scholarly journals First Report of Powdery Mildew on Potato Caused by Golovinomyces cichoracearum in California

Plant Disease ◽  
2004 ◽  
Vol 88 (3) ◽  
pp. 309-309 ◽  
Author(s):  
M. K. Romberg ◽  
J. J. Nuñez ◽  
J. J. Farrar
Keyword(s):  
New York ◽  
Powdery Mildew ◽  
Standard Error ◽  
Disease Spread ◽  
Disease Symptoms ◽  
First Report ◽  
Erysiphe Cichoracearum ◽  
Golovinomyces Cichoracearum ◽  
Plastic Bag ◽  
Field Report

In October 2003, potato plants in three fields (cv. Desiree, Satina, Midas, and Mondial) in Lancaster, California exhibited symptoms and signs of powdery mildew. Disease symptoms were most severe on cvs. Desiree and Santina. Disease expression was greater along sprinkler lines and in localized areas from which the disease spread to surrounding plants. Severely affected plants began collapsing just prior to water cutoff. Early symptoms comprise small dark areas on the adaxial surface of leaves, along the veins, and at the petioles. Dark lesions consisting of mycelia and conidiophores were also visible on the main stems of affected plants. As the disease progressed, leaves were covered by a gray powdery fungal mass, and older leaves became necrotic. Conidial chains arising from the hyaline, epiphytic mycelia consisted of two to eight conidia. The cylindric to doliform conidia measured 16.8 to 22.8 μm wide (mean = 19.2, standard error = 0.36, N = 30) × 28.8 to 45.6 μm long (mean = 32.4, standard error = 0.75, N = 30). No cleistothecia were observed. Identification of the causal agent as Golovinomyces cichoracearum (synonyms G. orontii and Erysiphe cichoracearum) based on morphology was confirmed by internal transcribed spacer (ITS)-polymerase chain reaction (PCR). Conidia were washed off the affected leaves, concentrated by filtration and centrifugation, and sonicated to release genomic DNA. PCR was performed on the sonicated conidia with primers ITS4 and ITS5 (2), and the resulting amplicon was purified and sequenced. BLAST analysis of the ITS sequence revealed a 99% homology to E. cichoracearum from an Ambrosia sp. (GenBank Accession No. AF011292). Pathogenicity was confirmed on potato seedlings cv. Red La Soda. Inoculations were performed twice on six plants (three pots) each time. A sterile brush was used to transfer conidia from the affected leaves to seedlings consisting of two to three fully expanded leaves. A plastic bag was placed around each pot containing two seedlings for 1 to 2 days and then removed. Noninoculated controls were stroked with a sterile brush, placed in a plastic bag for 1 to 2 days, and kept in the greenhouse on a separate bench. Two control plants were included for each inoculation. Plants were maintained in a greenhouse at approximately 25 to 28°C and 40 to 60% relative humidity. After 7 days, dark spots were visible on the leaves of all inoculated plants, and conidiophores with conidia identical to those of the isolate used as the inoculum source were apparent after 10 days. The controls showed no disease symptoms or signs. To our knowledge, this is the first report of powdery mildew caused by G. cichoracearum on potato in California. The first field report of the disease was from Washington in 1950 (1), with subsequent reports from Utah and Ohio. References: (1) J. D. Menzies. Plant Dis. Rep. 34:140, 1950. (2) T. J. White et al. PCR Protocols. Academic Press, New York, 1990.

scholarly journals First Report of Powdery Mildew on Ruth's Golden Aster (Pityopsis ruthii) Caused by Golovinomyces cichoracearum (Erysiphe cichoracearum)

Plant Disease ◽  
2011 ◽  
Vol 95 (7) ◽  
pp. 879-879
Author(s):  
R. N. Trigiano ◽  
A. J. Dattilo ◽  
P. A. Wadl
Keyword(s):  
New York ◽  
Powdery Mildew ◽  
Online Publication ◽  
Signs And Symptoms ◽  
Plant Health ◽  
First Report ◽  
Erysiphe Cichoracearum ◽  
Golovinomyces Cichoracearum ◽  
Health Progress

