First Record of Erysiphe cf. elevata on Cerbera manghas (Apocynaceae) in China

Cerbera manghas L. (sea mango) is an evergreen shrub or small flowering tree up to12 m tall. It naturally occupies coastal habitats and is distributed from Seychelles in the Indian Ocean eastward to French Polynesia. In China, it is a popular ornamental urban species growing in roadside green belts, public parks, and residential areas in various coastal cities. In March 2019, powdery mildew symptoms were observed on six trees of C. manghas growing in a residential area near Minjiang University campus, in Minhou district of Fuzhou city. Approximately 60 % of leaves per plant were infected. Initial symptoms appeared as small circular to irregular white patches of superficial mycelia, conidiophores and conidia covered on both surfaces of leaves, which later coalesced and formed dense covered, resulting in discoloration and defoliation. Hyphae were septate, hyaline, smooth with simple to multilobed lobed appressoria formed singly or opposite pairs and 5 to 8 µm diam. Conidiophores were erect and 35 to 80 × 5 to 9 μm, composed of foot-cells, 20 to 35 × 5 to 9 µm, straight to usually curved or flexuous-sinuous at the base, followed by two to three shorter cells. Conidia were solitary, ellipsoid to oblong-elliptical, smooth, and 24 to 37 × 13 to 16 μm without fibrosin bodies. The teleomorph was not found on infected trees. These morphological characteristics were typical for anamorph of the genus Erysiphe (Braun and Cook 2012). To confirm fungal identification, the 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: MZ379159; LSU: MZ379160). BLAST analysis of sequences showed 99-100% similarity with Erysiphe elevata on Eucalyptus camaldulensis (LC177375), Catalpa bignonioides (MH638203), Tabernaemontana divaricata (MT802112), and Plumeria rubra (MH507182). Based on morphological and molecular analyses, the fungus was identified as E. elevata. To confirm pathogenicity, infected leaves were gently pressed onto the leaves of three healthy plants in separate pots, while three noninoculated plants were used as controls. All plants were maintained in a greenhouse at 25°C with a relative humidity of 65% to 70%. Disease symptoms were observed only on the inoculated plants after 10 days and the fungus was morphologically identical to that of the original infected leaves. Previously E. elevata has been reported on Catalpa spp. (Cook et al. 2006) from Europe, while E. camaldulensis (Meeboon and Takamatsu 2017), P. rubra (Wu et al. 2019; Yeh et al. 2019), and T. divaricata (Xu et al. 2021) have been reported as hosts from Thailand, Taiwan and China respectively. To our knowledge, this is the first report of powdery mildew caused by E. elevata on C. manghas in China and in the world. The disease would be a serious threat to ornamental plantings of C. manghas in China. References Braun, U., and Cook, R. T. A. 2012. Taxonomic Manual of the Erysiphales (Powdery Mildews). CBS Biodiversity Series No. 11. CBS, Utrecht, the Netherlands. Cook, R. T. A., et al. 2006. Mycol. Res. 110:672. Meeboon, J., and Takamatsu, S. 2017. Mycoscience 58:253. 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. Wu, H., et al. 2019. Plant Dis. 103:1035. Xu, D., et al. 2021. Plant Dis. 105:1203. Yeh, Y. W., et al. 2019. Plant Dis. 103:371.

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First Report of Myrothecium roridum Causing Leaf Spot on Zantedeschia aethiopica in China

Plant Disease ◽

10.1094/pdis-11-13-1140-pdn ◽

2014 ◽

Vol 98 (6) ◽

pp. 854-854 ◽

Cited By ~ 1

Author(s):

B.-J. Li ◽

H.-Y. Ben ◽

Y.-X. Shi ◽

X.-W. Xie ◽

A.-L. Chai

Keyword(s):

