First Report of Powdery Mildew Caused by Erysiphe macleayae on Macleaya microcarpa in Poland

Macleaya microcarpa (Maxim.) Fedde, also known as smallfruit plume poppy, is a perennial herb belonging to the family Papaveraceae. The plant, together with the better-known species M. cordata (Willd.) R. Br., is native to central China and is now planted worldwide for medicinal purposes. In October 2008 and August 2009, dozens of smallfruit plume poppy planted in the Kraków Botanical Garden, Poland, were found to be severely infected with a powdery mildew. White colonies with abundant sporulation developed on both sides of leaves and young stems, forming circular to irregular patches. Infections caused leaf yellowing and premature defoliation. The damage has been observed every year since 2009. Representative voucher specimens were deposited in the fungal herbarium of the W. Szafer Institute of Botany of the Polish Academy of Sciences (KRAM) and the Korea University herbarium (KUS). Appressoria on the mycelia were lobed, often in pairs. Conidiophores composed of three to four cells arose from the upper part of creeping hyphae, 65 to 120 × 7 to 10 μm, attenuated toward the base, sub-straight or slightly flexuous in foot-cells, and produced conidia singly. Conidia were hyaline, oblong-elliptical to doliiform, 25 to 38 × 12 to 18 μm with a length/width ratio of 1.8 to 2.6; lacked fibrosin bodies; and produced germ tubes on the subterminal position with club-shaped or lobed appressoria. The conidial surface was wrinkled to irregularly reticulate. No chasmothecia were found. The structures described above match well with the anamorph of Erysiphe macleayae R.Y. Zheng & G.Q. Chen (3). To confirm the identity of the causal fungus, the internal transcribed spacer (ITS) region of rDNA from KUS-F24459 was amplified using primers ITS5 and P3 (4) and directly sequenced. The resulting sequence of 553 bp was deposited in GenBank (Accession No. JQ681217). A GenBank BLAST search using the present data revealed >99% sequence similarity of the isolate with E. macleayae on M. cordata from Japan (AB016048). Pathogenicity was confirmed through inoculation by gently pressing diseased leaves onto leaves of three healthy potted plants. Three noninoculated plants served as controls. Plants were maintained in a greenhouse at 25°C. Inoculated plants developed signs and symptoms after 7 days, whereas the control plants remained healthy. The fungus present on the inoculated plants was morphologically identical to that originally observed on diseased plants. The powdery mildew infections of M. cordata associated with E. macleayae have been recorded in China and Japan (2), and more recently in Germany (1,3). To our knowledge, this is the first report of E. macleayae on M. microcarpa globally as well as in Poland. This mildew species was described in China and is endemic to Asia, where chasmothecia of the fungus were found. Only recently have powdery mildews been found on M. cordata in Germany (1,3) and now on M. microcarpa in Poland, indicating the fungus is spreading in Europe. References: (1) N. Ale-Agha et al. Schlechtendalia 17:39, 2008. (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/ , February 7, 2012. (3) A. Schmidt and M. Scholler. Mycotaxon 115:287, 2011. (4) S. Takamatsu et al. Mycol. Res. 113:117, 2009.

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

Plant Disease ◽

10.1094/pdis-94-1-0130c ◽

2010 ◽

Vol 94 (1) ◽

pp. 130-130 ◽

Cited By ~ 4

Author(s):

M. Troisi ◽

D. Bertetti ◽

A. Garibaldi ◽

M. L. Gullino

Keyword(s):

Powdery Mildew ◽

Signs And Symptoms ◽

Its Region ◽

The United States ◽

Plant Diseases ◽

Gerbera Jamesonii ◽

First Report ◽

Potted Plants ◽

Golovinomyces Cichoracearum ◽

Blastn Analysis

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

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First Report of Powdery Mildew Caused by Oidium hortensiae on Mophead Hydrangea in Korea

Plant Disease ◽

10.1094/pdis-03-12-0300-pdn ◽

2012 ◽

Vol 96 (7) ◽

pp. 1072-1072 ◽

Cited By ~ 3

Author(s):

