8 to 14.3 μm (average 21.9 × 12.0 μm). Conidia were hyaline, ellipsoid, brought in short chains (three conidia per chain), and measured 22.2 to 40.8 × 13.6 to 21.6 μm (average 30.1 × 17.0 μm). Conidiophores measured 45.5 to 74.0 × 10.4 to 11.0 μm (average 59.4 × 10.6 μm). Fibrosin bodies were absent. Cleistothecia were never observed on the samples collected. The ITS region (internal transcribed spacer) of rDNA was amplified using the primers ITS4/ITS6 (3) and sequenced. BLASTn analysis (1) of the 504 bp obtained showed an E-value of 0.0 with Erysiphe (Golovinomyces) orontii (2). The nucleotide sequence has been assigned GenBank Accession No. DQ386696. Pathogenicity was confirmed by gently pressing diseased leaves onto leaves of five healthy Veronica spicata plants. Five noninoculated plants served as controls. Inoculated and noninoculated plants were maintained in a greenhouse where temperatures ranged between 15 and 28°C. After 15 days, typical powdery mildew symptoms 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 V. spicata in Italy. Sphaerotheca fuliginea has been reported as the causal agent of powdery mildew on V. spicata (4). Specimens of this disease are available at DIVAPRA Collection, University of Torino. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) U. Braun. Nova Hedwigia 89:166, 1987. (3) D. E. L. Cooke and J. M. Duncan. Mycol. Res. 101:667, 1997. (4) B. Ing. Mycologist 4:125, 1990.

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First Report of Powdery Mildew Caused by Podosphaera xanthii on Calendula officinalis in Italy

Plant Disease ◽

10.1094/pdis-92-1-0174c ◽

2008 ◽

Vol 92 (1) ◽

pp. 174-174 ◽

Cited By ~ 1

Author(s):

A. Garibaldi ◽

G. Gilardi ◽

M. L. Gullino

Keyword(s):

Powdery Mildew ◽

Its Region ◽

Pathogenicity Test ◽

Podosphaera Xanthii ◽

Calendula Officinalis ◽

First Report ◽

Potted Plants ◽

Blastn Analysis ◽

Voucher Specimens ◽

Pot Marigold

Calendula officinalis L. (Asteraceae) (pot marigold or English marigold) is an ornamental species grown in gardens and as potted plants for the production of cut flower. It was also used in ancient Greek, Roman, Arabic, and Indian cultures as a medicinal herb as well as a dye for fabrics, foods, and cosmetics. During the summer of 2007, severe outbreaks of a previously unknown powdery mildew were observed on plants in several gardens near Biella (northern Italy). Both surfaces of leaves of infected 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, born in short chains (four to six conidia per chain), and measured 27.0 to 32.1 (31.4) × 12.9 to 18.4 (18.2) μm. Conidiophores measured 49 to 77.3 (67.2) × 8 to 13.3 (10.8) μm and showed a foot cell measuring 44 to 59 (51.9) × 9.3 to 12.6 (11.3) μm followed by one shorter cell measuring 15.6 to 18.9 (17.6) × 10.4 to 13.6 (12.2) μm. Fibrosin bodies were present. Chasmothecia were spherical, amber colored, with a diameter of 89 to 100 (94.5) 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. (2). The internal transcribed spacer (ITS) region of rDNA was amplified using the primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 588 bp showed a 100% homology with the sequence of Podosphaera xanthii (2). The nucleotide sequence has been assigned GenBank Accession No. EU100973. Pathogenicity was confirmed through inoculations by gently pressing diseased leaves onto leaves of healthy C. officinalis plants. Five plants were inoculated. Five noninoculated plants served as control. Plants were maintained in a greenhouse at temperatures ranging from 20 to 26°C. Eleven 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. officinalis in Italy. C. officinalis was previously described as a host to Sphaerotheca fuliginea (synonym S. fusca) in Great Britain (4) as well as in Romania (3). 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 and S. Takamatsu. Schlechtendalia 4:1, 2000. (3) E. Eliade. Rev. Appl. Mycol. 39:710, 1960. (4) F. J. Moore. Rev. Appl. Mycol. 32:380, 1953.