Leaf Spot ◽

Morphological Characteristics ◽

Its Region ◽

First Record ◽

Conidial Suspension ◽

Isolation And Identification ◽

Zantedeschia Aethiopica ◽

Calla Lily ◽

Initial Symptoms ◽

Myrothecium Roridum

Zantedeschia aethiopica (L.) Spreng. (calla lily), belonging to family Araceae, is a popular ornamental plant in China. In the summer of 2010, leaves of calla lily with typical symptoms of necrotic lesions were observed in a commercial glasshouse in Beijing, China (116°20′ E, 39°44′ N). The initial symptoms were circular to subcircular, 1 to 3 mm, and dark brown lesions on the leaf lamina. Under high humidity, lesions expanded rapidly to 5 to 10 mm with distinct concentric zones and produced black sporodochia, especially on the backs of leaves. Later, the infected leaves were developing a combination of leaf lesions, yellowing, and falling off; as a result, the aesthetic value of the plant was significantly impacted. Leaf samples were used in pathogen isolation. Symptomatic leaf tissues were cut into small pieces and surface sterilized with 70% ethanol for 30 s and then in 0.1% mercuric chloride solution for 1 to 3 min. After being washed in sterile distilled water three times, the pieces were plated on potato dextrose agar (PDA) and incubated at 25°C in darkness for 7 days (5). Initial colonies of isolates were white, floccose mycelium and developed dark green to black concentric rings that were sporodochia bearing viscid spore masses after incubating 5 days. Conidiophores branched repeatedly. Conidiogenous cells were hyaline, clavate, and 10.0 to 16.0 × 1.4 to 2.0 μm. Conidia were hyaline, cylindrical, both rounded ends, and 6.0 to 8.2 × 1.9 to 2.4 μm. Morphological characteristics of the fungus were consistent with the description of Myrothecium roridum Tode ex Fr. (3,4). To confirm the pathogenicity, three healthy plants of calla lily were inoculated with a conidial suspension (1 × 106 conidia per ml) brushed from a 7-day-old culture of the fungus. Control plants were sprayed with sterile water. The inoculated plants were individual with clear plastic bags and placed in a glass cabinet at 25°C. After 7 days, all inoculated leaves developed symptoms similar to the original samples, but control plants remained disease free. Re-isolation and identification confirmed Koch's postulates. For molecular identification, genomic DNA of a representative isolate (MTL07081001) was extracted by modified CTAB method (1), and the rDNA-ITS region was amplified by using primers ITS1 (5-TCCGTAGGTGAACCTGCGG-3) and ITS4 (5-TCCTCCGCTTATTGATATGC-3). The 465-bp amplicon (GenBank Accession No. KF761293) was 100% identity to the sequence of M. roridum (JF724158.1) from GenBank. M. roridum has an extensive host range, covering 294 host plants (2). To our knowledge, this is the first record of leaf spot caused by M. roridum on calla lily in China. References: (1) F. M. Ausubel et al. Current Protocols in Molecular Biology. John Wiley & Sons Inc, New York, 1994. (2) D. F. Farr and A. Y. Rossman, Fungal Databases. Syst. Mycol. Microbiol. Lab., ARS, USDA. Retrieved from http://nt.ars-grin.gov/fungaldatabases/ , October 2013. (3) M. T. Mmbaga et al. Plant Dis. 94:1266, 2010. (4) Y. X. Zhang et al. Plant Dis. 95:1030, 2011. (5) L. Zhu et al. J. Phytopathol. 161:59, 2013.

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Molecular and morphological evidence indicates that Pseudorhabdosynochus lantauensis (Monogenea: Diplectanidae) represents two species

Parasitology ◽

10.1017/s0031182004007152 ◽

2005 ◽

Vol 130 (6) ◽

pp. 669-677 ◽

Cited By ~ 25

Author(s):

X. Y. WU ◽

N. B. CHILTON ◽

X. Q. ZHU ◽

M. Q. XIE ◽

A. X. LI

Keyword(s):

