First Report of Euoidium longipes, a New Powdery Mildew Fungus on Tamarillo (Solanum betaceum) in New Zealand

California poppy is an annual species grown widely in the Pacific Northwest. Once established, populations are self-seeding and require little care. During an ongoing study of Erysiphales, a powdery mildew fungus was collected repeatedly on this species in Seattle, WA. The fungus was determined to be Erysiphe cruciferarum Opiz ex Junell, a species not reported previously on this host in North America. This report documents the occurrence of the disease and provides information on the morphology and identification of the causal agent. Accepted for publication 8 November 2006. Published 13 December 2006.

Download Full-text

First Report of Powdery Mildew Caused by Podosphaera xanthii on Cuphea hyssopifolia (Lythraceae) in Mainland China

Plant Disease ◽

10.1094/pdis-03-21-0545-pdn ◽

2021 ◽

Author(s):

Irum Mukhtar ◽

Ruiting Li ◽

IBATSAM KHOKHAR ◽

Ruanni Chen ◽

Yunying Cheng ◽

...

Keyword(s):

Powdery Mildew ◽

Disease Incidence ◽

Large Subunit ◽

Mainland China ◽

Lsu Rdna ◽

Podosphaera Xanthii ◽

Powdery Mildew Fungus ◽

Potential Threat ◽

First Report ◽

Plant Pathol

Cuphea hyssopifolia (Mexican heather) is a popular evergreen perennial shrub used for ornamental and medicinal purposes. Due to its high ornamental value, it is often used as a ground cover in parks and gardens in China. During February and March 2019 & 2020, powdery mildew was observed on C. hyssopifolia in the districts of Minhou and Jinshan of Fuzhou, China. Disease incidence was 70% but of low severity with only a few older leaves showing yellowing and wilting. Sparse irregular patches of white superficial powdery mildew observed on both sides of mature and young leaves. The powdery mildew fungal appressoria that occurred on epigenous hyphae, were indistinct to nipple-shaped, hyaline, and smooth. Conidiophores were erect, smooth, 80 to 210 × 10 to 12 µm, and produced two to eight crenate-shaped conidia in chains. Foot-cells of conidiophores were straight, cylindric, and 30 to 65 × 10 to12 µm. Conidia were hyaline, smooth, ellipsoid-ovoid to barrel-shaped, 25 to 38 × 16 to 20 µm with distinct fibrosin bodies. Germ tubes were simple to forked and produced from the lateral position of the germinating conidia. No chasmothecia were observed on the surface of infected leaves. Based on the morphology of the imperfect state, the powdery mildew fungus was identified as Podosphaera xanthii (Castagne) U. Braun & N. Shishkoff (Braun and Cook 2012). To confirm fungal identification, total DNA was extracted (Mukhtar et al., 2018) directly from epiphytic mycelia on infected leaves collected from both districts. Internal transcribed spacer (ITS) regions and the partial large subunit (LSU) rDNA were amplified using primers ITS1/ITS4 and LSU1/LSU2 (Scholin et al. 1994, White et al. 1990), respectively. The sequences were deposited in GenBank (ITS: MW692364, MW692365; LSU: MW699924, MW699925). The ITS and LSU sequences were 99 to 100 % identical to those of P. xanthii in GenBank, (ITS: MT568609, MT472035, MT250855, and AB462800; LSU: AB936276, JX896687, AB936277, and AB936274). Koch’s postulates were completed by gently pressing diseased leaves onto leaves of five healthy potted C. hyssopifolia plants that were held in a greenhouse at 24 to 30°C without humidity control. Five non-inoculated plants served as controls. Inoculated plants developed symptoms after 6 to 10 days, whereas the controls remained symptomless. The morphology of the fungus on the inoculated leaves was identical to that observed on the originally diseased leaves. Previously, Podosphaera sp. has been reported on C. rosea in the United Kingdom (Beales & Cook 2008) and P. xanthii on C. hyssopifolia in Taiwan (Yeh et al. 2021). To our knowledge, this is the first report of powdery mildew caused by P. xanthii on C. hyssopifolia in mainland China. Our field observations suggest that the P. xanthii infections would be a potential threat to the health of C. hyssopifolia in China. References: Beales, P. A., and Cook, R. T. A. 2008. Plant Pathol. 57:778. Braun, U., Cook, R. T. A. 2012. The Taxonomic Manual of the Erysiphales (Powdery Mildews). CBS Biodiversity Series 11: CBS. Utrecht, The Netherlands. Mukhtar, I., et al. 2018. Sydowia.70:155. Scholin, C. A., et al. 1994. J. Phycol. 30:999. White, T. J., et al. 1990. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA. Yeh, Y. W., et al. 2021. Trop. Plant Pathol. 46:44.

