First Report of Podosphaera fusca Causing Powdery Mildew of Cosmos caudatus in Malaysia

Cosmos caudatus Kunth. (Asteraceae), commonly known as ulam raja, is widely grown as an herbal aromatic shrub. In Malaysia, its young leaves are popularly eaten raw as salad with other greens and have been reported to possess extremely high antioxidant properties, which may be partly responsible for some of its believed medicinal functions. In early 2010, a suspected powdery mildew was observed on ulam raja plants at the Agricultural Park of Universiti Putra Malaysia. Initially, individual, white, superficial colonies were small and almost circular. Later, they enlarged and coalesced to cover the whole abaxial leaf surface. With development of the disease, all green parts (leaves, stems, and petioles) became covered with a continuous mat of mildew, giving a dusty appearance. Newly emerged leaves rapidly became infected. Diseased leaves ultimately senesced and dried up, making them aesthetically unattractive and unmarketable. The pathogen produced conidia in short chains (four to six conidia) on erect conidiophores. Conidiophores were unbranched, cylindrical, 125 to 240 μm long, with a slightly swollen foot cell. Individual conidia were hyaline, ellipsoid, and 25 to 30 (27.5) × 15 to 20 (17.5) μm with fibrosin inclusions. Morphological descriptions were consistent with those described for Sphaerotheca fuliginea or S. fusca, which has lately been reclassified as Podosphaera fusca (1). From extracted genomic DNA of P. fusca UPM UR1, the internal transcribed spacer (ITS) region was amplified with ITS1 (5′-TCCGTAGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′). A BLAST search of GenBank with an ITS rDNA sequence of this fungus (GenBank Accession No. HQ589357) showed a maximum identity of 98% to the sequences of two P. fusca isolates (GenBank Accession Nos. AB525915.1 and AB525914.1). To satisfy Koch's postulates, the pathogenicity of fungal strain UPM UR1 was verified on 4-week-old plants. Inoculation was carried out by gently rubbing infected leaves onto healthy plants of C. caudatus. Ten pots of inoculated plants were kept under a plastic humid chamber and 10 pots of noninoculated plants, placed under another chamber, served as controls. After 48 h, the plants were then placed under natural conditions (25 to 28°C). Powdery mildew symptoms, similar to those on diseased field plants, appeared after 7 days on all inoculated plants. The white, superficial colonies enlarged and merged to cover large areas within 2 weeks. The infected leaf tissues became necrotic 6 to 8 days after the appearance of the first symptoms. Sporulation of P. fusca was observed on all infected leaves and stems. No symptoms were seen on the control plants. To our knowledge, this is the first report of P. fusca causing powdery mildew on C. caudatus in Malaysia. This pathogen has also been reported previously to be economically important on a number of other hosts. With ulam raja plants, more attention should be given to prevention and control measures to help manage this disease. Reference: (1) U. Braun and S. Takamatsu. Schlechtendalia 4:1, 2000.

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

Plant Disease ◽

10.1094/pdis-10-12-0982-pdn ◽

2013 ◽

Vol 97 (6) ◽

pp. 843-843 ◽

Cited By ~ 2

Author(s):

Y. J. La ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

North America ◽

Powdery Mildew ◽

Its Region ◽

The United States ◽

Control Measures ◽

Base Substitution ◽

Width Ratio ◽

First Report ◽

Platanus Occidentalis ◽

Young Leaves

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

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First Report of Powdery Mildew Caused by Golovinomyces ambrosiae on Verbena bonariensis in Korea

Plant Disease ◽

10.1094/pdis-02-21-0349-pdn ◽

2021 ◽

Author(s):

In-Young Choi ◽

Ho-Jong Ju ◽

Kui-Jae Lee ◽

Hyeon-Dong Shin

Keyword(s):