Sequence Data ◽

Phylogenetic Analyses ◽

Large Subunit ◽

Strong Support ◽

Morphological Characteristics ◽

Sufficient Evidence ◽

Bootstrap Support ◽

Morphological Evidence ◽

Lsu Rdna ◽

Epinephelus Coioides

Sequences of the first internal transcribed spacer (ITS-1) and the D1-D3 domains of the large subunit (LSU) of the ribosomal DNA (rDNA) were determined for multiple specimens of 4 operational taxonomic units (OTUs) of the monogenean, Pseudorhabdosynochus lantauensis. OTUs were defined based on their collecting localities, host and/or morphological characteristics. All P. lantauensis specimens of one group (OTUs 1 and 3) differed in their sequences of the ITS-1 and partial LSU rDNA when compared with specimens of a second group (OTUs 2 and 4) by 12% and 2%, respectively. Results of the phylogenetic analyses of the LSU rDNA sequence data showed total (100%) bootstrap support for the separation of P. lantauensis into 2 distinct clades. At least 11 of the 18 nucleotide differences in the LSU sequence between the two P. lantauensis clades were derived (i.e. autapomorphic) characters when the morphologically distinct species, P. epinepheli and P. coioidesis, were used as outgroups. Furthermore, there were several autapomorphic character states for each P. lantauensis clade. This provides sufficient evidence to reject the null hypothesis that P. lantauensis represents a single species. Morphological and morphometric differences between these two clades provided additional strong support for the separation of P. lantauensis into two species. These two parasite species were found to co-exist on one of the two species of serranid fish (i.e. Epinephelus coioides) examined in the South China Sea (Guangdong Province, China).

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Nematodes associated with terrestrial slugs from canola fields and ornamental nurseries in South Africa

Zootaxa ◽

10.11646/zootaxa.4312.1.12 ◽

2017 ◽

Vol 4312 (1) ◽

pp. 194 ◽

Cited By ~ 3

Author(s):

ANNIKA PIETERSE ◽

ANTOINETTE P. MALAN ◽

LAURA M. KRUITBOS ◽

WILLEM SIRGEL ◽

JENNA L. ROSS

Keyword(s):

South Africa ◽

Sequence Data ◽

Large Subunit ◽

Morphological Characteristics ◽

Nematode Species ◽

First Record ◽

Small Subunit ◽

Western Cape ◽

Molecular Sequence Data ◽

Molecular Sequence

A survey of nematodes that use terrestrial slugs as definitive hosts, was conducted in canola fields and ornamental nurseries located in the Western Cape province of South Africa. A total of 3290 slugs were collected from 22 different sites. On the identification of the slugs, they were vivisected and examined for internal nematodes. After identifying the nematodes found, on the basis of their morphological characteristics, their identity was confirmed using molecular sequence data for the internal transcribed spacer (ITS-1, 5.8S, ITS-2), D2-D3 expansion segments of the large subunit (LSU or 28S) and small subunit (SSU or 18S) ribosomal DNA. Of the 22 sites investigated, 13 had nematodes present, with 8 % of the slugs being found to be infected with nematodes. Seven nematode species were confirmed, including Agfa flexilis, Angiostoma margaretae, Angiostoma sp. (SA1), Caenorhabditis elegans, mermithid sp. (SA1), Phasmarhabditis sp. (SA3) and Phasmarhabditis sp. (SA4). In addition, several Angiostoma spp. were also isolated, but could only be identified to genus level due to limited material. Of the seven confirmed species, four were previously undescribed. This is the first record of A. margaretae associating with Deroceras panormitanum, Deroceras reticulatum, Lehmannia valentiana and Oopelta polypunctata. Also, this is the first time that a mermithid has been found associating with molluscs in South Africa.

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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 Powdery Mildew Caused by Phyllactinia actinidiae on Hardy Kiwi in Korea

Plant Disease ◽

10.1094/pdis-04-14-0414-pdn ◽

2014 ◽

Vol 98 (10) ◽

pp. 1436-1436 ◽

Cited By ~ 1

Author(s):

S. E. Cho ◽

J. H. Park ◽

S. K. Lee ◽

S. H. Lee ◽

C. K. Lee ◽

...

Keyword(s):