M. J. Park ◽

S. E. Cho ◽

J. H. Park ◽

S. K. Lee ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Sequence Data ◽

Morphological Characteristics ◽

Signs And Symptoms ◽

Its Region ◽

Polyethylene Film ◽

Width Ratio ◽

First Report ◽

Close Phylogenetic Relationship ◽

Powdery Mildew Disease

Hydrangea macrophylla (Thunb.) Ser., known as mophead hydrangea, is native to Japan and is used as a potted ornamental or is planted for landscaping in gardens worldwide. In May 2011, powdery mildew occurred on potted mophead hydrangea cv. Emerald plants in polyethylene-film-covered greenhouses in Icheon, Korea. Heavily infected plantings were unmarketable, mainly due to purplish red discoloration and crinkling of leaves. Such powdery mildew symptoms on mophead hydrangea in gardens had been often found in Korea since 2001, and the collections (n = 10) were deposited in the Korea University herbarium (KUS). In all cases, there was no trace of chasmothecia formation. Mycelium was effuse on both sides of leaves, young stems, and flower petals. Appressoria were well developed, lobed, and solitary or in opposite pairs. Conidiophores were cylindrical, 70 to 145 × 7.5 to 10 μm, and composed of three to four cells. Foot-cells of conidiophores were straight to sub-straight, cylindric, short, and mostly less than 30 μm long. Conidia produced singly were ellipsoid to oval, 32 to 50 × 14 to 22 μm with a length/width ratio of 1.7 to 2.8, lacked fibrosin bodies, and showed angular/rectangular wrinkling of outer walls. Germ tubes were produced on the perihilar position of conidia. Primary conidia were apically conical, basally rounded to subtruncate, 32 to 42 × 14 to 18 μm, and thus generally smaller than the secondary conidia. The morphological characteristics are consistent with previous descriptions of Oidium hortensiae Jørst. (3,4). To confirm the identification, the complete internal transcribed spacer (ITS) region of rDNA from KUS-F25514 was amplified with primers ITS5 and P3 and directly sequenced. The resulting sequence of 694 bp was deposited in GenBank (Accession No. JQ669944). There was no ITS sequence data known from powdery mildews on Hydrangea. Therefore, this is the first sequence of O. hortensiae submitted to GenBank. Nevertheless, a GenBank BLAST search of this sequence showed >99% similarity with those of Oidium spp. recorded on crassulacean hosts (e.g. GenBank Accession Nos. EU185641 ex Sedum, EU185636 ex Echeveria, and EU185639 ex Dudleya) (2), suggesting their close phylogenetic relationship. Pathogenicity was confirmed through inoculation by gently pressing diseased leaves onto leaves of five healthy potted mophead hydrangea cv. Emerald plants. Five noninoculated plants of the same cultivar served as controls. Plants were maintained in a greenhouse at 22 ± 2°C. Inoculated plants developed signs and symptoms after 6 days, whereas the control plants remained healthy. The fungus present on the inoculated plants was morphologically identical to that originally observed on diseased plants, fulfilling Koch's postulates. Occurrence of powdery mildew disease on mophead hydrangea is circumglobal (1). To our knowledge, this is the first report of powdery mildew disease caused by O. hortensiae on mophead hydrangea in Korea. Powdery mildew infections in Korea pose a serious threat to the continued production of quality potted mophead hydrangea in polyethylene-film-covered greenhouses. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases, Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved March 19, 2012, from http://nt.ars-grin.gov/fungaldatabases/ . (2) B. Henricot. Plant Pathol. 57:779, 2008. (3) A. Schmidt and M. Scholler. Mycotaxon 115:287, 2011. (4) S. Tanda. J. Agric. Sci. Tokyo Univ. Agric. 43:253, 1999.