Download Full-text

First Report of Powdery Mildew on Pyrus calleryana Caused by Podosphaera leucotricha

Plant Disease ◽

10.1094/pdis-92-1-0176b ◽

2008 ◽

Vol 92 (1) ◽

pp. 176-176 ◽

Cited By ~ 1

Author(s):

L. Vajna ◽

L. Kiss

Keyword(s):

Powdery Mildew ◽

Urban Areas ◽

Its Sequence ◽

Podosphaera Leucotricha ◽

Powdery Mildew Fungus ◽

First Report ◽

Host Genus ◽

Pyrus Calleryana ◽

Single Leaf ◽

Leaf Surfaces

Callery pear (Pyrus calleryana Decne.) is native to Asia and its varieties are planted as ornamentals in urban areas worldwide. It is also used as a source of resistance to fireblight in some breeding programs. In April 2007, symptoms of powdery mildew infection were observed on the foliage of almost every P. calleryana cv. Chanticleer tree planted along a 1.5-km road in Budapest, Hungary. These trees were planted 5 to 6 years ago and were the first callery pears used as ornamentals in Hungary. Powdery mildew infections were also detected on P. calleryana trees planted in other parts of the city. White powdery mildew mycelium appeared on the lower and sometimes upper leaf surfaces, especially on young shoots, and caused chlorotic spots on the upper leaf surfaces and severe distortions of leaves. The spread of the infection was monitored between April and August of 2007 in several sample sites. More than 100 trees that were examined became heavily infected by May 2007. Powdery mildew conidiophores were typical of the genus Oidium subgen. Fibroidium, the anamorph of the teleomorph genus Podosphaera (2). Conidia developed in chains, contained fibrosin bodies, germinated at one of their ends with germ tubes terminating in unlobed appressoria, and measured 16 to 27 × 10 to 15 μm. Hyphal appressoria were nipple shaped or inconspicuous. The teleomorph was not found. To precisely identify the pathogen, DNA was extracted from conidia collected with a sterile brush from a single leaf using a Qiagen DNeasy Plant Kit (Hilden, Germany), and the internal transcribed spacer (ITS) sequence of the ribosomal DNA was amplified and determined as described by Szentiványi et al. (3). The ITS sequence, deposited in GenBank under Accession No. EU148597, was identical to those determined in Podosphaera leucotricha (Ell. & Ev.) Salmon collected from apple in Australia (GenBank Accession No. AF073353) and Canada (GenBank Accession No. AY157844) and also from pear in Canada (GenBank Accession No. AY157845). Thus, the pathogen was identified as Podosphaera leucotricha on the basis of the host genus, morphology of the anamorph, and ITS sequence. Specimens were deposited under Accession No. BPI878262 at the U.S. National Fungus Collection. To our knowledge, Podosphaera leucotricha has not been reported on P. calleryana in any parts of the world so far. An Oidium sp. infecting this plant in Australia was listed by Amano (1), but the exact identity of that fungus is not known. Thus, this is the first report of an identified powdery mildew fungus on P. calleryana. References: (1) K. Amano. Host Range and Geographical Distribution of the Powdery Mildew Fungi. Japan Scientific Societies Press, Tokyo, 1986. (2) U. Braun et al. Pages 13-55 in: The Powdery Mildews: A Comprehensive Treatise. R. R Bélanger et al., eds. American Phytopathological Society, St Paul, MN, 2002. (3) O. Szentiványi et al. Mycol. Res. 109:429, 2005.

