scholarly journals Powdery Mildew Caused by Golovinomyces cichoracearum on Moth Mullein (Verbascum blattaria) in Italy

Plant Disease ◽  
2011 ◽  
Vol 95 (2) ◽  
pp. 225-225 ◽  
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
M. T. Amatulli ◽  
M. L. Gullino
Keyword(s):  
Powdery Mildew ◽  
Signs And Symptoms ◽  
Its Region ◽  
Northern Italy ◽  
Herbaceous Plant ◽  
Pathogenicity Test ◽  
Powdery Mildew Fungus ◽  
Conidial Morphology ◽  
Golovinomyces Cichoracearum ◽  
Symptoms And Signs

Moth mullein (Verbascum blattaria) is an herbaceous plant belonging to the Scrophulariaceae family. It has alternate, simple leaves on stiffly, erect, green stems. Flowers are yellow or white, borne in summer through fall, and is increasingly used in gardens in low-maintenance borders. During the fall of 2009, 4-month-old plants grown in a greenhouse near Torino (northern Italy) showed signs and symptoms of an unknown powdery mildew. The adaxial leaf surfaces were covered with white mycelia and conidia, while the abaxial surfaces were less infected. As the disease progressed, infected leaves turned yellow and wilted. Mycelia were also observed on stems, petioles, and flower calyxes of inflorescences. Powdery mildew was observed on moth mullein naturally diffused in Italian flora and on V. blattaria var albiflorum cv. White Blush. The same symptoms and signs were observed in summer 2010 on V. blattaria plants grown in a garden near Biella. Conidia were hyaline, elliptical, borne in short chains (as many as five conidia per chain), and measured 35 × 22 (29 to 42 × 19 to 24) μm. Conidiophores were erect with a cylindrical foot cell measuring 147 × 11 (93 to 177 × 10 to 12) μm, followed by one to two shorter cells measuring 23 × 11 (15 to 33 × 10 to 12) μm. 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 (1) (GenBank Accession No. HQ316555). The 542-bp amplicon had 99% homology with the sequence of Golovinomyces cichoracearum (GenBank Accession No. EU819552. Pathogenicity was confirmed through inoculation by gently pressing diseased leaves onto leaves of healthy V. blattaria plants. Five plants were inoculated, while the same number of noninoculated plants served as a control. Plants were maintained at temperatures from 19 to 25°C. Fifteen days after inoculation, symptoms and signs of powdery mildew developed on inoculated plants. The conidial morphology of the powdery mildew fungus that developed on inoculated plants was identical to the conidial morphology observed in the original fungus. Noninoculated plants remained healthy. The pathogenicity test was carried out twice. G. cichoracearum, formerly Erysiphe verbasci (synonym E. cichoracearum), has been reported on V. blattaria in Hungary, Romania, and the former USSR (2,3). In conclusion, to our knowledge, it is the first report of G. cichoracearum affecting moth mullein in northern Italy. The economic importance of this disease is at present limited in Italy because of limited planting of this host. However, the ecological characteristics and flowering of V. blattaria make it interesting for low-maintenance gardens. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) K. Amano. Host Range and Geographical Distribution of the Powdery Mildew Fungi. Japan Scientific Societies Press. Tokyo, 1986. (3) U. Braun. The Powdery Mildews (Erysiphales) of Europe. Gustav Fischer Verlag, Stuttgart, Germany, 1995.

scholarly journals Powdery Mildew Caused by Golovinomyces orontii on Creeping Bellflower (Campanula rapunculoides) in Italy

Plant Disease ◽  
2012 ◽  
Vol 96 (2) ◽  
pp. 291-291 ◽  
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
A. Poli ◽  
M. L. Gullino
Keyword(s):  
Powdery Mildew ◽  
Signs And Symptoms ◽  
Its Region ◽  
Herbaceous Plant ◽  
Pathogenicity Test ◽  
Academic Press ◽  
Powdery Mildew Fungus ◽  
Golovinomyces Orontii ◽  
Conidial Morphology ◽  
Eastern European Countries