Powdery Mildew ◽

Morphological Characteristics ◽

Northern China ◽

First Record ◽

Potential Threat ◽

Powdery Mildews ◽

Small Fruit ◽

Abaxial Leaf Surface ◽

Voucher Specimens ◽

Basal Septum

Actinidia arguta (Siebold & Zucc.) Planch. ex Miq., known as hardy kiwi, is a perennial vine native to Japan, Korea, northern China, and Russian Siberia. It produces a small fruit resembling the kiwifruit. The fruits, referred to as hardy kiwifruit, are edible and often sweeter than kiwifruit. Picking of wild hardy kiwifruits in autumn is a popular ecotourism activity in Korea. In 2000, a powdery mildew disease on the abaxial surface of hardy kiwi leaves was found in Korea. Additional findings of the powdery mildew between 2000 and 2013 showed that the disease of hardy kiwi commonly occurs in Korea. The infected leaves were frequently distorted when young, then becoming prematurely chlorotic and defoliated. Chasmothecia were abundantly formed by September. Voucher specimens (n = 21) were deposited in the Korea University Herbarium (KUS). Mycelia were hypophyllous, thinly effuse, initially forming patches, finally covering the whole abaxial leaf surface. Hyphal appressoria were hook-shaped or often branched, and single or opposite in pairs. Conidiophores were erect, cylindrical, 160 to 300 × 5 to 7.5 μm with straight foot-cells (65 to 115 μm long), basal septum elevated up to 15 μm, and produced conidia singly. Conidia were obpyriform to clavate, papillate at the apex, 55 to 75 × 20 to 32 μm, and devoid of fibrosin bodies. Germ tubes were produced at the terminal and lateral positions of conidia. Chasmothecia were blackish brown, depressed globose, and 190 to 250 μm in diameter. Appendages arising around the equatorial zone of chasmothecia were 9 to 15 in number, acicular with a bulbose base, 1 to 1.3 times as long as the chasmothecial diameter, hyaline throughout, and aseptate. Penicillate cells crowded on the upper part of the chasmothecia were ampulliform, numerous, 50 to 87.8 μm long, and 12.5 to 17.5 μm wide. Asci were 13 to 20 in a chasmothecium, olivaceous brown, 60 to 90 × 22.5 to 40 μm, and short stalked. Ascospores were 2 in an ascus, ellipsoid-ovoid, pale olivaceous, and 32.5 to 40 × 16.5 to 20 μm. On the basis of the morphological characteristics, this fungus was identified as Phyllactinia actinidiae (Jacz.) Bunkina (1). To confirm the identification, the complete internal transcribed spacer (ITS) regions of rDNA of three specimens (KUS-F23673, F26240, and F26308) were amplified using primers ITS5/P3 and sequenced (4). The resulting sequences were deposited in GenBank (Accession Nos. KJ703014, KJ703015, and KJ703016). GenBank BLAST search with the three isolates showed >99% similarity with the results for P. actinidiae on hardy kiwi from Japan (AB080489, AB080500, and AB080508). Actinidia-Phyllactinia associations were recorded in China, Japan, Taiwan, Korea, Russia, and Turkey (2,3). However, P. actinidiae on A. arguta was known only from Japan (3). To our knowledge, this is the first record of P. actinidiae on hardy kiwi in Korea. There has been no finding of powdery mildews on commercial varieties of golden kiwi (A. chinensis) and fuzzy kiwi (A. deliciosa) in Korea. Common occurrence of Phyllactinia powdery mildew on hardy kiwi in Korea can be a potential threat to the commercial kiwi 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. Erper et al. Scand. J. Forest Res. 27:432, 2012. (3) D. F. Farr and A. Y. Rossman. Fungal Databases. Syst. Mycol. Microbiol. Lab., Online publication. ARS, USDA, March 10, 2014. (4) S. Takamatsu et al. Mycol. Res. 113:117, 2009.

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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.

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Occurrence of Leaf Spot Caused by Mycocentrospora acerina on Zhujieshen(Panax japonicus C. A. Mey.) in China

Plant Disease ◽

10.1094/pdis-08-21-1718-pdn ◽

2021 ◽

Author(s):

Jingmao You ◽

Tao Tang ◽

Fanfan Wang ◽

Jie Guo ◽

Yuanyuan Duan ◽

...

Keyword(s):