Download Full-text

First Report of Powdery Mildew Caused by Podosphaera fusca on Herba eupatorii in China

Plant Disease ◽

10.1094/pdis-11-12-1090-pdn ◽

2013 ◽

Vol 97 (7) ◽

pp. 995-995 ◽

Cited By ~ 2

Author(s):

J. P. Ding ◽

D. L. Pei ◽

Q. C. Zhang ◽

Q. C. Hong ◽

Y. Z. Ren ◽

...

Keyword(s):

Powdery Mildew ◽

Its Sequence ◽

Distilled Water ◽

Conidial Suspension ◽

Powdery Mildew Fungus ◽

First Report ◽

Its Sequence Analysis ◽

Leaf Surfaces ◽

Asteraceae Family ◽

Podosphaera Fusca

Herba eupatorii, one of the most important Chinese medicinal herbs, belongs to the Asteraceae family. In June 2012, a previously unknown disease, tentatively identified as powdery mildew, was observed on H. eupatorii growing in Shangqiu, in eastern Henan Province, China. Symptoms began as white mycelium partially covering upper leaf surfaces; as the disease progressed, it spread to cover entire leaf surfaces. The infected leaves became yellow and necrotic at advanced stages of infection. Specimens consisting of infected leaves were maintained at the Plant-Microbe Interaction Laboratory at Shangqiu Normal University. Microscopic observations of the morphology of the fungus revealed oval primary conidia measuring 18 to 27 × 15 to 22 μm. A long unbranched germ tube that germinated laterally from the ends of conidia was observed in some samples. Conidiophores were cylindrical, simple unbranched, and composed of a basal cell with a swollen base and three to six barrel-shaped conidia formed in chains, measuring 112 to 180 × 9 to 12 μm. Mycelial appressoria were nipple-shaped. Chasmothecia were not observed in the collected samples. To verify the identity of the fungus, the internal transcribed spacer (ITS) rDNA was amplified with ITS1 and ITS4 primers (3) and sequenced. The sequences were deposited as GenBank Accession No. JX546297. Comparison with sequences in the GenBank database revealed that the ITS sequence was 100% homologous with the sequence of Podosphaera fusca on Calendula officinalis (AB525914) (2) and Syneilesis palmata (AB040349) (1). The ITS sequence analysis verified that the causal agent was P. fusca, which is reported to be a cosmopolitan powdery mildew fungus, parasitic on numerous plant species in the Asteraceae family. Koch's postulates were completed by inoculating healthy H. eupatorii plants with a conidial suspension (prepared in distilled water) of 105 conidia/ml collected from infected plants. Five plants were sprayed until the suspension ran off the leaves, while five additional plants were sprayed with distilled water as a control. Plants were maintained in a climate cell under the following conditions: day, 24°C, 16 h; night, 20°C, 8 h; 85% humidity. After 10 days, inoculated plants developed symptoms similar to those observed in the field, whereas control plants remained healthy. Further examination showed that the inoculated plants were infected by P. fusca. To our knowledge, this is the first report of P. fusca affecting H. eupatorii in China. Because there are no fungicides labeled for use on this plant, the appearance of powdery mildew caused by P. fusca could result in substantial production loss of H. eupatorii. References: (1) T. Hirata et al. Can. J. Bot. 78:1521, 2000. (2) S. Takamatsu et al. Persoonia 24:38, 2010. (3) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, CA, 1990.

Download Full-text

First Report of Powdery Mildew Caused by Erysiphe arcuata on Lanceleaf Coreopsis (Coreopsis lanceolata) in Korea

Plant Disease ◽

10.1094/pdis-08-12-0754-pdn ◽

2012 ◽

Vol 96 (12) ◽

pp. 1827-1827 ◽

Cited By ~ 1

Author(s):

H. B. Lee

Keyword(s):