Creeping (June) bellflower (Campanula rapunculoides) is an herbaceous plant belonging to the Campunalaceae family. It has showy flowers, which is very much appreciated for gardens and landscaping. During the summer of 2011, 6- to 9-month-old plants grown in a garden near Biella (northern Italy) showed signs and symptoms of an unknown powdery mildew. The adaxial leaf surfaces were covered with white mycelia and conidia, while the abaxial surfaces were less infected. As the disease progressed, infected leaves turned yellow and wilted. Mycelia were also observed on stems, petioles, and flower calyxes of inflorescences. Seventy percent of plants were diseased. Conidia were hyaline, elliptical to ovoid (sometimes doliform), borne in short chains (up to three conidia per chain), and measured 27 to 42 (34) × 16 to 24 (19) μm. Conidiophores were erect with a cylindrical foot cell measuring 64 to 105 (80) × 11 to 12 (11) μm and followed by two shorter cells measuring 17 to 24 (20) × 11 to 15 (13) μm. 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 ITS1F/ITS4 and sequenced (3) (GenBank Accession No. JN639855). The 405-bp amplicon had 98% homology with the sequence of Golovinomyces orontii GQ183948. Pathogenicity was confirmed through inoculation by gently pressing diseased leaves onto leaves of healthy C. rapunculoides plants. Three plants were inoculated while the same number of noninoculated plants served as a control. Plants were maintained outside at temperatures from 10 to 26°C. Fifteen days after inoculation, symptoms and signs of powdery mildew developed on inoculated plants. The conidial morphology of the powdery mildew fungus that developed on inoculated plants was identical to the conidial morphology observed in the original fungus. Noninoculated plants remained healthy. The pathogenicity test was carried out twice. G. orontiii has been reported on C. rapunculoides in several eastern European countries as well as in Switzerland and Germany (1,2). To our knowledge, this is the first report of the disease in Italy. The economic importance of this disease is currently limited in Italy because of limited planting of this host. References: (1) A. Bolay. Cryptogam. Helv. 20:1, 2005. (2) U. Braun. The Powdery Mildews (Erysiphales) of Europe. Gustav Fischer Verlag, Stuttgart, Germany, 1995. (3) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.

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

Plant Disease ◽  
2008 ◽  
Vol 92 (3) ◽  
pp. 484-484 ◽  
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.

scholarly journals Powdery Mildew Caused by Golovinomyces cichoracearum on Paris Daisy (Argyranthemum frutescens) in Italy

Plant Disease ◽  
2008 ◽  
Vol 92 (7) ◽  
pp. 1135-1135
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
S. Frati ◽  
A. Minuto ◽  
M. L. Gullino
Keyword(s):  
Powdery Mildew ◽  
Its Region ◽  
Pathogenicity Test ◽  
Potted Plants ◽  
Erysiphe Cichoracearum ◽  
Golovinomyces Cichoracearum ◽  
Blastn Analysis ◽  
Voucher Specimens ◽  
White Mycelium ◽  
The Impact

Paris daisy (Argyranthemum frutescens), also known as Marguerite daisy, is an economically important crop in the Riviera Ligure (northern Italy) where approximately 18 million potted plants per year are produced for export. During the fall and winter of 2007, Paris daisy ‘Bright Carmen’ plants, started in a greenhouse and growing outside in a commercial nursery at Albenga, showed a previously unknown powdery mildew. Young stems, particularly in the interior portions of the plant, were covered with a white mycelium. As the disease progressed, leaves became covered with the mycelium, resulting in smaller, chlorotic leaves. Conidia were hyaline, cylindrical, borne in chains (two to three conidia per chain) and measured 30 × 12 μm (20 to 34 × 10 to 15 μm). Conidia were generated by conidiophores represented by a foot cell measuring 55 to 101 × 11 to 12 μm followed by two shorter cells measuring 19 to 29 × 11 to 14 and 24 to 33 × 12 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 and sequenced. BLASTn analysis (1) of the 441 bp showed a 100% homology with the sequence of Golovinomyces cichoracearum (= Erysiphe cichoracearum) (3). The nucleotide sequence has been assigned GenBank Accession No. EU486992. Pathogenicity was confirmed through inoculation by gently pressing diseased leaves onto leaves of healthy Paris daisy plants of cvs. Blazer Rose, Bright Carmine, Cherry Harmony, Crowned Rose, Fulvia, Sole Mio, Stella 2000, Summit Pink, and Sun Light. Three plants per cultivar were inoculated, while the same number served as noninoculated controls. The pathogenicity test was carried out twice. Plants were maintained in a greenhouse at temperatures ranging from 15 to 21°C. Fifteen days after inoculation, typical symptoms of powdery mildew developed on inoculated plants of all cultivars, with the exception of Stella 2000. The fungus observed on inoculated plants was morphologically identical to that originally observed. Noninoculated plants did not show symptoms. To our knowledge, this is the first report of powdery mildew on A. frutescens in Italy. G. cichoracearum has been reported on Chrysanthemum frutescens in Switzerland (2). The economic impact of this disease is limited but can easily increase because of the intensive cultivation of this crop. The availability of resistant or partially resistant cultivars will help reduce the impact of this new disease. 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.