Powdery Mildew ◽

Large Subunit ◽

Morphological Characteristics ◽

Morphological Characterization ◽

Control Measures ◽

Width Ratio ◽

Infected Leaf ◽

Voucher Specimen ◽

First Report ◽

Pcr Products

Verbena bonariensis L., named as purple-top vervain or Argentinian vervain, is native to tropical South America. It is cultivated worldwide as an ornamental plant. During summer and autumn of 2020, over 50% of the leaves of V. bonariensis were found infected with powdery mildew in a flower garden in Seoul (37°35'19"N 127°01'07"E), Korea. White, superficial mycelia developed initially on the leaves and subsequently covered surfaces of leaves and stems, are resulting in leaf discoloration, early defoliation, and shoots distortion. Heavily infected plants lost ornamental value. A representative voucher specimen was deposited in the Korea University herbarium (KUS-F32168). Morphological characterization and measurements of conidiophores and conidia were carried out using fresh samples. Microscopic observation showed that aAppressoria on the superficial hypha were nipple-shaped, but rarely found or nearly absent. Conidiophores (n = 30) were cylindrical, 110 to 220 × 10 to 12 µm, and produced 2 to 5 immature conidia in chains with a sinuate outline, followed by 2 to 3 short cells. Foot-cells of conidiophores were straight, cylindrical, and 46 to 90 μm long. Conidia (n = 30) were hyaline, ellipsoid to doliiform, 28 to 40 × 18 to 24 μm with a length/width ratio of 1.3 to 2.0, and contained small be like oil-like drops, but without distinct fibrosin bodies. Primary conidia were apically rounded and sub-truncate at the base. Germ tubes were produced at perihilar position of the conidia. Chasmothecia were not observed. These morphological characteristics were typical of the conidial stage of the genus Golovinomyces (Braun and Cook 2012, Qiu et al. 2020). To identify the fungus, rDNA was extracted from the voucher sample. PCR products were amplified 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). The resulting sequences were registered to GenBank (MW599742 for ITS, and MW599743 for LSU). Using Blast’n search of GenBank, sequences showed 100% identity for ITS and LSU with G. ambrosiae (MT355557, KX987303, MH078047 for ITS, and AB769427, AB769426 for LSU), respectively. Thus, based on morphology and molecular analysis, the isolate on V. bonariensis in Korea was identified as G. ambrosiae (Schwein.) U. Braun & R.T.A. Cook. Pathogenicity tests were carried out by touching an infected leaf onto healthy leaves of disease-free pot-grown plants using a replication of five plants, with five non-inoculated plants used as controls. After 7 days, typical powdery mildew colonies started to appear on the inoculated leaves. The fungus on inoculated leaves was morphologically identical to that originally observed in the field. All non-inoculated control leaves remained symptomless. On different global Verbena species, tThere have been many reports of Golovinomyces powdery mildews including G. cichoracearum s.lat., G. longipes, G. monardae, G. orontii s.lat., and G. verbenae (Farr and Rossman 2021). In China, G. verbenae was recorded on V.erbena phlogiflora (Liu et al. 2006). Golovinomyces powdery mildew has not been reported on Verbena spp. in Korea. Powdery mildew has been reported on V. bonariensis in California, but identity of the causal agent had not been reported. To our knowledge, this is the first report on the identity of the powdery mildew caused by G. ambrosiae on V. bonariensis in Korea. Since heavily infected plants lost ornamental value, appropriate control measures should be developed.

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First Report of Podosphaera xanthii Causing Powdery Mildew on Mungbean (Vigna radiata) in Taiwan

Plant Disease ◽

10.1094/pdis-09-20-2092-pdn ◽

2021 ◽

Author(s):

Zong-ming Sheu ◽

Ming-hsueh Chiu ◽

Lawrence Kenyon

Keyword(s):