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First Report of Powdery Mildew Caused by Golovinomyces sonchicola on Ixeris chinensis in Korea

Plant Disease ◽

10.1094/pdis-11-13-1132-pdn ◽

2014 ◽

Vol 98 (7) ◽

pp. 999-999 ◽

Cited By ~ 2

Author(s):

J. K. Choi ◽

B. S. Kim ◽

S. H. Hong ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Sequence Similarity ◽

Folk Medicine ◽

Morphological Characteristics ◽

Its Region ◽

Width Ratio ◽

Lateral Part ◽

Potential Threat ◽

First Report ◽

Powdery Mildews

Ixeris chinensis (Thunb.) Nakai, known as Chinese ixeris, is distributed from Siberia to Japan, including Korea, Taiwan, and China. The whole plant has been used in folk medicine in Asia (4). In Korea, the plants of Chinese ixeris have been gathered and used as a wild root vegetable. During summer to autumn of 2011, Chinese ixeris leaves were found to be heavily infected with a powdery mildew in several locations of Korea. Symptoms first appeared as thin white colonies, which subsequently developed into abundant hyphal growth on both sides of the leaves, leading to drying of the leaves. The same symptoms on Chinese ixeris leaves were continuously observed in 2012 and 2013. Voucher specimens (n = 10) were deposited at Korea University Herbarium (KUS). Hyphal appressoria were moderately lobed or nipple-shaped. Conidiophores arose from the lateral part of the hyphae, measured 100 to 270 × 10 to 12.5 μm, and produced 2 to 6 immature conidia in chains with a sinuate outline. Basal parts of foot-cells in conidiophores were curved. Conidia were barrel-shaped to ellipsoid, measured 26 to 36 × 13 to 19 μm (length/width ratio = 1.7 to 2.4), lacked fibrosin bodies, and showed reticulate wrinkling of the outer walls. Primary conidia were ovate with conical-obtuse apex and subtruncate base. Germ tubes were produced on the perihilar position of conidia. Chasmothecia were not observed. The morphological characteristics were typical of the Euoidium type anamorph of the genus Golovinomyces, and the fungus measurements and structures were consistent with those of G. sonchicola U. Braun & R.T.A. Cook (1). To confirm the identification, internal transcribed spacer (ITS) region of rDNA sequences from a representative material (KUS-F26212) was amplified using primers ITS5/P3 and sequenced (3). The resulting 416-bp sequence was deposited in GenBank (Accession No. KF819857). A GenBank BLAST search revealed that the isolate showed >99% sequence similarity with those of G. cichoracearum from Sonchus spp. (e.g., AB453762, AF011296, JQ010848, etc.). G. sonchicola is currently confined to G. cichoracearum s. lat. on Sonchus spp., based on molecular sequence analyses (1). Pathogenicity was confirmed through inoculation by gently pressing a diseased leaf onto leaves of five healthy potted Chinese ixeris. Five non-inoculated plants served as controls. Inoculated plants developed symptoms after 6 days, whereas the controls remained symptomless. The fungus present on the inoculated plants was identical morphologically to that originally observed on diseased plants. Powdery mildew infections of I. chinensis associated with Golovinomyces have been known in China (2). To our knowledge, this is the first report of powdery mildew disease caused by G. sonchicola on I. chinensis in Korea. Farming of Chinese ixeris has recently started on a commercial scale in Korea. Though no statistical data are available, we postulate the cultivation area in Korea to be approximately 200 ha, mostly growing without chemical controls. Occurrence of powdery mildews poses a potential threat to safe production of this vegetable, especially in organic farming. 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) F. L. Tai. Bull. Chinese Bot. Sci. 2:16, 1936. (3) S. Takamatsu et al. Mycol. Res. 113:117, 2009. (4) S. J. Zhang et al. J. Nat. Prod. 69:1425, 2006.