scholarly journals Golovinomyces biocellatus on Oregano (Origanum vulgare ‘Compactum’) in Italy

Plant Disease ◽  
2012 ◽  
Vol 96 (3) ◽  
pp. 457-457
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
P. Martini ◽  
L. Repetto ◽  
M. L. Gullino
Keyword(s):  
Powdery Mildew ◽  
Signs And Symptoms ◽  
Its Region ◽  
Pathogenicity Test ◽  
Academic Press ◽  
Conidial Suspension ◽  
Origanum Vulgare ◽  
Leaf Surfaces ◽  
Powdery Mildew Fungi ◽  
Voucher Specimens

Origanum vulgare L., common name oregano, also known as pot marjoram, Lamiaceae family, is grown for its aromatic and medicinal properties and as an ornamental. In particular, O. vulgare ‘Compactum’ is becoming popular as a potted plant. During January 2011, 3-month-old plants grown on a commercial farm located near Albenga (northern Italy) showed signs and symptoms of an unknown powdery mildew. Ninety percent of the plants were affected. The adaxial leaf surfaces were covered with white mycelia and conidia, while the abaxial surfaces were less infected. As the disease progressed, infected leaves turned yellow, wilted, and eventually fell off. Mycelia were also observed on stems. Conidia were hyaline, elliptical, borne single or in short chains (three to four conidia per chain), and measured 37.9 × 19.6 (31.2 to 45.1 × 14.9 to 26.2) μm. Conidiophores were erect with a cylindrical foot cell measuring 81.1 × 9.7 (54.2 to 112.4 × 7.9 to 11.6) μm followed by two to three shorter cells measuring 26.8 × 11.8 (16.6 to 38.1 × 8.5 to 15.3) μm. Fibrosin bodies were absent. Chasmothecia were not observed in the collected samples. The internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1F/ITS4 and sequenced (3) (GenBank Accession No. JN594608). The 560-bp amplicon had 99% homology with the sequence of Golovinomyces biocellatus (GenBank Accession No. AB307675). Pathogenicity was confirmed through inoculation by spraying a conidial suspension (6 × 104 CFU/ml) prepared from diseased leaves onto leaves of healthy O. vulgare ‘Compactum’ plants. Four plants were inoculated while the same number of noninoculated plants served as a control. Plants were maintained in a glasshouse at temperatures ranging from 23 to 28°C. Ten 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. G. biocellatus on O. vulgare has been reported in Switzerland (2) and Argentina (4) and it is present on other plant genera in Italy. In Italy, on the same host, attacks of Erysiphe galeopsis have been previously reported (1). The economic importance of this disease is currently limited due to limited planting of this species. However, in the last years, potted aromatic plants represent a steady increasing crop in Italy. Voucher specimens are available at the Agroinnova Collection, University of Torino. References: (1) K. Amano. Host Range and Geographical Distribution of the Powdery Mildew Fungi. Japan Science Society Press, Tokyo, 1986. (2) A. Bolay. Cryptog. Helv. 20:1, 2005. (3) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990. (4) S. M. Wolcan. J. Plant Patho. 91:501, 2009.

scholarly journals First Report of Powdery Mildew Caused by Golovinomyces cichoracearum on Gerbera (Gerbera jamesonii) in Italy