Ruth's golden aster (Pityopsis ruthii (Small) Small: Asteraceae) is an endangered, herbaceous perennial that occurs only at a few sites along small reaches of the Hiwassee and Ocoee rivers in Polk County, Tennessee. As part of a planned restoration program, Ruth's golden aster has been micropropagated in vitro and acclimatized to greenhouse conditions. In February 2011, several established plants in a greenhouse in Knoxville, TN exhibited signs and symptoms of powdery mildew including growth of white mycelium and conidiophores on the adaxial surface of leaves and slight curling upward of leaf margins. Mycelium was superficial and nipple-shaped appressoria were present. Mycelia, conidiophores, and conidia were removed from several leaves, mounted in water, and examined microscopically. Cylindrical to ovoid conidia (n = 100) lacking fibrosin bodies were borne in chains and had a mean length of 32.0 μm (19.2 to 38.7 μm) and width of 14.9 μm (6.3 to 21.2 μm). The description and dimension of the conidia agreed well with that provided for Golovinomyces cichoracearum (Erysiphe cichoracearum) reported on Coreopsis spp. (1,3) and Cirsium arvense (creeping thistle) (2). The teleomorph was not observed. Total genomic DNA was extracted from infected leaves, amplified with ITS1 and ITS4 primers for the 18S rRNA subunit (4), and visualized on a 2% ethidium bromide agarose gel. An amplicon of fungal origin, approximately 550 bp and smaller than the approximately 700-bp plant ITS amplicon, was excised, purified, and then sequenced. This sequence was deposited in GenBank (Accession No. JF779687) and was 99% identical to two G. cichoracearum accessions (Nos. AB77627 and AB77625). Infected leaves were rubbed on leaves of four healthy plants and healthy leaves were rubbed onto other healthy leaves of two additional plants as controls in the greenhouse. Signs of powdery mildew developed on those plants inoculated with infected leaves after 7 to 10 days and the morphology of the fungus was identical to our previous description. To our knowledge, this is the first report of G. cichoracearum (E. cichoracearum) infecting Ruth's golden aster. We are not aware of the disease occurring in wild populations of the plant, but it does impact the production of micropropagated plants in the greenhouse. References: (1) D. A. Glawe et al. Online publication. doi:10.1094/PHP-2006-0405-01-BR. Plant Health Progress, 2006. (2) G. Newcombe and C. Nischwitz. Plant Dis. 88:312, 2004. (3) T. E. Seijo et al. Online publication. doi: 10.1094/PHP-2006-1214-01-BR. Plant Health Progress, 2006. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press Inc, New York, 1990.

scholarly journals First Report of Erysiphe cichoracearum Infecting Hedera canariensis var. azorica in Italy

Plant Disease ◽  
1999 ◽  
Vol 83 (2) ◽  
pp. 198-198
Author(s):  
C. Nali
Keyword(s):  
New York ◽  
Powdery Mildew ◽  
Citrullus Lanatus ◽  
Ornamental Plants ◽  
Morphological Characteristics ◽  
Hedera Helix ◽  
Cucumis Sativus L ◽  
First Report ◽  
Erysiphe Cichoracearum ◽  
English Ivy

A powdery mildew disease of variegated ivy (Hedera canariensis L. var. azorica) was observed on the Tyrrhenian coast in Tuscany (Italy) in spring 1998. Symptoms began as small, nearly circular reddish spots that later enlarged and coalesced. The hyaline mycelium produced abundant, ellipsoid conidia in long chains that ranged from 20 to 40 μm in length and from 12 to 25 μm in width. Cleistothecia were globose (100 to 120 μm diameter), dark brown (when mature) with a basal ring of mycelioid appendages, and contained several (up to 20) ovate asci, each generally containing two ascospores. Ascospores were hyaline, one-celled, ellipsoid (20 to 35 μm in length and 10 to 20 μm in width). The morphological characteristics of this fungus were those given for Erysiphe cichoracearum DC. Infection also was found on English ivy (Hedera helix L.). It is reported that this species is, occasionally, subject to powdery mildew caused by E. cichoracearum (1). Conidia from infected leaves were shaken onto leaves of melon (Cucumis melo L.), cucumber (Cucumis sativus L.), watermelon (Citrullus lanatus [Thunb.] Matsum. & Nakai), lettuce (Lactuca sativa L.), tomato (Lycopersicon esculentum Mill.), tobacco (Nicotiana tabacum L.) and variegated and English ivy. After 7 days, the disease was observed on cucumber, melon, watermelon, tobacco, and variegated ivy. Examination confirmed that test plants were infected with E. cichoracearum. This is the first report of E. cichoracearum on variegated ivy in Italy. Reference: (1) P. P. Pirone. 1970. Diseases and Pests of Ornamental Plants. The Ronald Press, New York.