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First Confirmed Report of Powdery Mildew Caused by Podosphaera xanthii on Farfugium japonicum in Korea

Plant Disease ◽

10.1094/pdis-11-12-1069-pdn ◽

2013 ◽

Vol 97 (5) ◽

pp. 691-691 ◽

Cited By ~ 1

Author(s):

S. E. Cho ◽

M. J. Park ◽

C. H. Shin ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Signs And Symptoms ◽

Its Region ◽

Lateral Position ◽

Width Ratio ◽

Podosphaera Xanthii ◽

Potted Plants ◽

Ampelomyces Quisqualis ◽

Young Leaves ◽

Farfugium Japonicum

Farfugium japonicum (L.) Kitam., known as Japanese silver leaf, is native to Japan, Korea, and Taiwan. It is grown as an ornamental plant for garden plantings and containers not only in East Asia but more recently also in Europe and North America. Since 2003, powdery mildew infections of F. japonicum ‘Gigantea’ have been consistently found in the southern part of Korea, including the districts of Jeju, Seogwipo, Busan, Wando, and Ulleungdo. Specimens have been deposited in the Korea University Herbarium (KUS). Signs of powdery mildew first appeared as circular to irregular white patches on both sides of the leaves. The infections were usually severe on young leaves and caused malformation and browning. Appressoria on the mycelium were nipple-shaped or nearly absent. Conidiophores, measuring 160 to 280 × 10 to 12.5 μm, were simple and produced 2 to 12 immature conidia in chains, followed by 2 to 3 cells. Foot-cells in conidiophores were relatively short, 50 to 95 μm long, and constricted at the base. Conidia were hyaline, ellipsoid to ovate, 32 to 48 × 17.5 to 25 μm (length/width ratio = 1.4 to 2.3), had distinct fibrosin bodies, and produced germ tubes on the lateral position. No chasmothecia were observed. The morphology and dimentions of reproductive structures were compatible with those of Podosphaera xanthii (Castagne) U. Braun & Shishkoff (1). To confirm the identity of the causal fungus, the complete ITS region of rDNA from isolate KUS-F26469 was amplified with primers ITS5 and P3 (4) and directly sequenced. The resulting sequence of 475 bp was deposited in GenBank (Accession No. KC155426). A GenBank BLAST search of this sequence revealed 100% identity (475/475 bp) with those of many P. fusca isolates on plants in the Aster family plants including Calendula officinalis, Euryops pectinatus, Syneilesis palmata, and F. japonicum from Japan (e.g., AB040346). The P. fusca isolates listed above are now placed in P. xanthii (1). Pathogenicity was confirmed through inoculation by gently pressing diseased leaves onto leaves of three healthy potted plants of the same cultivar. Three non-inoculated plants served as controls. Plants were maintained in a greenhouse at 25 ± 2°C. Inoculated plants developed typical signs and symptoms of powdery mildew after 8 days, whereas the control plants remained symptomless. The fungus present on the inoculated leaves was morphologically identical to that originally observed on diseased plants. Powdery mildew infections of F. japonicum caused by P. fusca (syn. P. fuliginea) have been reported previously in both Japan and Korea (2). In Korea, it was listed simply as a host fungus of Ampelomyces quisqualis, which is hyperparasitic to powdery midlews, without any data on its identity (3). To our knowledge, this is the first confirmed report of powdery mildew caused by P. xanthii on F. japonicum in Korea. 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 November 14, 2012. (3) M. J. Park et al. Fungal Biol. 114:235, 2010. (4) S. Takamatsu et al. Mycol. Res. 113:117, 2009.

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First Report of Powdery Mildew Caused by Erysiphe heraclei on Chervil in Korea

Plant Disease ◽

10.1094/pdis-07-13-0797-pdn ◽

2014 ◽

Vol 98 (3) ◽

pp. 426-426

Author(s):