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First Report of Powdery Mildew Caused by Golovinomyces cichoracearum on English Daisy (Bellis perennis) in Italy

Plant Disease ◽

10.1094/pdis-92-3-0484a ◽

2008 ◽

Vol 92 (3) ◽

pp. 484-484 ◽

Cited By ~ 1

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. L. Gullino

Keyword(s):

Powdery Mildew ◽

Its Region ◽

Northern Italy ◽

Flowering Plant ◽

Pathogenicity Test ◽

First Report ◽

Golovinomyces Cichoracearum ◽

Blastn Analysis ◽

Commercial Farms ◽

Voucher Specimens

Bellis perennis (English daisy) is a flowering plant belonging to the Asteraceae and is increasingly grown as a potted plant in Liguria (northern Italy). In February 2007, severe outbreaks of a previously unknown powdery mildew were observed on plants in commercial farms at Albenga (northern Italy). Both surfaces of leaves of affected plants were covered with white mycelia and conidia. As the disease progressed, infected leaves turned yellow. Mycelia and conidia also were observed on stems and flower calyxes. Conidia were hyaline, ellipsoid, borne in chains (as many as three conidia per chain), and measured 27.7 × 16.9 (15.0 to 45.0 × 10.0 to 30.0) μm. Conidiophores measured 114.0 × 12.0 (109.0 to 117.0 × 11.0 to 13.0) μm and showed a foot cell measuring 78.0 × 11.0 (72.0 to 80.0 × 11.0 to 12.0) 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 primers ITS4/ITS6 and sequenced. BLASTn analysis (1) of the 415 bp obtained showed an E-value of 7e–155 with Golovinomyces cichoracearum (3). The nucleotide sequence has been assigned the GenBank Accession No. AB077627.1 Pathogenicity was confirmed through inoculations by gently pressing diseased leaves onto leaves of healthy B. perennis plants. Twenty plants were inoculated. Fifteen noninoculated plants served as a control. Plants were maintained in a greenhouse at temperatures ranging from 10 to 30°C. Seven 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 B. perennis in Italy. The disease was already reported in other European countries (2). 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 The Powdery Mildews (Erysiphales) of Europe. Gustav Fischer Verlag, Jena, Germany, 1995. (3) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000.

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First Report of Powdery Mildew Caused by Podosphaera spiraeae on Japanese Spiraea in China

Plant Disease ◽

10.1094/pdis-09-13-0944-pdn ◽

2014 ◽

Vol 98 (4) ◽

pp. 571-571 ◽

Cited By ~ 1

Author(s):