Powdery Mildew ◽

Vigna Radiata ◽

Morphological Characteristics ◽

Resistance Breeding ◽

Its Region ◽

Infected Leaf ◽

Pathogenicity Test ◽

Causal Organism ◽

First Report ◽

Powdery Mildew Pathogen

Mungbean (Vigna radiata L.) is routinely grown in the experimental fields at the headquarters of the World Vegetable Center (23°6'30.88"N, 120°17'51.31"E) for breeding, research and germplasm multiplication. In a spring 2016 mungbean trial, about 50% of the plants were affected with powdery mildew. The white, powdery-like patches first appeared on the upper leaf surfaces, and soon developed to grey patches on both sides of the leaves. Purple to brown discoloration appeared on the underside of the infected leaf. Microscopy examination revealed that the causal organism was not Erysiphe polygoni, which had previously been documented as the powdery mildew pathogen on mungbean in Taiwan (Hartman et al. 1993). The fungus produced typical structures of the powdery mildew Euoidium, anamorph of the genus Podosphaera. The mycelium consisted of septate, flexuous hyphae with indistinct appressoria. The erect conidiophores arising from superficial hyphae varied from straight or slightly curved to curled. Three to ten conidia were borne in long chains with crenate edges. Foot-cells were straight, cylindrical and measured 30 to 52 µm long. Conidia were hyaline, ellipsoid-ovoid to barrel-shaped, with fibrosin bodies, and measured 27 to 33 (mean = 30.4) × 15 to 20 (mean = 16.6) µm. Germ tubes were clavate and occasionally forked, and were produced from the lateral sites of the conidia. No chasmothecia were found in the samples. The morphological characteristics were consistent with P. xanthii (Castagne) U. Braun & Shishkoff (Braun & Cook 2012). To confirm the identity, the internal transcribed spacer (ITS) region of rDNA and partialβ-tubulin gene (TUB2) for the isolate MG3 were amplified with the primers ITS4/ITS5 (White et al. 1990) and BtuF5/BtuR7a (Ellingham et al. 2019), respectively. BLASTn analysis revealed the ITS sequence (MN833717) was 100% identical to many records of P. xanthii whereas the TUB2 sequence (MW363957) was 100% identical to a record of P. fusca (syn. P. xanthii; KC333362) in NCBI GenBank. A pathogenicity test was conducted by dusting conidia from an infected leaf onto six healthy four-week-old mungbean plants (cv ‘Tainan No. 3’). Another three plants were not inoculated and were used as control. All the plants were maintained in a greenhouse at 25 to 28°C. All inoculated plants developed powdery mildew symptoms after 10 days, whereas the control plants remained symptomless. To our knowledge, this is the first report of P. xanthii causing disease on mungbean in Taiwan. P. xanthii also has been reported on mungbean in Thailand (Meeboon et al. 2016), while other records referring to E. polygoni infecting Vigna spp. are from Brazil and Fiji (Farr & Rossman 2020). Although both P. xanthii and E. polygoni have now been reported as causing powdery mildew on mungbean in Taiwan, which species predominates or is more important remains unclear. A comprehensive survey with accurate species identification is required to develop effective management of the disease, particularly for resistance breeding.

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First Report of Powdery Mildew of Platanus × acerifolia and P. occidentalis Caused by Erysiphe platani in Greece

Plant Disease ◽

10.1094/pdis-07-14-0713-pdn ◽

2015 ◽

Vol 99 (2) ◽

pp. 286-286 ◽

Cited By ~ 3

Author(s):

E. K. Ligoxigakis ◽

E. A. Markakis ◽

I. A. Papaioannou ◽

M. A. Typas

Keyword(s):