K. S. Han ◽

S. E. Cho ◽

J. H. Park ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Morphological Characteristics ◽

Signs And Symptoms ◽

Its Region ◽

The United States ◽

Control Treatment ◽

Width Ratio ◽

Anethum Graveolens ◽

First Report ◽

Powdery Mildews

Chervil (Anthriscus cerefolium (L.) Hoffm.), belonging to the family Apiaceae, is an aromatic annual herb that is native to the Caucasus. It is widely used as a flavoring agent for culinary purposes. This herb was recently introduced in Korea. In April 2013, plants showing typical symptoms of powdery mildew disease were observed in a polyethylene film-covered greenhouse in Seoul, Korea. White mycelium bearing conidia formed irregular patches on leaves and stems. Mycelial growth was amphigenous. Severe infections caused leaf withering and premature senescence. Voucher specimens were deposited in the Korea University Herbarium (KUS). Hyphae were septate, branched, with moderately lobed appressoria. Conidiophores presented 3 to 4 cells and measured 85 to 148 × 7 to 9 μm. Foot-cells of conidiophores were 37 to 50 μm long. Conidia were produced singly, oblong-elliptical to oblong, measured 30 to 50 × 13 to 18 μm with a length/width ratio of 2.0 to 3.3, lacked conspicuous fibrosin bodies, and with angular/rectangular wrinkling of the outer walls. Germ tubes were produced in the subterminal position of conidia. Chasmothecia were not found. These structures are typical of the powdery mildew Pseudoidium anamorph of the genus Erysiphe. The specific measurements and morphological characteristics were consistent with those of E. heraclei DC. (1). To confirm identity of the causal fungus, the complete internal transcribed spacer (ITS) region of rDNA of KUS-F27279 was amplified with primers ITS5 and P3 (4) and sequenced directly. The resulting 561-bp sequence was deposited in GenBank (Accession No. KF111807). A GenBank BLAST search of this sequence showed >99% similarity with those of many E. heraclei isolates, e.g., Pimpinella affinis (AB104513), Anethum graveolens (JN603995), and Daucus carota (EU371725). Pathogenicity was confirmed through inoculation by gently pressing a diseased leaf onto leaves of five healthy potted chervil plants. Five non-inoculated plants served as a control treatment. Plants were maintained in a greenhouse at 22 ± 2°C. Inoculated plants developed signs and symptoms after 6 days, whereas the control plants remained healthy. The fungus present on the inoculated plants was identical morphologically to that originally observed on diseased plants. Chervil powdery mildews caused by E. heraclei have been reported in Europe (Bulgaria, France, Germany, Hungary, Italy, Romania, Switzerland, and the former Soviet Union) and the United States (2,3). To our knowledge, this is the first report of powdery mildew caused by E. heraclei on chervil in Asia as well as in Korea. The plant is cultivated in commercial farms for its edible leaves in Korea. Occurrence of powdery mildew is a threat to quality and marketability of this herb, especially those grown in organic farming where chemical control options are limited. 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 July 29, 2013. (3) S. T. Koike and G. S. Saenz. Plant Dis. 88:1163, 2004. (4) S. Takamatsu et al. Mycol. Res. 113:117, 2009.

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

Plant Disease ◽

10.1094/pdis-11-20-2333-pdn ◽

2020 ◽

Author(s):

Mo Zhu ◽

Jie Ji ◽

Xiao Duan ◽

YongFang Li

Keyword(s):

Powdery Mildew ◽

Morphological Characteristics ◽

Signs And Symptoms ◽

Its Region ◽

Zinnia Elegans ◽

Width Ratio ◽

Post Inoculation ◽

First Report ◽

Golovinomyces Cichoracearum ◽

Length Width

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

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First Report of Powdery Mildew Caused by Erysiphe heraclei on Peucedanum japonicum in Korea

Plant Disease ◽

10.1094/pdis-09-14-0895-pdn ◽

2015 ◽

Vol 99 (1) ◽

pp. 161-161 ◽

Cited By ~ 1

Author(s):