H. H. Xing ◽

C. Liang ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Width Ratio ◽

Pathogenicity Test ◽

Voucher Specimen ◽

First Report ◽

Powdery Mildews ◽

White Spots ◽

Length Width ◽

Qingdao City ◽

Leaf Distortion

Japanese spiraea (Spiraea japonica L.f.), belonging to Rosaceae, is widely planted for its ornamental value in China. Since July 2011, powdery mildew infections on leaves and stems of Japanese spiraea have been noticed in some parks and gardens of Chengyang District in Qingdao City, China (GPS coordinates 36°31′04.22″ N, 120°39′41.92″ E). Symptoms first appeared as white spots covered with mycelium on both side of the leaves and young stems. As the disease progressed, abundant mycelial growth covered the whole shoots and caused growth reduction and leaf distortion with or without reddening. A voucher specimen was deposited in the herbarium of Qingdao Agricultural University (Accession No. HMQAU13013). Hyphae were flexuous to straight, branched, septate, 5 to 7 μm wide, and had nipple-shaped appressoria. Conidiophores arising from the upper surface of hyphal cells produced 2 to 5 immature conidia in chains with a crenate outline. Foot-cells of conidiophores were straight, 60 to 125 × 7 to 9 μm, and followed by 1 to 2 shorter cells. Conidia were ellipsoid-ovoid to doliiform, measured 25 to 32 × 12 to 15 μm with a length/width ratio of 1.8 to 2.6, and had distinct fibrosin bodies. Chasmothecia were not found. The structures and measurements were compatible with the anamorphic state of Podosphaera spiraeae (Sawada) U. Braun & S. Takam. as described before (1). The identity of HMQAU13013 was further confirmed by analysis of nucleotide sequences of the internal transcribed spacer (ITS) regions amplified using the primers ITS1/ITS4 (4). The resulting 564-bp sequence was deposited in GenBank (Accession No. KF500426). A GenBank BLAST search of complete ITS sequence showed 100% identity with that of P. spiraeae on S. cantoniensis (AB525940). A pathogenicity test was conducted through inoculation by gently pressing a diseased leaf onto five healthy leaves of a potted Japanese spiraea. Five non-inoculated leaves served as controls. The plants were maintained in a greenhouse at 22°C. Inoculated leaves developed typical symptoms of powdery mildew after 5 days, but the non-inoculated leaves remained symptomless. The fungus presented on the inoculated plant was morphologically identical to that originally observed on diseased plants, fulfilling Koch's postulates. Powdery mildew of S. japonica caused by P. spiraeae has been recorded in Japan, Poland, and Switzerland (2,3). To our knowledge, this is the first report of powdery mildew caused by P. spiraeae on Japanese spiraea 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, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ September 10, 2013. (3) T. Kobayashi. Index of Fungi Inhabiting Woody Plants in Japan. Host, Distribution and Literature. Zenkoku-Noson-Kyoiku Kyokai Publishing Co. Ltd., Tokyo, 2007. (4) S. Matsuda and S. Takamatsu. Mol. Phylogenet. Evol. 27:314, 2003.

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Outbreak of Powdery Mildew Caused by Erysiphe cruciferarum on Spider Flower (Cleome hassleriana) in Italy

Plant Disease ◽

10.1094/pdis-93-9-0963c ◽

2009 ◽

Vol 93 (9) ◽

pp. 963-963 ◽

Cited By ~ 2

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

Powdery Mildew ◽

Its Region ◽

Herbarium Specimens ◽

Pathogenicity Test ◽

Public Park ◽

Potted Plants ◽

Powdery Mildews ◽

Erysiphe Cruciferarum ◽

Average Size ◽

Germ Tubes

Spider flower (Cleome hassleriana L. [synonym = C. spinosa]) is used as a tall border in parks and gardens worldwide. During July 2008, severe outbreaks of a powdery mildew were observed in a public park in Torino (northern Italy). Leaves were covered with dense, white hyphae and conidia, especially on the adaxial surface. Hyphae were also present on petioles and fruits, but not on petals and stems. As the disease progressed, infected leaves turned chlorotic, curled, and wilted. Conidia were hyaline, cylindrical, single, and measured 31.1 to 48.2 × 12.9 to 17.6 μm (average 37.1 × 15.6 μm). Germ tubes terminating in a moderately lobed appressorium were produced terminally. The cylindrical foot cells of the erect condiophores were 19.2 to 27.8 × 6.5 to 8.6 μm (average 23.3 × 7.7 μm). Fibrosin bodies were absent. Chasmothecia were observed mostly on the lower surfaces of leaves. At maturity, they were dark amber and spherical with a diameter of 92.9 to 151.0 μm (average 121.4 μm). Each chasmothecium contained six stalked asci (average size 63.7 × 35.9 μm). Each ascus contained four ellipsoid ascospores that measured 17.3 to 26.4 × 10.9 to 15.6 μm (average 23.3 × 12.8 μm). The internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS4/ITS6 and sequenced (1). The 602-bp sequence was deposited in GenBank under the Accession No. GQ149478 and was 99% similar to that of Erysiphe cruciferarum (Accession No. EU140958). As proof of pathogenicity, diseased leaves of C. hassleriana were pressed against leaves of three healthy 4-month-old potted plants of the same species for 10 min. Three noninoculated plants served as controls. Inoculated and noninoculated plants were maintained in a greenhouse at 22 to 25°C in isolation. After 11 days, typical powdery mildew colonies developed on inoculated plants. Noninoculated plants did not develop symptoms. The pathogenicity test was repeated once. Powdery mildew on C. hassleriana caused by E. cruciferarum was reported in Italy (2) but the pathogen was not characterized. Herbarium specimens are deposited at AGROINNOVA Collection, University of Torino, Italy. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) U. Braun. The Powdery Mildews (Erysiphales) of Europe. Gustav Fischer Verlag, Jena, Germany, 1995.