Powdery Mildew ◽

Infected Plant ◽

Control Measures ◽

Universal Primers ◽

Morphological Description ◽

Its2 Region ◽

Conidial Suspension ◽

Platanus Acerifolia ◽

First Report ◽

Young Leaves

London planetrees (Platanus × acerifolia, syn. P. × hispanica), American sycamores (P. occidentalis), and oriental planes (P. orientalis) are widely planted as urban shade trees throughout Greece and many other countries. In June 2012, typical symptoms of a powdery mildew were detected on all sycamores (10 trees) along a central avenue of Heraklion (Crete, Greece), with the disease affecting approximately 80% of the leaves of all infected trees. In August 2013, similar symptoms were observed on 20% of the leaves of all three London planes in a small grove in the Vrysses area of Lasithi (Crete, Greece). In both cases, the disease was severe, with white superficial colonies developing amphigenously on leaves, twigs, floral peduncles, inflorescences, and fruits. The colonies were initially distinct and circular but gradually enlarged and often coalesced to cover the entire leaf blade. Young leaves appeared curled and chlorotic, occasionally leading to defoliation. For the morphological description of the pathogen, samples from seven infected P. occidentalis and three P. × acerifolia trees were microscopically characterized. In all samples, the pathogen's mycelium was branched, septate, and hyaline, with lobed appressoria; conidiophores were erect, cylindrical, unbranched, and consisted of three to four (to five) cells; and conidia were single or in short chains (two to four), ellipsoid or doliiform, with a truncated base and rounded apex. Their dimensions were 24.3 to 48.6 × 15.8 to 27.9 μm (averaging 39.2 × 21.2 μm; n = 100), and their surfaces appeared reticulate. The teleomorph was never observed. Total fungal DNA was extracted from conidia harvested from affected leaves of one infected plant of each of P. occidentalis and P. × acerifolia planes, and the ITS1-5.8S-ITS2 region was PCR-amplified with universal primers 18S-ITS1 and 28S-ITS2 (2) and sequenced (GenBank Accession Nos. KM068123 and KM068124, respectively). A BLASTn search of GenBank revealed 100% identity of both samples to Erysiphe platani strains described on P. orientalis in Greece (JQ365943) and P. occidentalis in Brazil (KF499270). Based on the morphological and molecular analyses, the pathogen was identified as E. platani (Howe) U. Braun & S. Takam. (formerly known as Microsphaera platani Howe) (1). To prove pathogenicity and fulfill Koch's postulates, 10 1-year-old seedlings of each of P. occidentalis and P. × acerifolia hosts were artificially inoculated with conidia obtained from naturally infected plants of the corresponding species, with two methods: (i) five plants of each host were dusted with conidia from diseased leaves, and (ii) the remaining five seedlings of each plane were sprayed with a conidial suspension of the fungus (107 conidia ml−1), while five additional control plants of each species were treated only with sterile distilled water. All plants were maintained in the greenhouse at 25 ± 3°C, with 90% humidity. Powdery mildew symptoms, which appeared 9 and 15 days after inoculation on all dusted and sprayed plants, respectively, were similar to those observed on naturally infected trees, whereas no symptoms were observed on control plants. Although E. platani is known to infect plane species in several parts of the world (1), including oriental planes (P. orientalis and P. orientalis var. cretica) in Greece (3), this is the first report of E. platani causing disease of P. occidentalis and P. × acerifolia in Greece, underlining the need for appropriate control measures to prevent significant losses to the local ornamental industry. 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) I. A. Papaioannou et al. Eur. J. Plant Pathol. 136:577, 2013. (3) D. J. Vakalounakis and E. Klironomou. EPPO Bull. 25:463, 1995.

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First Report of Powdery Mildew Caused by Podosphaera xanthii on Hibiscus mutabilis in Korea

Plant Disease ◽

10.1094/pdis-01-13-0065-pdn ◽

2013 ◽

Vol 97 (8) ◽

pp. 1118-1118

Author(s):