Leaf Spot ◽

Large Subunit ◽

Morphological Characteristics ◽

Leaf Tissue ◽

Peat Moss ◽

Single Spore ◽

Agar Disc ◽

Ambient Lighting ◽

Initial Symptoms ◽

Panax Japonicus

Panax japonicus C. A. Mey., known as Japanese ginseng or “Zhujieshen” in China, is a perennial medicinal herb (family Araliaceae) native to China and is widely grown in many provinces including Hubei, Hunan, and Sichuan. In recent years, cultivation of Japanese ginseng has increased tremendously in China because of its high value. Its root is widely used in traditional Chinese medicine for the treatment of inflammation. In early May 2020, severe necrotic lesions on leaves with 40 to 50 % disease incidences were observed on 3-year-old Japanese ginseng plants in a cultivated field in Xuanen County (30°05′N, 109°83′E), Hubei Province, China. The total area affected by the disease was approximately 30 ha. Initial symptoms showed small, circular, brown, necrotic spots uniformly distributed on leaves. The center of the spots was light tan, surrounded by a dark brown ring and a chlorotic halo. As the disease progressed, multiple lesions merged into large disease spots with visible white fungal hyphae, causing leaf wilting. Ten small pieces (0.1 × 0.1 cm in size) of leaf tissue were removed from the lesion margins, surface-sterilized with 0.5 % sodium hypochlorite for 1 min and 75 % alcohol for 20 s, washed with sterile distilled water three times, dried, and placed on Petri plates with potato dextrose agar (PDA) medium containing 10 µg/ml of ampicillin and incubated at 20 °C for 5 days. Colonies with dense mycelia were initially white and gradually becoming black. The hyphae were septate, branched, and 3 to 7 µm in width. Conidiophores were flexuous, not branched, and produced a single spore. Spores (ranged from 95.4 to 255.5 × 6.2 to 13.5 μm) were elongate, multiseptate, with a long, strongly curved beak (ranged from 25.5 to 95.4 μm), The number of septae ranged from 4 to 13. Clamydospores with smooth or slightly rough wall were spherical to ovoid and averaged 8.5 to 25.4 × 7.2 to 16.5 μm. The six isolates were preliminarily identified as Mycocentrospora acerina (R. Hartig) Deightonbased on the morphological characteristics (Gilchrist et al. 2015). To confirm the identification, isolates ZJS1, ZJS3, and ZJS5 were chosen for DNA sequencing. The internal transcribed spacer (ITS) region of rDNA was amplified using the ITS1 and ITS4 primers (White et al. 1990) and sequenced. The identical sequences of the 491 bp amplicons were deposited in GenBank (accession no. ZJS1, MZ277314; ZJS3, OL333859; and ZJS5, OL333860). BLAST analysis of the sequences showed 100 % identity to M. acerina (MH856114). Moreover, the three isolates were further confirmed as M. acerina by amplifying the large subunit (LSU) of the ribosome gene (accession no. ZJS1, MZ277321; ZJS3, OL333861; and ZJS5, OL333862), as their identical sequences exhibited 99.83 % similarities with M. acerina (MH868490). Isolate ZJS1 was chosen to fulfill Koch’s postulates with 30 healthy 2-year-old P. japonicus grown in plastic pots filled with a sterilized mixture of peat moss and vermiculite (3:1). One leaf of each plant was inoculated with one 5-mm-diameter mycelium-agar disc and placed in a greenhouse at 20 ± 1 °C, with ambient lighting and relative humidity of 85 %. By 5 days after inoculation, all inoculated plants showed symptoms identical to those observed in the field, and no symptoms were observed on control plants. The fungus was reisolated from the inoculated plants and identified as M. acerina using the above method. The experiment was conducted thrice with similar results. To our knowledge, this is the first report of leaf spot caused by M. acerina on Japanese ginseng in China and the world. There is a need to develop effective management measures to reduce the occurrence of this disease.

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First Report of Powdery Mildew caused by Podosphaera xanthii on Euphorbia tithymaloides in Malaysia

Plant Disease ◽

10.1094/pdis-08-20-1700-pdn ◽

2020 ◽

Author(s):

Siti Izera Ismail ◽

Aziera Roslen

Keyword(s):