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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 Powdery Mildew Caused by Podosphaera xanthii on Sechium edule in Korea

Plant Disease ◽

10.1094/pdis-10-14-1011-pdn ◽

2015 ◽

Vol 99 (1) ◽

pp. 162-162 ◽

Cited By ~ 1

Author(s):

I. Y. Choi ◽

S. S. Cheong ◽

J. H. Joa ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

The United States ◽

Soil Conditions ◽

Width Ratio ◽

Korean Isolate ◽

Pathogenicity Test ◽

First Report ◽

Powdery Mildews ◽

Sechium Edule ◽

Length Width

Sechium edule (Jacq.) Sw. (Cucurbitaceae, chayote, mirliton) is native to Mexico and Central America. Several trials have recently been conducted to determine the ability of chayote cultivars to grow under the climatic and soil conditions of South Korea. In April 2013, chayote plants were observed showing typical symptoms of powdery mildew in a glasshouse in Jeju City, Korea. Powdery mildew colonies were circular to irregular, forming white patches on both sides of the leaves. As the disease progressed, entire leaves were covered with white mycelium, followed by leaf withering and premature senescence. The same symptoms were also found on chayote plants in a polyethylene-film-covered greenhouse in Iksan City, Korea, in 2014. Voucher specimens were deposited in the Korea University Herbarium (KUS-F27289, F27422, F28186). Hyphae were flexuous to straight, branched, septate, and 5 to 7 μm wide. Appressoria on the mycelium were nipple-shaped or nearly absent. Conidiophores were straight, 150 to 240 × 10 to 12 μm and produced three to seven immature conidia in chains with a crenate outline. Foot-cells of conidiophores were straight, cylindric, and 52 to 85 μm long. Conidia were hyaline, ellipsoid-ovoid to barrel-shaped, measured 27 to 36 × 16 to 23 μm with a length/width ratio of 1.3 to 2.0, and had distinct fibrosin bodies. Simple to forked germ tubes were produced from the lateral position of conidia. No chasmothecia were found. These structures are typical of the powdery mildew Euoidium anamorph of the genus Podosphaera. Dimensions of foot-cells and conidia were within the ranges provided for P. xanthii (Castagne) U. Braun & Shishkoff, and the length/width ratio of conidia, appressorial characteristics, and conidial germination patterns also conformed to the standard description (2). To confirm the identification, the complete internal transcribed spacer (ITS) region of rDNA of isolate KUS-F27289 was amplified with primers ITS1 and ITS4 and sequenced directly. The resulting 473-bp sequence was deposited in GenBank (Accession No. KM657960). A GenBank BLAST search of the Korean isolate showed 99% similarity with P. xanthii isolates from cucurbitaceous hosts (e.g., AB774155 to AB774158, AB040321, JQ340082, etc.). Pathogenicity was confirmed through inoculation tests by gently pressing a diseased leaf onto young leaves of three asymptomatic, potted chayote plants. Three non-inoculated plants were used as controls. Plants were maintained in a greenhouse at 24 to 34°C. Inoculated leaves started to develop symptoms after 5 days, whereas the control plants remained symptomless. The pathogenicity test was carried out twice with similar results. Powdery mildews of chayote caused by Podosphaera species have been reported in Australia, South Africa, Portugal, India, China, and the United States (1,3,4). To our knowledge, this is the first report of powdery mildew caused by P. xanthii on chayote in Korea. Since chayote production was only recently started on a commercial scale in Korea, powdery mildew infections may pose a serious threat to the safe production of this vegetable. References: (1) P. Baiswar et al. Australas. Plant Dis. Notes 3:160, 2008. (2) U. Braun and R. T. A. Cook. Taxonomic Manual of the Erysiphales (Powdery Mildews), CBS Biodiversity Series No. 11. CBS, Utrecht, 2012. (3) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab. Online publication, ARS, USDA, Retrieved October 4, 2014. (4) R. Singh et al. Plant Dis. 93:1348, 2009.