Plant Disease ◽  
2010 ◽  
Vol 94 (1) ◽  
pp. 130-130 ◽  
Author(s):  
M. Troisi ◽  
D. Bertetti ◽  
A. Garibaldi ◽  
M. L. Gullino
Keyword(s):  
Powdery Mildew ◽  
Signs And Symptoms ◽  
Its Region ◽  
The United States ◽  
Plant Diseases ◽  
Gerbera Jamesonii ◽  
First Report ◽  
Potted Plants ◽  
Golovinomyces Cichoracearum ◽  
Blastn Analysis

Gerbera (Gerbera jamesonii) is one of the top 10 economically important flower crops in Europe as well as the United States. The acreage devoted to this crop continues to increase especially for use in landscape typologies. Abundant flowering from spring until autumn allows the use of this plant to decorate gardens, terraces, and borders. During the summer of 2009, an outbreak of a previously unknown powdery mildew was observed on potted gerbera ‘Mini Yellow’ growing in a private garden in Turin (northern Italy). Adaxial leaf surfaces were covered with white mycelium and conidia, and as the disease progressed, infected leaves turned yellow and died. Conidia were hyaline, ellipsoid, borne in chains (three conidia per chain), and measured 16 to 45 × 10 to 30 μm. Conidiophores measured 109 to 117 × 11 to 13 μm and had a foot cell measuring 72 to 80 × 11 to 12 μm followed by two shorter cells measuring 19 to 29 × 11 to 14 and 20 to 32 × 12 to 14 μm. Fibrosin bodies were absent and chasmothecia were not observed in the collected samples. On the basis of its morphology, the pathogen was identified as Golovinomyces cichoracearum. The internal transcribed spacer (ITS) region of rDNA was amplified with primers ITS1/ITS4 and sequenced. BLASTn analysis of the 548-bp fragment showed an E-value of 0.0 and a percentage homology of 99% with G. cichoracearum isolated from Coreopsis leavenworthii (Accession No. DQ871605) confirming diagnosis inferred by morphological analysis. The nucleotide sequence has been assigned GenBank Accession No. GQ870342. Pathogenicity was confirmed through inoculation by gently pressing diseased leaves onto leaves of three healthy potted plants of Gerbera ‘Mini Yellow’. Three noninoculated plants served as the control. Plants were maintained in a greenhouse at temperatures ranging between 20 and 30°C. Inoculated plants developed signs and symptoms after 8 days, whereas control plants remained healthy. The fungus present on inoculated plants was morphologically identical to that originally observed on diseased plants. To our knowledge, this is the first report of the presence of powdery mildew caused by G. cichoracearum on gerbera in Italy. Specimens are available at the Agroinnova Collection at the University of Torino. Gerbera is also susceptible to different powdery mildews. Powdery mildew of Gerbera jamesonii caused by Sphaerotheca fusca was reported in Italy (4). G. cichoracearum on Gerbera jamesonii was reported in North America (2), Argentina (3), and Switzerland (1). References: (1) A. Bolay. Cryptogam. Helv. 20:1, 2005. (2) M. Daughtrey et al. Page 39 in: Compendium of Flowering Potted Plant Diseases. The American Phytopathological Society, St Paul, MN, 1995. (3) R. Delhey et al. Schlechtendalia 10:79, 2003. (4) F. Zaccaria et al. Ann. Fac. Agrar. Univ. Stud. di Napoli Federico II 34:44, 2000.

scholarly journals First Report of Golovinomyces cichoracearum Causing Powdery Mildew on Zinnia elegans in China

Plant Disease ◽  
2020 ◽  
Author(s):  
Mo Zhu ◽  
Jie Ji ◽  
Xiao Duan ◽  
YongFang Li
Keyword(s):  
Powdery Mildew ◽  
Morphological Characteristics ◽  
Signs And Symptoms ◽  
Its Region ◽  
Zinnia Elegans ◽  
Width Ratio ◽  
Post Inoculation ◽  
First Report ◽  
Golovinomyces Cichoracearum ◽  
Length Width