S. E. Cho ◽

J. H. Park ◽

S. K. Lee ◽

C. H. Shin ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Natural Habitat ◽

Morphological Characteristics ◽

Its Region ◽

Width Ratio ◽

Korean Isolate ◽

First Report ◽

Public Garden ◽

Young Leaves ◽

Length Width

Hibiscus mutabilis L., known as cotton rose, is a deciduous shrub native to China. Horticultural varieties of the species are widely planted throughout the world (4). In September 2012, typical powdery mildew symptoms on the cotton rose were observed in a public garden of Jeju City, Korea. Powdery mildew colonies were circular to irregular white patches on both sides of the leaves and also on young stems and sepals. As the disease progressed, white mycelial growth covered the entire shoot portion, causing leaf distortion. In the middle of November, numerous chasmothecia were formed on the lesions. Voucher specimens (n = 4) were deposited in the Korea University Herbarium (KUS). Hyphal appressoria were only swollen part of hyphae or occasionally nipple-shaped. Conidiophores were 140 to 275 × 10 to 11.5 μm and produced 2 to 8 immature conidia in chains with a crenate outline. Foot-cells of conidiophores were straight, 30 to 65 μm long, and cylindric. Conidia were hyaline, ellipsoid-ovoid, and measured 27 to 42 × 17.5 to 21 μm with a length/width ratio of 1.5 to 2.4, and had distinct fibrosin bodies. Chasmothecia were amphigenous, cauligenous, 85 to 110 μm in diameter, and contained one ascus each. Peridium cells of chasmothecia were irregularly polygonal, large, and 15 to 38 μm wide. Appendages were mycelioid, 1- to 6-septate, brown at the base, and becoming paler. Asci were sessile, oval to broadly fusiform, with terminal oculus of 15 to 20 μm wide. Ascospores numbered eight per ascus were ellipsoidal, 19 to 25 × 14 to 16 μm. The morphological characteristics were consistent with previous records of P. xanthii (Castagne) U. Braun & Shishkoff (1). To confirm the identification, the complete internal transcribed spacer (ITS) region of rDNA from isolate KUS-F27134 was amplified with the primers ITS5 and P3 and sequenced (3). The resulting sequence of 477 bp was deposited in GenBank (Accession No. KC460208). The Korean isolate showed >99% similarity with dozens of sequences of P. xanthii ex cucurbitaceous hosts (e.g., JQ912061, JQ409565, HM070403, etc.) as well as Podosphaera sp. ex H. mutabilis from Japan (AB040308). Pathogenicity was confirmed through inoculation tests by gently pressing diseased leaves onto young leaves of three asymptomatic, potted 2-year-old seedlings. Three non-inoculated seedlings were used as controls. Plants were maintained in a greenhouse at 24 to 30°C. Inoculated leaves developed symptoms after 7 days, whereas the control plants remained symptomless. The fungus present on the inoculated leaves was morphologically identical to that observed on the original diseased leaves, fulfilling Koch's postulates. Powdery mildew infections of H. mutabilis associated with P. xanthii (including P. fuliginea in broad sense) have been known in China, Japan, and Taiwan (1,2). To our knowledge, this is the first report of powdery mildew caused by P. xanthii on H. mutabilis in Korea. Since Jeju, the southmost island of Korea, is the only habitat of cotton rose in Korea and is the northmost natural habitat in Asia, powdery mildew is a new threat to the health of wild populations of cotton rose. References: (1) U. Braun and R. T. A. Cook. Taxonomic Manual of the Erysiphales (Powdery Mildews), CBS Biodiversity Series No.11. CBS, Utrecht, 2012. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication, ARS, USDA, retrieved January 18, 2013. (3) S. Takamatsu et al. Mycol. Res. 113:117, 2009. (4) D. A. Wise. J. Hered. 64:285, 1973.

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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 pulchra on Cornus florida in Italy

Plant Disease ◽

10.1094/pdis-93-3-0320c ◽

2009 ◽

Vol 93 (3) ◽

pp. 320-320 ◽

Cited By ~ 2

Author(s):

A. Garibaldi ◽

D. Bertetti ◽

M. L. Gullino

Keyword(s):

Powdery Mildew ◽

Its Region ◽

The United States ◽

Deciduous Tree ◽

Herbarium Specimens ◽

Pathogenicity Test ◽

Cornus Florida ◽

First Report ◽

Flowering Dogwood ◽

Young Leaves

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

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First report of Podosphaera fusca causing powdery mildew on asparagus bean in Taiwan

Journal of Plant Pathology ◽

10.1007/s42161-021-00862-w ◽

2021 ◽

Author(s):

Yi-Ting Xiao ◽

Chao-Jen Wang ◽

Tung-Chin Huang ◽

Yuan-Min Shen

Keyword(s):