First Report of Powdery Mildew of Coreopsis Species Caused by Golovinomyces cichoracearum in the Pacific Northwest

2006 ◽  
Vol 7 (1) ◽  
pp. 57
Author(s):  
Dean A. Glawe ◽  
Gary G. Grove ◽  
Mark Nelson
Keyword(s):  
Powdery Mildew ◽  
Pacific Northwest ◽  
Causal Agent ◽  
Diagnostic Features ◽  
First Report ◽  
The Pacific ◽  
Powdery Mildew Disease ◽  
Golovinomyces Cichoracearum

In 2005, the authors encountered a previously unreported powdery mildew disease of Coreopsis verticillata L. (whorled tickseed) ‘Zagreb’ and C. auriculata L. (lobed tickseed) ‘Nana’ in central Washington and determined the causal agent to be Golovinomyces cichoracearum (DC.) VP Gelyuta. This report documents the occurrence of G. cichoracearum on Coreopsis species in the Pacific Northwest, and describes diagnostic features of the disease and causal agent. Accepted for publication 2 March 2006. Published 5 April 2006.

scholarly journals First Report of Powdery Mildew Caused by Erysiphe diffusa, Oidium neolycopersici, and Podosphaera xanthii on Papaya in Taiwan

Plant Disease ◽  
2011 ◽  
Vol 95 (9) ◽  
pp. 1188-1188 ◽  
Author(s):  
J.-G. Tsay ◽  
R.-S. Chen ◽  
H.-L. Wang ◽  
W.-L. Wang ◽  
B.-C. Weng
Keyword(s):  
Powdery Mildew ◽  
Morphological Characteristics ◽  
Its Region ◽  
Podosphaera Xanthii ◽  
Oidium Neolycopersici ◽  
First Report ◽  
Plastic Bags ◽  
The World ◽  
Golovinomyces Cichoracearum ◽  
Powdery Mildew Fungi

Powdery mildew can be found in most papaya (Carica papaya L.) fields during the winter and spring seasons in Taiwan. It usually causes severe yellowing of the leaf lamina and petiole and serious defoliation. Three types of powdery mildew fungi were isolated from papaya leaves in Chiayi City (23.28°N, 120.28°E) at the beginning of 2008. Conidia of the first one were single, globose, hyaline, and 24 to 36 × 14 to 18 μm (average 30.2 × 15.6 μm) without fibrosin bodies and with straight or occasionally flexuous conidiophores at the base. The second one had short pseudo-chains of two to four conidia which were ellipsoidal to ovoid, hyaline, and 24 to 40 × 12 to 16 μm (average 29.7 × 13.4 μm) without fibrosin bodies. The third type had chains of ellipsoidal conidia that were hyaline, 24 to 28 × 12 to 16 μm (average 26.3 × 14.4 μm) and contained fibrosin bodies. To confirm the identity of the three fungi, the internal transcribed spacer (ITS) region of rDNA was amplified using the primer pairs G1 (5′-TCC GTA GGT GAA CCT GCG GAA GGA T-3′)/Ed2 (5′-CGC GTA GAG CCC ACG TCG GA-3′), G1 (5′-TCC GTA GGT GAA CCT GCG GAA GGA T-3′)/On2 (5′-TGT GAT CCA TGT GAC TGG AA-3′), and S1 (5′-GGA TCA TTA CTG AGC GCG AGG CCC CG-3′)/S2 (5′-CGC CGC CCT GGC GCG AGA TAC A-3′). The alignment of obtained sequences (GenBank Accession Nos. GU358452, 507 bp; GU358451, 580 bp; and GU358450, 455 bp) showed a sequence identity of 100, 99, and 99% with the ITS sequences of Erysiphe diffusa, Oidium neolycopersici, and Podosphaera xanthii (GenBank Accession Nos. FJ378880, EU909694, and GQ927254), respectively. On the basis of morphological characteristics and ITS sequence similarities, these fungi were identified as E. diffusa (Cooke & Peck) U. Braun & S. Takam., O. neolycopersici L. Kiss, and P. xanthii (Castagne) U. Braun & S. Takam., respectively (1,3). Single colonies on papaya leaves infected with powdery mildew were identified in the laboratory and maintained on papaya leaves as inoculum. Pathogenicity was confirmed through inoculations by gently pressing a single colony of each fungus onto leaves of healthy papaya seedlings (cv. Horng-Fe). Five seedlings were inoculated for each fungus and then covered with plastic bags for 2 days. Five noninoculated seedlings served as control. After inoculation, treated plants were maintained separately from the control in different rooms of a greenhouse at 25°C under natural daylight conditions. Seven days after inoculation, typical symptoms of powdery mildew were observed on inoculated plants, but not on noninoculated plants. The same species from diseased lesions following artificial inoculation with each fungus were identified with light microscopy. Papaya was previously described as a host to O. caricae Noack in many tropical and subtropical areas of the world including Taiwan (2). However E. cruciferarum, Golovinomyces cichoracearum, Oidiopsis sicula, O. caricae, O. caricae-papayae, O. caricicola, O. indicum, O. papayae, Ovulariopsis papayae, P. caricae-papayae, P. macularis, P. xanthii, and Streptopodium caricae were reported to infect papaya (4). To our knowledge, this is the first report of papaya powdery mildew caused by E. diffusa and O. neolycopersici in the world and the first report of the three fungi found on papaya in Taiwan. References: (1) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000. (2) H. S. Chien and H. L. Wang. J. Agric. Res. China 33:320, 1984. (3) L. Kiss et al. Mycol. Res. 105:684, 2001. (4) J. R. Liberato et al. Mycol. Res. 108:1185, 2004.