Powdery Mildew ◽

Invasive Plant ◽

Signs And Symptoms ◽

Morphological Data ◽

Powdery Mildew Fungus ◽

First Report ◽

Rdna Its ◽

The World ◽

The Usa ◽

Cut Foliage

Lanceleaf coreopsis (Coreopsis lanceolata L.) is a plant species of the genus Coreopsis in Asteraceae native to the USA. This plant is a bushy perennial species with finely cut foliage and showy round flowers and is increasing as plants used in landscaping in the world. The invasive plant is also planted very commonly along roadsides in Korea. In late October 2011 and August 2012, signs and symptoms of a powdery mildew disease were observed on lanceleaf coreopsis in several land areas near Gwangju-river, Gwangju, Korea. Symptoms included typical white superficial mycelia. The conidia of the powdery mildew fungus occurred on adaxial and abaxial surfaces. Chasmothecia were not observed. Single conidia formed terminally on conidiophores. Conidial morphology was subcylindrical to oblong. Dimension of conidia was 23.6 to 41.4 (avg. 35.1) μm long × 11.3 to 18.2 (avg. 14.8) μm wide. Conidiophores were composed of five to six (up to seven) cells, ranged from 45.7 to 131.2 (avg. 98.1) μm long × 8.2 to 11.1 (avg. 8.3) μm wide with foot-cells straight to slightly flexuous. Oidium anamorph of this fungus matched that of E. arcuata U. Braun, Heluta and S. Takam. described by Pastircakova et al. (3). From extracted genomic DNA, the rDNA ITS was amplified with ITS1F (5′-CTTGGTCATTTAGAGGAAGT-3′) and LR5F (5′-GCTATCCTGAGGGAAAC-3′) primer set. The rDNA ITS homology of the fungus (EML-CDPW1, GenBank Accession No. JX485650) showed 100% (590/590) identity value with E. arcuata (GenBank Accession No. AB252459). The identification of the fungus as E. arcuata was based on morphological data combined with the results of sequence analysis. Until recently, E. arcuata has been known to widespread on Carpinus species of the family Betulaceae including European hornbeam (C. betulus L.) and Chonowski's hornbeam (C. tschonoskii Maxim.) in Asia and Europe since Braun et al. first reported it as a new species in 2006 (1). In Korea, Podosphaera fusca (= Sphaerotheca fusca) and P. fuliginea (= S. fuliginea) were reported to cause powdery mildews on Coreopsis lanceolata. E. cichoracearum (= Golovinomyces cichoracearum), Leveillula taurica, P. fusca (= S. fusca), and Oidium spp. have been reported on Coreopsis spp. in the world (3). To our knowledge, this is the first report of powdery mildew caused by Oidium anamorph of E. arcuata on lanceleaf coreopsis (C. lanceolata) in Korea or elsewhere in the world. References: (1) U. Braun et al. Mycol. Prog. 5:139, 2006. (2) D. F. Farr and A. Y. Rossman. Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA. http://nt.ars-grin.gov/fungaldatabases/ , 2012. (3) K. Pastircakova et al. J. Phytopathol. 156:597, 2008.

Download Full-text

First Report of Powdery Mildew Caused by Podosphaera xanthii on Salvia farinacea in Korea

Plant Disease ◽

10.1094/pdis-07-21-1427-pdn ◽

2021 ◽

Author(s):

In-Young Choi ◽

Ho-Jong Ju ◽

Kui-Jae Lee ◽

Hyeon-Dong Shin

Keyword(s):