Powdery Mildew ◽

First Report ◽

Asparagus Bean ◽

Podosphaera Fusca

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First Report of Leaf Blight and Stem Canker of Pachysandra terminalis Caused by Pseudonectria pachysandricola in Korea

Plant Disease ◽

10.1094/pdis-09-11-0813 ◽

2012 ◽

Vol 96 (2) ◽

pp. 287-287

Author(s):

K. S. Han ◽

J. H. Park ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

United States ◽

Its Region ◽

Stem Canker ◽

The United States ◽

Culture Collection ◽

Leaf Blight ◽

First Report ◽

Cornell University ◽

Plastic Bags ◽

Young Leaves

Pachysandra terminalis Siebold & Zucc., known as Japanese pachysandra, is a creeping evergreen perennial belonging to the family Buxaceae. In April 2011, hundreds of plants showing symptoms of leaf blight and stem canker with nearly 100% incidence were found in a private garden in Suwon, Korea. Plants with the same symptoms were found in Seoul in May and Hongcheon in August. Affected leaves contained tan-to-yellow brown blotches. Stem and stolon cankers first appeared as water soaked and developed into necrotic lesions. Sporodochia were solitary, erumpent, circular, 50 to 150 μm in diameter, salmon-colored, pink-orange when wet, and with or without setae. Setae were hyaline, acicular, 60 to 100 μm long, and had a base that was 4 to 6 μm wide. Conidiophores were in a dense fascicle, not branched, hyaline, aseptate or uniseptate, and 8 to 20 × 2 to 3.5 μm. Conidia were long, ellipsoid to cylindric, fusiform, rounded at the apex, subtruncate at the base, straight to slightly bent, guttulate, hyaline, aseptate, 11 to 26 × 2.5 to 4.0 μm. A single-conidial isolate formed cream-colored colonies that turned into salmon-colored colonies on potato dextrose agar (PDA). Morphological and cultural characteristics of the fungus were consistent with previous reports of Pseudonectria pachysandricola B.O. Dodge (1,3,4). Voucher specimens were housed at Korea University (KUS). Two isolates, KACC46110 (ex KUS-F25663) and KACC46111 (ex KUS-F25683), were accessioned in the Korean Agricultural Culture Collection. Fungal DNA was extracted with DNeasy Plant Mini DNA Extraction Kits (Qiagen Inc., Valencia, CA). The complete internal transcribed spacer (ITS) region of rDNA was amplified with the primers ITS1/ITS4 and sequenced using ABI Prism 337 automatic DNA sequencer (Applied Biosystems, Foster, CA). The resulting sequence of 487 bp was deposited in GenBank (Accession No. JN797821). This showed 100% similarity with a sequence of P. pachysandricola from the United States (HQ897807). Isolate KACC46110 was used in pathogenicity tests. Inoculum was prepared by harvesting conidia from 2-week-old cultures on PDA. Ten young leaves wounded with needles were sprayed with conidial suspensions (~1 × 106 conidia/ml). Ten young leaves that served as the control were treated with sterile distilled water. Plants were covered with plastic bags to maintain a relative humidity of 100% at 25 ± 2°C for 24 h. Typical symptoms of brown spots appeared on the inoculated leaves 4 days after inoculation and were identical to the ones observed in the field. P. pachysandricola was reisolated from 10 symptomatic leaf tissues, confirming Koch's postulates. No symptoms were observed on control plants. Previously, the disease was reported in the United States, Britain, Japan, and the Czech Republic (2,3), but not in Korea. To our knowledge, this is the first report of P. pachysandricola on Pachysandra terminalis in Korea. Since this plant is popular and widely planted in Korea, this disease could cause significant damage to nurseries and the landscape. References: (1) B. O. Dodge. Mycologia 36:532, 1944. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , September 24, 2011. (3) I. Safrankova. Plant Prot. Sci. 43:10, 2007. (4) W. A. Sinclair and H. H. Lyon. Disease of Trees and Shrubs. 2nd ed. Cornell University Press, Ithaca, NY, 2005.