Powdery Mildew ◽

Sequence Data ◽

Morphological Characteristics ◽

Pathogenicity Test ◽

Podosphaera Xanthii ◽

Sequence Alignments ◽

Voucher Specimen ◽

First Report ◽

Initial Symptoms ◽

Young Leaves

Euphorbia tithymaloides L. (zig-zag plant) is a succulent, perennial shrub belonging to the Euphorbiaceae family and is widely cultivated in Malaysia for ornamental purposes and commercial values. In June 2019, typical symptoms of powdery mildew were observed on over 50% of the leaves of E. tithymaloides in a garden at Universiti Putra Malaysia, Serdang city of Selangor province, Malaysia. Initial symptoms included circular to irregular white powdery fungal colonies on both leaf surfaces and later covered the entire leaf surface. Severely infected leaves became necrotic, distorted and senesced. A voucher specimen Ma (PM001-Ma) was deposited in the Mycology laboratory, Faculty of Agriculture, UPM. Microscopic observation showed hyphae hyaline, branched, thin-walled, smooth, 3 to 6 µm wide with nipple-shaped appressoria. Conidiophores were straight, measured 30 to 90 μm long × 8 to 12 μm wide and composed of a cylindrical foot cell, 50 to 75 μm long. Conidia formed in chains were hyaline, ellipsoid to oval with fibrosin bodies, measured 25 to 36 × 16 to 20.1 μm in size and chasmothecia were not observed on the infected leaves. Genomic DNA was directly isolated from mycelia and conidia of isolate Ma using DNeasy Plant Mini Kit (Qiagen, USA). The universal primer pair ITS4/ITS5 of rDNA (White et al. 1990) was used for amplification and the resulting 569-bp sequence was deposited in GenBank (Accession no. MT704550). A BLAST nucleotide search revealed 100% similarity with that of Podosphaera xanthii on Momordica charantia wild from Taiwan (Accession no. KM505135) (Kirschner and Liu 2015). Both the morphological characteristics of the anamorph and ITS sequence data support the identification of this powdery mildew on E. tithymaloides as Podosphaera xanthii (Castagne) U. Braun & Shishkoff (Braun and Cook 2012). A pathogenicity test was conducted by gently pressing the infected leaves onto young leaves of five healthy potted plants. Five noninoculated plants were used as controls. The inoculated plants were maintained in a greenhouse at 25 ± 2°C and the test was repeated. Seven days after inoculation, white powdery symptoms were observed similar to those on the naturally infected leaves, while control plants remained asymptomatic. The fungus on the inoculated leaves was morphologically and molecularly identical to the fungus on the original specimens. Sequence alignments were made using MAFFT v.7.0 (Katoh et al. 2019) and a maximum likelihood phylogram was generated by MEGA v.7.0 (Kumar et al. 2016). Isolate Ma grouped in a strongly supported clade (100% bootstrap value) with the related species of P. xanthii available in GenBank based on the ITS region. Powdery mildew caused by P. xanthii has been reported as a damaging disease that can infect a broad range of plants worldwide (Farr and Rossman 2020). It also has been recently reported on Sonchus asper in China (Shi et al. 2020). According to our knowledge, this is the first report of powdery mildew caused by P. xanthii on E. tithymaloides worldwide. The occurrence of powdery mildew on E. tithymaloides could pose a serious threat to the health of this plant, resulting in death and premature senescence of young leaves.

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First Report of Powdery Mildew on Leucophyllum frutescens Caused by Podosphaera xanthii in Mexico

Plant Disease ◽

10.1094/pdis-06-20-1368-pdn ◽

2020 ◽

Author(s):

Hugo Beltrán-Peña ◽

Ruben Felix-Gastelum ◽

Moises Camacho-Tapia ◽

Kamila C. Correia ◽

Gabriel Herrera-Rodriguez ◽

...

Keyword(s):