Zinnia elegans, common zinnia, is an annual plant with highly ornamental values. It is widely planted in many nurseries, city parks, universities and home gardens in China. From August to October 2020, powdery mildew-like signs and symptoms were observed on leaves of Z. elegans growing on the campus of Henan Normal University, Henan Province, China. White powdery colonies in circular- or irregularly shaped-lesions were abundant on both surfaces of leaves and covered up to 95 % of the leaf area. Any infected leaves were chlorotic, deformed or senescence. More than 70 % of the monitored Z. elegans plants showed these signs and symptoms. Conidiophores (n = 20) were 100 to 200 × 9 to 13 μm and composed of foot cells, followed by straight cells and conidia. Mycelial appressoria were single and nipple-shaped. The oval-shaped conidia (n = 30) were 22 to 36 × 12 to 18 μm, with a length/width ratio of 1.4 to 2.7, and produced germ tubes from the polar ends of the spore. No chasmothecia were found. Based on these morphological characteristics, the pathogen was initially identified morphologically as Golovinomyces cichoracearum (Braun and Cook 2012). Structures of the pathogen were scraped from infected leaves and total genomic DNA was isolated using the method previously described by Zhu et al. (2019). The internal transcribed spacer (ITS) region of rDNA was amplified by PCR using the primers ITS1/ITS4 (White et al. 1990) and the amplicon was sequenced by Invitrogen (Shanghai, China). The sequence for the fungus was deposited into GenBank under Accession No. MW029904 and was 99.83 % identical (595/596 bp) to G. cichoracearum on Symphyotrichum novi-belgii (HM769725)(Mørk et al. 2011). To perform pathogenicity analysis, leaf surfaces of five healthy plants were fixed in a settling tower and then inoculated by blowing fungal conidia from mildew-infested leaves using pressurized air. Five non-inoculated plants served as a control. The inoculated and non-inoculated plants were separately maintained in two growth chambers (humidity, 60 %; light/dark, 16 h/8 h; temperature, 18 ℃). Eleven- to twelve-days post-inoculation, powdery mildew signs were conspicuous on inoculated plants, while control plants remained healthy. Similar results were obtained by conducting two repeated pathogenicity assays. Thus, based on the morphological characteristics and molecular analysis, the pathogen was identified and confirmed as G. cichoracearum. This pathogen has been reported on Z. elegans in India, Israel, Jordan, Korea, Nepal, Sri Lanka, Switzerland, and Turkey (Farr and Rossman 2020). To our best knowledge, this is the first report of G. cichoracearum on Z. elegans in China. The sudden outbreak of powdery mildew caused by G. cichoracearum on Z. elegans may adversely impact the plant health and ornamental value in China. Therefore, the confirmation of G. cichoracearum infecting Z. elegans expands the understanding of this pathogen and provides the fundamental knowledge for future powdery mildew control.

scholarly journals Occurrence of Powdery Mildew Caused by Erysiphe buhrii on Dianthus chinensis in Inner Mongolia, China

Plant Disease ◽  
2021 ◽  
Author(s):  
Mo Zhu ◽  
Xiao Duan ◽  
Haoran Guo ◽  
Wei Huang ◽  
Ke Quan ◽  
...  
Keyword(s):  
Powdery Mildew ◽  
Inner Mongolia ◽  
Morphological Characteristics ◽  
Signs And Symptoms ◽  
Its Region ◽  
Width Ratio ◽  
Post Inoculation ◽  
Powdery Mildew Fungus ◽  
Medicinal Uses ◽  
Powdery Mildew Disease