Powdery Mildew ◽

Large Subunit ◽

Pcr Amplification ◽

Echinacea Purpurea ◽

The United States ◽

Infected Leaf ◽

Podosphaera Xanthii ◽

Powdery Mildew Fungus ◽

First Report ◽

Perennial Plant

Salvia farinacea Benth. (Lamiaceae) is an herbaceous perennial plant, native to Mexico and southern parts of the United States. This plant is cultivated worldwide for its ornamental value. In November 2019, hundreds of S. farinacea ‘Blue Bedder” grown in a flower garden in Jeju (33°30'57"N 126°32'50"E), Korea have been found to be infected with a powdery mildew fungus. The disease severity was estimated to be 100%. Likewise in October 2020, a similar situation with this plant was also observed in a flower garden in Seoul (37°35'19"N 127°01'07"E), Korea. Leaves, stems and inflorescence of plants were covered by white, thin mycelial felt, bearing an abundance of conidiophores and conidia. Eventually, infected plants lose their ornamental value. Two voucher specimens have been deposited in the Korea University Herbarium (KUS-F31478 and F32164). Fresh materials were examined. Hyphal appressoria were nipple-shaped, but rarely found. Conidiophores (n = 30) were straight, 95 to 160 × 10 to 12 μm and produced 2 to 7 immature conidia in chains with a crenate outline. Foot-cells were cylindric and 36 to 60 μm long. Conidia (n = 30) were ellipsoid-ovoid to barrel-shaped, 32 to 38 × 18 to 24 μm, and contained conspicuous fibrosin bodies. Dark brown chasmothecia were found partly embedded in the mycelial felt on leaves, mostly hypophyllous, spherical, and 82 to 100 µm diameter, with a single ascus in each. Appendages were few, mycelioid, 1- to 4-septate, brown near the base when mature, but paler above. Asci were broadly ellipsoid to subglobose, 56 to 68 × 50 to 62 μm, sessile and 8-spored. Ascospores were colorless, oval to subglobose, and 14 to 18 × 12 to 15 µm. These characteristics were consistent with those of Podosphaera xanthii (Castagne) U. Braun & Shishkoff (Braun and Cook 2012). For further confirmation, genomic DNA was extracted from chasmothecia from KUS-F31478 and F32164. PCR amplification was performed using the primer pair ITS1F/PM6 for internal transcribed spacer (ITS) and PM3/TW14 for the large subunit (LSU) of the rDNA (Takamatsu and Kano 2001). Obtained sequences were deposited to the GenBank under the accession numbers MZ359847 and MZ359859 for ITS, MZ359858 and MZ359861 for LSU. For ITS regions 99.80-100% similarity was found with sequences MT131256 (Salvia farinacea), MT131254 (Mazus pumilus) and MT131252 (Erigeron bellioides) of P. xanthii, whereas it was 99.90% with sequences of this fungus on Echinacea purpurea (MT826247 and MT826245) for 28S rDNA gene. Pathogenicity tests were carried out by touching an infected leaf onto healthy leaves of disease-free 30 days old potted ‘Blue Bedder’ using replication of five plants, with five non-inoculated plants used as controls. The typical signs of powdery mildew started to develop on the inoculated leaves in 7 to 10 days, and microscopic examination revealed the morphological identity with the fungus observed from the field. All non-inoculated control plants remained symptomless. Hitherto Golovinomyces powdery mildews on Salvia spp. were reported globally (Farr and Rossman 2021). However, Podosphaera elsholtziae on Salvia sp. and P. xanthii on S. farinacea were reported from China and Taiwan (Zheng and Yu 1987, Yeh et al. 2021). To our knowledge, this is the first report of P. xanthii on S. farinacea in Korea. The occurrence of Podosphaera powdery mildew on S. farinacea could pose a serious threat to the beauty of this plant, causing premature senescence of young leaves and gray to purplish discoloration of the leaves.

Download Full-text

First Report of Powdery Mildew Caused by Podosphaera macularis on Hemp in Oregon

Plant Health Progress ◽

10.1094/php-04-21-0071-br ◽

2021 ◽

Author(s):

Taylor Bates ◽

Mary Holzberger-Block ◽

Michele Wiseman ◽

Andrea Garfinkel ◽

David Gent ◽

...

Keyword(s):

Powdery Mildew ◽

Cannabis Sativa ◽

Natural Conditions ◽

Powdery Mildew Fungus ◽

Management Implications ◽

First Report ◽

Podosphaera Macularis

In Oregon, hemp (Cannabis sativa) production has increased substantially after cultivation was legalized in the 2014 and 2018 Farm Bills. Typically, hemp species are affected by powdery mildew caused by Golovinomyces species. This paper reports on hop powdery mildew caused by Podosphaeria macularis, found colonizing hemp in natural conditions. The occurrence of the hop powdery mildew fungus on hemp may have management implications for both the hemp and hop industry.

Download Full-text

First Report of Powdery Mildew on Dollar-plant (Crassula ovata) Caused by an Oidium sp.