scholarly journals First report of Golovinomyces cichoracearum associated with powdery mildew on Helianthus tuberosus in Korea

2012 ◽  
Vol 7 (1) ◽  
pp. 35-37 ◽  
Author(s):  
Sung-Eun Cho ◽  
Mi-Jeong Park ◽  
Ji-Hyun Park ◽  
Kyung-Sook Han ◽  
Hyeon-Dong Shin
Keyword(s):  
Powdery Mildew ◽  
Helianthus Tuberosus ◽  
First Report ◽  
Golovinomyces Cichoracearum

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 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 First Report of Powdery Mildew Caused by Golovinomyces biocellatus on Peppermint in California

Plant Disease ◽  
2010 ◽  
Vol 94 (2) ◽  
pp. 276-276 ◽  
Author(s):  
D. B. Marcum ◽  
K. Perez ◽  
R. M. Davis
Keyword(s):  
Powdery Mildew ◽  
Fungal Growth ◽  
Universal Primers ◽  
Mentha Piperita ◽  
Exact Match ◽  
First Report ◽  
Plastic Bag ◽  
The One ◽  
Shasta County ◽  
Disease Free

In August of 2009, powdery mildew was observed on peppermint (Mentha piperita L.) in several commercial fields in the Fall River Valley of eastern Shasta County, California. Plant growth was apparently reduced by the disease, but its impact on yield was unknown. White fungal growth was restricted to the adaxial surfaces, where colonies were thin and effused. Heavily infected leaves developed a reddish tint as growth prematurely ceased. Doliform conidia ([26.6-] 29.2 [-31.7] × [13.2-] 15.6 [-16.8] μm) were produced in chains of approximately six conidia. Foot cells were cylindrical ([41.3-] 55.2 [-75.0] × [11.2-] 12.0 [-12.8] μm). Immature chasmothecia were yellowish brown and approximately 100.0 μm in diameter with flexuous, mycelium-like appendages up to 200 μm long. All these features were consistent with those of Golovinomyces biocellatus. Asci were not observed. To confirm the identity of the fungus, nuclear rDNA internal transcribed spacer (ITS) regions were amplified by PCR with universal primers ITS4 and ITS5. The sequence (537 bp) was an exact match for several submissions of G. biocellatus in GenBank (e.g., Accession No. EU035602, a sequence of the fungus from mint in Australia [1]). Pathogenicity was confirmed by brushing spores from naturally infected leaves onto three rooted cuttings of M. piperita ‘Black Mitchum’. After the plants were covered with a plastic bag for 36 h to maintain high humidity, they were kept on a greenhouse bench at 23 to 28°C. Three noninoculated plants, which served as controls, were placed in another greenhouse in similar conditions. The experiment was repeated once. All inoculated plants developed signs of powdery mildew within 7 days of inoculation whereas noninoculated plants remained disease free. The fungus on inoculated leaves was morphologically indistinguishable from the one used to inoculate the plants. To our knowledge, this is the first report of G. biocellatus on peppermint in California. References: (1) J. R. Liberato and J. H. Cunnington. Australas, Plant Dis. Notes 2:38, 2007.