Dianthus chinensis is widely cultivated for ornamental and medicinal use in China (Guo et al. 2017). The plant has been used in traditional Chinese medicine for the treatment of urinary problems such as strangury and diuresis (Han et al. 2015). In June and July 2020, powdery mildew-like signs and symptoms were seen on leaves of D. chinensis cultivated on the campus of Inner Mongolia Agricultural University, Hohhot city, Inner Mongolia Province, China. White powder-like masses occurred in irregular shaped lesions on both leaf surfaces and covered up to 50% of leaf area. Some infected leaves were deformed on their edges and some leaf senescence occurred. More than 40 % of plants (n = 180) exhibited these signs and symptoms. Conidiophores (n = 50) of the suspect fungus were unbranched and measured 70 to 140 µm long × 6 to 10 µm wide and had foot cells that were 25 to 48 µm long. Conidia (n = 50) were produced singly, elliptical to cylindrical shaped, 30 to 45 µm long × 12 to 19 µm wide, with length/width ratio of 2.0 to 3.2, and lacked fibrosin bodies. No chasmothecia were found. Based on these morphological characteristics, the fungus was tentatively identified as an Erysiphe sp. (Braun and Cook 2012). Fungal structures were isolated from diseased leaves and genomic DNA of the pathogen extracted utilizing the method described by Zhu et al. (2019). The internal transcribed spacer (ITS) region was amplified by PCR employing the primers PMITS1/PMITS2 (Cunnington et al. 2003) and the amplicon sequenced by Invitrogen (Shanghai, China). The sequence for the powdery mildew fungus (deposited into GenBank under Accession No. MW144997) showed 100 % identity (558/558 bp) with E. buhrii (Accession No. LC009898) that was reported on Dianthus sp. in Japan (Takamatsu et al. 2015). Pathogenicity tests were done by collecting fungal conidia from infected D. chinensis leaves and brushing them onto leaves of four healthy plants. Four uninoculated plants served as controls. Inoculated and uninoculated plants were placed in separate growth chambers maintained at 19 ℃, 65 % humidity, with a 16 h/8 h light/dark period. Nine-days post-inoculation, powdery mildew disease signs appeared on inoculated plants, whereas control plants remained asymptomatic. The same results were obtained for two repeated pathogenicity experiments. The powdery mildew fungus was identified and confirmed as E. buhrii based on morphological and molecular analysis. An Oidium sp. causing powdery mildew on D. chinensis previously was reported in Xinjiang Province, China (Zheng and Yu 1987). This, to the best of our knowledge, is the first report of powdery mildew caused by E. buhrii on D. chinensis in China (Farr and Rossman 2020). The sudden occurrence of this destructive powdery mildew disease on D. chinensis may adversely affect the health, ornamental value and medicinal uses of the plant in China. Identifying the cause of the disease will support efforts for its future control and management.

scholarly journals Powdery Mildew Caused by Golovinomyces biocellatus on Spearmint (Mentha spicata) in Italy

Plant Disease ◽  
2010 ◽  
Vol 94 (9) ◽  
pp. 1171-1171 ◽  
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
P. Pensa ◽  
M. L. Gullino
Keyword(s):  
United States ◽  
Powdery Mildew ◽  
Signs And Symptoms ◽  
Its Region ◽  
The United States ◽  
Pathogenicity Test ◽  
Aromatic Plants ◽  
Mentha Spicata ◽  
Leaf Surfaces ◽  
Voucher Specimens

Spearmint (Mentha spicata) is grown for its aromatic and carminative oil and as an ornamental. During the fall of 2009, 4-month-old plants grown on a commercial farm located near Albenga (northern Italy) showed signs and symptoms of an unknown powdery mildew. The adaxial leaf surfaces were covered with white mycelia and conidia, while the abaxial surfaces were less infected. As the disease progressed, infected leaves turned yellow and wilted. Mycelia were also observed on stems. Conidia were hyaline, elliptical to doliform, borne in short chains (two to three conidia per chain), and measured 35 × 21 μm (30 to 43 × 18 to 26 μm). Conidiophores measured 86 × 11 μm (76 to 97 × 9 to 13 μm) followed by one to three shorter cells, measuring, respectively, 22 × 11 μm (13 to 28 × 9 to 15 μm). 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 (1) (GenBank Accession No. HM053470). The 567-bp amplicon had 100% homology with the sequence of Golovinomyces biocellatus (GenBank Accession No. AB307675). Pathogenicity was confirmed through inoculation by gently pressing diseased leaves onto leaves of healthy M. spicata plants. Three plants were inoculated, while the same number of noninoculated plants served as a control. Plants were maintained at temperatures from 18 to 25°C. Twelve 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. G. biocellatus has been reported on Mentha spp. in Australia (3) and the United States (4) and the pathogen is present on other plant genera in Italy. A similar powdery mildew of M. spicata was attributed to Erysiphe orontii in the United States (2). The economic importance of this disease is currently limited in Italy because of the limited planting of this host, but potted aromatic plants represent a steadily increasing crop in Italy. 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) S. T. Koike and G. S. Saenz. Plant Dis. 83:399, 1999. (3) J. R. Liberato and J. H. Cunnington. Australas. Plant Dis. Notes 2:83, 2007. (4) D. B. Marcum et al. Plant Dis. 94:276, 2010.