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First Report of Powdery Mildew Caused by Golovinomyces biocellatus on Agastache rugosa in Korea

Plant Disease ◽

10.1094/pdis-03-14-0298-pdn ◽

2014 ◽

Vol 98 (9) ◽

pp. 1278-1278 ◽

Cited By ~ 1

Author(s):

S. E. Cho ◽

J. H. Park ◽

S. H. Hong ◽

I. Y. Choi ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Severe Disease ◽

Morphological Characteristics ◽

Control Measures ◽

Control Treatment ◽

Width Ratio ◽

Korean Isolate ◽

Pathogenicity Test ◽

Agastache Rugosa ◽

First Report

Agastache rugosa (Fisch. & C.A. Mey.) Kuntze, known as Korean mint, is an aromatic plant in the Lamiaceae. It is widely distributed in East Asian countries and is used as a Chinese traditional medicine. In Korea, fresh leaves are commonly added to fish soups and stews (3). In November 2008, several dozen Korean mints plants growing outdoors in Gimhae City, Korea, were found to be severely infected with a powdery mildew. The same symptoms had been observed in Korean mint plots in Busan and Miryang cities from 2008 to 2013. Symptoms first appeared as thin white colonies, which subsequently developed into abundant hyphal growth on stems and both sides of the leaves. Severe disease pressure caused withering and senescence of the leaves. Voucher specimens (n = 5) were deposited in the Korea University Herbarium (KUS). Appressoria on the mycelium were nipple-shaped or nearly absent. Conidiophores were 105 to 188 × 10 to 13 μm and produced 2 to 4 immature conidia in chains with a sinuate outline, followed by 2 to 3 cells. Foot-cells of the conidiophores were straight, cylindrical, slightly constricted at the base, and 37 to 58 μm long. Conidia were hyaline, ellipsoid to barrel-shaped, measured 25 to 40 × 15 to 23 μm (length/width ratio = 1.4 to 2.1), lacked distinct fibrosin bodies, and showed reticulate wrinkling of the outer walls. Primary conidia were obconically rounded at the apex and subtruncate at the base. Germ tubes were produced at the perihilar position of conidia. No chasmothecia were observed. The structures described above were typical of the Oidium subgenus Reticuloidium anamorph of the genus Golovinomyces. The measurements and morphological characteristics were compatible with those of G. biocellatus (Ehrenb.) V.P. Heluta (1). To confirm the identification, molecular analysis of the sequence of the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) of isolate KUS-F27200 was conducted. The complete ITS rDNA sequence was amplified using primers ITS5 and P3 (4). The resulting 514-bp sequence was deposited in GenBank (Accession No. KJ585415). A GenBank BLAST search of the Korean isolate sequence showed >99% similarity with the ITS sequence of many G. biocellatus isolates on plants in the Lamiaceae (e.g., Accession Nos. AB307669, AB769437, and JQ340358). Pathogenicity was confirmed by gently pressing diseased leaf onto leaves of five healthy, potted Korean mint plants. Five non-inoculated plants served as a control treatment. Inoculated plants developed symptoms after 7 days, whereas the control plants remained symptomless. The fungus present on inoculated plants was identical morphologically to that observed on the original diseased plants. The pathogenicity test was repeated with identical results. A powdery mildew on A. rugosa caused by G. biocellatus was reported from Romania (2). To our knowledge, this is the first report of powdery mildew caused by G. biocellatus on A. rugosa in Korea. The plant is mostly grown using organic farming methods with limited chemical control options. Therefore, alternative control measures should be considered. References: (1) U. Braun and R. T. A. Cook. Taxonomic Manual of the Erysiphales (Powdery Mildews), CBS Biodiversity Series No. 11. CBS, Utrecht, 2012. (2) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., online publication, USDA ARS, retrieved 17 February 2014. (3) T. H. Kim et al. J. Sci. Food Agric. 81:569, 2001. (4) S. Takamatsu et al. Mycol. Res. 113:117, 2009.

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