Plant Disease ◽

10.1094/pdis.1999.83.2.199c ◽

1999 ◽

Vol 83 (2) ◽

pp. 199-199 ◽

Cited By ~ 2

Author(s):

L. Kiss

Keyword(s):

Powdery Mildew ◽

The United States ◽

Diseased Plant ◽

Powdery Mildew Fungus ◽

History Museum ◽

First Report ◽

Powdery Mildews ◽

Leaf Surfaces ◽

Hungarian Natural History Museum ◽

Germ Tubes

Dollar-plant (Crassula ovata) is a perennial, succulent ornamental grown worldwide. In 1998, powdery mildew colonies were observed on the adaxial leaf surfaces of a 4-year-old specimen maintained outdoors. Symptoms included necrosis of the infected tissues and defoliation 2 months after the appearance of the first colonies. Conidia were produced in chains on unbranched conidiophores. Hyphal appressoria were lobed to multi-lobed, mostly opposite or spread. Conidia were ellipsoid to cylindrical, measured 34 to 48 μm × 17 to 26 μm, and contained no fibrosin bodies. On water agar, conidia produced a single germ tube from the end of the conidium. Germ tubes were either very short with lobed appressoria, or were two to three times longer than conidia, and terminated in lobed or unlobed appressoria. Cleistothecia were not produced. The pathogen was identified as an Oidium sp. belonging to the genus Erysiphe sect. Galeopsidis (1). To confirm pathogenicity, small, potted C. ovata plants were placed near the diseased plant in the laboratory. After 2 weeks, powdery mildew appeared on the small plants, and the pathogen was morphologically identical to the original fungus. This is the first report of a powdery mildew fungus on C. ovata, and it is different from both species of the Erysiphaceae identified on other Crassula spp. (1,2). Infected C. ovata leaves were deposited at the Department of Botany of the Hungarian Natural History Museum in Budapest under the accession number BP 91732. References: (1) U. Braun. 1995. The Powdery Mildews (Erysiphales) of Europe. Gustav Fischer Verlag, Jena. (2) D. F. Farr et al. 1989. Fungi on Plants and Plant Products in the United States. American Phytopathological Society, St. Paul, MN.

Download Full-text

First Report of Powdery Mildew of Scabiosa columbaria (Dove Pincushions) Caused by Erysiphe knautiae in North America

Plant Health Progress ◽

10.1094/php-2005-1024-01-br ◽

2005 ◽

Vol 6 (1) ◽

pp. 24

Author(s):

Dean A. Glawe ◽

Gary G. Grove

Keyword(s):

North America ◽

Powdery Mildew ◽

Host Species ◽

Causal Agent ◽

Perennial Species ◽

Powdery Mildew Fungus ◽

Diagnostic Features ◽

First Report ◽

Landscape Plant

Scabiosa columbaria L. (dove pincushions) is a perennial species introduced into North America, where it is grown as an ornamental landscape plant. Little information is available on pathogens attacking it in North America. Recently, the authors encountered a powdery mildew fungus on this host species in Washington and determined it to be Erysiphe knautiae Duby. This report describes the disease as well as diagnostic features and taxonomy of the causal agent. Accepted for publication 11 October 2005. Published 24 October 2005.

Download Full-text

First Report of Powdery Mildew of Convolvulus arvensis (Field Bindweed) Caused by Erysiphe convolvuli var. convolvuli in North America

Plant Health Progress ◽

10.1094/php-2003-1021-01-hn ◽

2003 ◽

Vol 4 (1) ◽

pp. 31

Author(s):

Dean A. Glawe ◽

Gwenyth E. Windom ◽

Gary G. Grove ◽

Jennifer S. Falacy

Keyword(s):

North America ◽

Powdery Mildew ◽

Pacific Northwest ◽

Morphological Features ◽

Convolvulus Arvensis ◽

Powdery Mildew Fungus ◽

First Report ◽

The Pacific ◽

Field Bindweed ◽

Noxious Weed

Field bindweed (Convolvulus arvensis L.) is widespread in the Pacific Northwest where it is considered a noxious weed. During 2002, collections of a powdery mildew fungus attacking C. arvensis were made from Pierce, Spokane, Whitman, and Yakima counties, WA. Based on morphological features we determined the fungus to be Erysiphe convolvuli. Accepted for publication 22 September 2003. Published 21 October 2003.

Download Full-text