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

Plant Disease ◽  
2008 ◽  
Vol 92 (6) ◽  
pp. 975-975 ◽  
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.

scholarly journals Podosphaera sp. on Euphorbia susannae and E. inermis in Italy

Plant Disease ◽  
2012 ◽  
Vol 96 (12) ◽  
pp. 1824-1824
Author(s):  
A. Garibaldi ◽  
D. Bertetti ◽  
P. Pensa ◽  
A. Poli ◽  
M. L. Gullino
Keyword(s):  
Powdery Mildew ◽  
Democratic Republic ◽  
Morphological Characteristics ◽  
Its Region ◽  
Northern Italy ◽  
Pathogenicity Test ◽  
Academic Press ◽  
Potted Plants ◽  
Powdery Mildews ◽  
White Mycelium

Euphorbia susannae (common name Suzane's spurge) and E. inermis (Euphorbiaceae family) are grown in pots and commercialized in northern Italy. In March 2012, plants of these species grown on the same commercial farm showed signs of powdery mildew. On E. susannae, apexes of stems were covered with white mycelia and conidia, with the ultimate development of necrosis on symptomatic tissues more interested by the disease. Of 5,000 plants, 5% were affected. Conidia were hyaline, elliptical, borne in short chains (two to three conidia per chain), and 27.7 (24.4 to 30.6) μm long and 16.1 (13.6 to 19.1) μm wide. Conidiophores were erect, with a foot cell straight or slightly flexuous, 82.8 (52.7 to 117.1) μm long and 10.0 (9.2 to 11.2) μm wide, followed by two to three shorter cells 19.8 (14.7 to 28.9) μm long and 10.7 (8.7 to 13.0) μm wide. On E. inermis, a white mycelium covered the stems starting from the apexes, causing yellowing and necrosis on leaves finally killing infected tissues. Of 500 plants, 80% were affected. Conidia were 33.2 (25.7 to 42.0) μm long and 17.3 (12.6 to 21.6) μm wide. Conidiophores were erect, with a foot cell straight or slightly flexuous, 96.7 (67.0 to 138.6) μm long and 9.5 (7.7 to 11.7) μm wide, followed by two to three shorter cells 26.3 (17.5 to 42.2) μm long and 11.8 (8.3 to 16.2) μm wide. Fibrosin bodies were present on both hosts, while chasmothecia were not observed in samples from either host. The internal transcribed spacer (ITS) region of rDNA of samples of mycelium and conidia collected from the two hosts was amplified using the primers ITS1-ITS4 (3) and directly sequenced (GenBank Accession Nos. JX179221 and JX179219 for E. susannae and E. inermis, respectively). By performing BLAST analysis, the 692-bp amplicon from E. susannae and the 541-bp amplicon from E. inermis showed 100% homology with several sequences of Podosphaera spp. On the basis of morphological characteristics of the imperfect state and the ITS analysis, the causal agent of powdery mildew on E. susannae and E. inermis was identified as Podosphaera sp. Pathogenicity was confirmed by gently brushing healthy 20-month-old potted plants of E. susannae and E. inermis with mycelia and conidia from diseased plants. Four plants/treatment/species were used. Non-inoculated plants belonging to the two species served as control. Plants were maintained in a glasshouse at temperatures ranging from 18 to 25°C and relative humidity from 65 to 80%. About 20 days after inoculation, typical symptoms of powdery mildew developed on inoculated plants. The fungus observed on inoculated plants was morphologically identical to the original isolate. Non-inoculated plants did not exhibit symptoms. The pathogenicity test was performed in duplicate. Several agents of powdery mildew have been reported on Euphorbia spp. Among others, Podosphaera euphorbiae was reported on numerous Euphorbiaceae (1), P. euphorbiae-hirtae was observed on E. hirta (1) and P. euphorbiae-helioscopiae on E. pekinensis (2). To our knowledge, this is the first report of Podosphaera sp. on E. susannae and E. inermis in Italy. This disease is not presently of economic importance. Specimens are available at the Agroinnova Collection. References: (1) U. Braun. A Monograph of the Erysiphales (Powdery Mildews). J. Cramer, Berlin-Stuttgard, German Democratic Republic, 1987. (2) S. Y. Liu. Plant Dis. 95:1314, 2011. (3) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, 1990.

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