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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 Erysiphe cruciferarum on Chinese Cabbage in China

Plant Disease ◽

10.1094/pdis-06-13-0648-pdn ◽

2014 ◽

Vol 98 (3) ◽

pp. 421-421 ◽

Cited By ~ 4

Author(s):

H. H. Zhao ◽

H. H. Xing ◽

C. Liang ◽

X. Y. Yang ◽

S. E. Cho ◽

...

Keyword(s):

Powdery Mildew ◽

Chinese Cabbage ◽

Control Treatment ◽

Width Ratio ◽

Pathogenicity Test ◽

Potential Threat ◽

Voucher Specimen ◽

First Report ◽

Powdery Mildews ◽

Erysiphe Cruciferarum

Chinese cabbage, Brassica rapa ssp. pekinensis (syn. Brassica pekinensis (Lour.) Rupr.), in the Brassicaceae, is an important vegetable grown on about 3 million ha in China. Since 2012, a powdery mildew has been found infecting Chinese cabbage plants (cv. Qingyanchunbai No. 1) after bolting for seed production from autumn through spring 2013 in a greenhouse in Qingdao, China. Symptoms first appeared as circular to irregular white patches on both sides of the leaves, and on stems and pods, often thinly covering the whole surface. A voucher specimen was deposited in the herbarium of Qingdao Agricultural University (Accession No. HMQAU12216). Hyphae were thin-walled, smooth, hyaline, and 4 to 6 μm wide. Appressoria on the mycelia were well developed, lobed, solitary, or in pairs. Conidiophores were erect, cylindrical, 45 to 110 μm long, and comprised 3 to 4 cells. Foot-cells of conidiophores were straight, cylindrical, 16 to 28 μm long, and 7.6 to 10 μm wide. Singly-produced conidia were oblong to cylindrical or somewhat ellipsoid-doliiform, 32 to 56 × 12 to 18 μm, with a length/width ratio of 1.8 to 3.8, with angular/rectangular wrinkling of the outer wall surface, and lacked distinct fibrosin bodies. Germ tubes were produced in the perihilar position of conidia. No chasmothecia were found. These structures are typical of the powdery mildew Pseudoidium anamorph of Erysiphe (2). The specific measurements and characteristics (especially short foot-cells of conidiophores) were consistent with previous records of Erysiphe cruciferarum Opiz ex L. Junell (2,3). To confirm the identification, the complete internal transcribed spacer (ITS) region of rDNA of isolate HMQAU12216 was amplified (4) and sequenced directly. The resulting 649-bp sequence was deposited in GenBank (Accession No. KC878683). A GenBank BLAST search of ITS sequences showed an exact match with those of E. cruciferarum on B. oleracea var. acephala (GU721075) and Oidium sp. on B. pekinensis (AB522714). A pathogenicity test was conducted by gently pressing a symptomatic leaf loaded with conidia onto a leaf of each five, healthy, potted, 40-day-old plants (cv. Qingyanchunbai No. 1). Five non-inoculated plants served as a control treatment. Inoculated plants were isolated from non-inoculated plants in separate rooms in a greenhouse at 20 ± 2°C. Inoculated plants developed signs and symptoms after 10 days, whereas the control plants remained symptomless. The fungus present on the inoculated plants was identical morphologically to that originally observed on diseased plants, thus fulfilling Koch's postulates. Though many Brassica spp. have been known to be infected with E. cruciferarum throughout the world, powdery mildew of Chinese cabbage caused by E. cruciferarum has been reported only in Finland, Germany, and Korea (1,3). To our knowledge, this is the first report of powdery mildew caused by E. cruciferarum on Chinese cabbage in China. Though occurrence of the powdery mildew on Chinese cabbage was noticed in an experimental breeding plot, this finding poses a potential threat to production of this vegetable in China. References: (1) U. Braun. The Powdery Mildews (Erysiphales) of Europe. Gustav Fischer Verlag, Jena, Germany, 1995. (2) U. Braun and R. T. A. Cook. Taxonomic Manual of the Erysiphales (Powdery Mildews), CBS Biodiversity Series No. 11. CBS, Utrecht, 2012. (3) H. J. Jee et al. Plant Pathol. 57:777, 2008. (4) S. Matsuda and S. Takamatsu. Mol. Phylogen. Evol. 27:314, 2003.

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