scholarly journals First Report of Powdery Mildew (Oidium sp.) on Pincushion Flower (Scabiosa columbaria) in New York

Plant Disease ◽  
2009 ◽  
Vol 93 (3) ◽  
pp. 316-316 ◽  
Author(s):  
T. Jankovics ◽  
L. Kiss ◽  
R. E. Niks ◽  
M. L. Daughtrey
Keyword(s):  
New York ◽  
Powdery Mildew ◽  
The Netherlands ◽  
Morphological Characteristics ◽  
The United States ◽  
Its Sequences ◽  
Herbarium Specimens ◽  
Chelidonium Majus ◽  
Oidium Neolycopersici ◽  
First Report

Scabiosa columbaria (Dipsacaceae) is a popular perennial ornamental in the United States. It is native to Europe and was introduced to North America by nursery trade only recently. In the spring of 2006, symptoms of powdery mildew infection were observed on overwintered plants of S. columbaria cv. Butterfly Blue in a nursery in Cutchogue, NY. White powdery mildew mycelia with abundant sporulation were observed on upper and lower leaf surfaces. The portions of leaves with powdery mildew colonies often showed purplish discoloration. Conidia were cylindric to doliiform, measured 20 to 33 × 10 to 15 μm, and were produced singly on 60 to 130 μm long conidiophores consisting of a foot-cell measuring 20 to 50 × 6 to 10 μm, followed by one to three, 12 to 40 μm long cells. Hyphal appressoria were lobed or multilobed. The teleomorph stage was not found. On the basis of these characteristics, the pathogen was identified as an Oidium sp. belonging to the subgenus Pseudoidium. Recently, an anamorphic powdery mildew fungus with similar morphological characteristics, identified as Erysiphe knautiae, was reported on S. columbaria cv. Butterfly Blue in Washington (2). E. knautiae is a common powdery mildew species of dipsacaceous plants such as Scabiosa spp. and Knautia spp. in Europe and Asia (1). To determine whether the fungus reported here was E. knautiae, DNA was extracted from its mycelium, and the internal transcribed spacer (ITS) region of the ribosomal DNA was amplified and sequenced as described earlier (4). No ITS sequences are available in public DNA databases for E. knautiae, thus, we determined this sequence in a specimen of E. knautiae collected from Knautia arvensis in The Netherlands. Herbarium specimens of the Oidium sp. infecting S. columbaria in New York and E. knautiae from the Netherlands were deposited at the U.S. National Fungus Collections under accession numbers BPI 878259 and BPI 878258, respectively. The ITS sequence from Oidium sp. infecting S. columbaria in New York (GenBank Accession No. EU377474) differed in two nucleotides from that of E. knautiae infecting K. arvensis in the Netherlands (GenBank Accession No. EU377475). These two ITS sequences were also more than 99% similar to those of some newly emerged anamorphic powdery mildew fungi: Oidium neolycopersici and other Oidium spp. infecting Chelidonium majus, Passiflora caerulea, and some crassulaceous plants (3,4). Thus, it is unclear whether the fungus reported here was E. knautiae known from Eurasia or an Oidium sp. that has acquired pathogenicity to S. columbaria. To our knowledge, this is the first report of powdery mildew on S. columbaria in New York. References: (1) U. Braun. Beih. Nova Hedwigia 89:1, 1987. (2) D. A. Glawe and G. G. Grove. Online publication. doi:10.1094/PHP-2005-1024-01-BR. Plant Health Progress, 2005. (3) B. Henricot. Plant Pathol. 57:779, 2008. (4) T. Jankovics et al. Phytopathology 98:529, 2008.

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