Powdery Mildew ◽

Urban Areas ◽

Disease Incidence ◽

Phylogenetic Analyses ◽

Morphological Characteristics ◽

Podosphaera Xanthii ◽

Monitoring And Control ◽

Voucher Specimen ◽

First Report ◽

Initial Symptoms

Leucophyllum frutescens (Scrophulariaceae family), commonly known as Texas sage or cenizo, is an evergreen shrub native to southwestern United States and northern Mexico. This plant is commercially sold as a native, drought-tolerant ornamental. During the spring of 2019 and 2020, typical symptoms of powdery mildew were found on cenizo plants growing as ornamentals in urban areas in the municipality of Ahome, Sinaloa, Mexico. Disease incidence was 95% from a sampled population of 120 plants. Initial symptoms of powdery mildew developed as irregular white colonies on upper leaf surfaces which expanded as infections progressed. In severe infections, leaves became distorted, exhibiting premature defoliation. Microscopic examination showed nipple-shaped appressoria. Conidiophores (n= 30) were hyaline, cylindrical, erect, 89.4 to 134.2 μm long, and forming catenescent conidia. Foot-cells were cylindrical, 35.7 to 65.3 × 10.2 to 13.5 μm, followed by 1–3 shorter cells. Conidia (n= 100) were hyaline, ellipsoid to ovoid, 27.9 to 40.5 × 13.8 to 18.9 μm, containing distinct fibrosin bodies. Germ tubes were simple to forked and laterally produced from the middle of conidia. Chasmothecia were not found during the sampling period on the infected leaves. Based on morphological characteristics, the fungus was identified as Podosphaera xanthii (Braun and Cook 2012). A voucher specimen (accession no. FAVF219) was deposited in the Herbarium of the Faculty of Agronomy of El Fuerte Valley at the Autonomous University of Sinaloa (Juan Jose Rios, Sinaloa, Mexico). To further confirm the identification, total DNA was extracted, and the internal transcribed spacer (ITS) region was amplified by PCR using the primers ITS5/ITS4 (White et al. 1990) and sequenced. The resulting 503 bp sequence (GenBank accession no. MT624793) had 100% coverage and 100% identity to those of P. xanthii (MT568609–MT568611, MT472035, MT309699, MT250855, MT242593). A phylogenetic tree using the maximum parsimony (MP) and maximum likelihood (ML) methods and including published ITS sequences for Podosphaera species was obtained. Phylogenetic analyses revealed that ITS sequence from FAVF219 isolate was grouped into a clade with P. xanthii. Pathogenicity was demonstrated by gently dusting conidia from infected leaves onto 50 leaves of five healthy plants. Five non-inoculated plants served as controls. All plants were covered with polyethylene bags for 48 h to maintain high humidity and were maintained in a greenhouse at temperatures ranging from 20 to 35ºC. All inoculated plants developed similar symptoms to the original observations after 19 days, whereas no symptoms of powdery mildew were observed on control plants. The fungus present on the inoculated plants was morphologically identical to that originally observed on diseased plants, fulfilling Koch’s postulates. This fungus has been reported infecting members of the Cucurbitaceae in Mexico (Félix-Gastélum et al. 2017; Farr and Rossman 2020). However, to our knowledge, this is the first report of P. xanthii causing powdery mildew on a member of Scrophulariaceae, specifically L. frutescens in Mexico and worldwide. Further studies for monitoring and control strategies of powdery mildew on Texas sage are required.

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First Report of White Rust Caused by Albugo tragopogonis on Sunflower in Belgium

Plant Disease ◽

10.1094/pd-90-0379a ◽

2006 ◽

Vol 90 (3) ◽

pp. 379-379 ◽

Cited By ~ 4

Author(s):

C. Crepel ◽

S. Inghelbrecht ◽

S. G. Bobev

Keyword(s):

Morphological Characteristics ◽

Pathogenic Fungi ◽

First Record ◽

Cut Flowers ◽

Abaxial Surface ◽

Adaxial Surface ◽

White Rust ◽

Initial Symptoms ◽

Pathogenicity Tests ◽

Stem Lesions

Sunflower (Helianthus annuus) is widely used for cut flowers and decoration in Belgium. A serious outbreak of what was suspected to be white rust on sunflower was observed in an East Flemish nursery near the city of Ghent in August 2004. This disease has previously been reported in Europe (southwest of France) (1) and other parts of the world with losses as much as 70 to 80% (Australia, North and South America, and Africa) (2,3). In the Flemish nursery, only single diseased plants (cv. Sunrich) were found. Blister-like pustules containing sporangia were observed on infected leaves. Initially the blisters were pale green to yellow on the abaxial surface and white on the adaxial surface of the leaves. As the disease progressed, white pustules that formed on the adaxial surface of the leaves slowly turned yellow, and the blisters on the abaxial surface became yellow to orange and necrotic in the center. Finally, the pustules coalesced and the leaves withered. Stem lesions were not observed. Short, cylindrical to spherical-cuboid sporangia, recovered from the pustules on the adaxial surface of leaves, measured between 17.5 and 22.5 μm, with an average of 20.2 μm. Sporangial dimensions were similar to those of Albugo tragopogonis (Pers.) S.F. Gray (1). Inoculations were done by spraying a suspension of 1 × 105 sporangia per ml prepared by scraping pustules from naturally infected leaves. Leaves on three 2-month-old healthy plants were sprayed with this inoculum and three plants sprayed with distilled water served as controls. The plants were kept for 48 h under a humid chamber and subsequently at room temperature (20 to 25°C) on the laboratory bench. Initial symptoms of white rust were observed 12 to 14 days after inoculation. On the basis of symptoms, morphological characteristics, and pathogenicity tests, the pathogen was identified as A. tragopogonis. To our knowledge, this is the first record of A. tragopogonis on H. annuus in Belgium. References: (1) K. G. Mukerji. Description of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, England, UK, 1976. (2) A. Pernaud and A. Perny, Phytoma 471:43, 1995. (3) P. S. van Wyk et al. Helia 22:83, 1999.

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