I. Y. Choi ◽

S. H. Hong ◽

S. E. Cho ◽

J. H. Park ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Organic Farming ◽

Disease Incidence ◽

Morphological Characteristics ◽

Its Region ◽

Petroselinum Crispum ◽

Width Ratio ◽

First Report ◽

Potted Plants ◽

Powdery Mildews

Peucedanum japonicum Thunb., belonging to the family Apiaceae, is distributed in many Asian countries, including Korea. This plant was recently developed as an edible green and is cultivated under organic farming in Korea. In June 2013, plants showing typical symptoms of powdery mildew were found with approximately 50% disease incidence in polyethylene-film-covered greenhouses in Iksan City, Korea. Symptoms first appeared as circular white colonies, which subsequently showed abundant mycelial growth on the leaves, often covering the whole surface. Infected plants were unmarketable mainly due to signs of white fungal growths and reddish discoloration on the leaves. The same symptoms were found on P. japonicum in poly-tunnels in Iksan City and Jinan County of Korea in 2014. Voucher specimens (n = 3) were deposited in the Korea University Herbarium (KUS). Appressoria were lobed, and solitary or in opposite pairs. Conidiophores were cylindrical, 80 to 145 × 8 to 10 μm, and composed of three to four cells. Foot-cells of conidiophores were straight to substraight, cylindrical, and 25 to 63 μm long. Singly produced conidia were oblong-elliptical to oblong, occasionally ovate, 35 to 50 × 13 to 16 μm with a length/width ratio of 2.3:3.1, with angular/rectangular wrinkling of outer walls, and lacked distinct fibrosin bodies. Germ tubes were produced on the perihilar position of conidia. Primary conidia were apically conical, basally truncate, and generally smaller than the secondary conidia. No chasmothecia were found. These structures are typical of the powdery mildew Pseudoidium anamorph of the genus Erysiphe. The specific measurements and morphological characteristics were consistent with those of E. heraclei DC. (2). To confirm the identification, the complete internal transcribed spacer (ITS) region of rDNA from KUS-F27872 was amplified with primers ITS1/ITS4 and sequenced. The resulting 560-bp sequence was deposited in GenBank (Accession No. KM491178). The obtained ITS sequence shared >99% similarity with those of E. heraclei from apiaceous hosts, e.g., Daucus carota (KC480605), Pimpinella affinis (AB104513), and Petroselinum crispum (KF931139). Pathogenicity was confirmed through inoculation by gently dusting conidia onto leaves of five healthy potted plants. Five non-inoculated plants served as controls. Inoculated plants developed symptoms after 6 days, whereas the control plants remained symptomless. The fungus present on the inoculated plants was identical in morphology to those observed in the field. Powdery mildew of P. japonicum caused by E. heraclei has been reported in Japan (4), and numerous reports of E. heraclei on various species of Peucedanum plants have been made in most part of Europe and East Asia (Japan and far eastern Russia) (1,3). However, this is the first report of powdery mildew caused by E. heraclei on P. japonicum in Korea. Occurrence of powdery mildews is a threat to the quality and marketability of this plant, especially in organic farming. References: (1) K. Amano. Host Range and Geographical Distribution of the Powdery Mildew Fungi. Japan Scientific Societies Press, Tokyo, 1986. (2) U. Braun and R. T. A. Cook. Taxonomic Manual of the Erysiphales (Powdery Mildews), CBS Biodiversity Series No.11. CBS, Utrecht, 2012. (3) D. F. Farr and A. Y. Rossman. Fungal Databases, Syst. Mycol. Microbiol. Lab., online publication. ARS, USDA. Retrieved August 18, 2014. (4) S. Tanda and C. Nakashima. J. Agric. Sci., Tokyo Univ. Agric. 47:54, 2002.

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First Report of Powdery Mildew Caused by Erysiphe heraclei on Dill in Korea

Plant Disease ◽

10.1094/pdis-02-12-0118-pdn ◽

2012 ◽

Vol 96 (6) ◽

pp. 907-907 ◽

Cited By ~ 1

Author(s):

S. E. Cho ◽

J. H. Park ◽

J. Y. Kim ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Sequence Similarity ◽

Signs And Symptoms ◽

Its Region ◽

Anethum Graveolens ◽

First Report ◽

The Family ◽

Causal Fungus ◽

Voucher Specimens ◽

Germ Tubes

Dill (Anethum graveolens L.) is a scented herb belonging to the family Apiaceae. The plant has a long and ancient history in many countries as a culinary and medicinal herb. In October 2008, plants showing typical symptoms of powdery mildew disease were found in polythene tunnels in Icheon, Korea. Symptoms first appeared as thin white colonies, which subsequently showed abundant growth on the leaves and stems. Most diseased plantings were unmarketable and shriveled without being harvested. The damage caused by powdery mildew infections on dill has reappeared every year, with confirmation of the causal agent made again in 2011. Voucher specimens were deposited in the Korea University Herbarium (KUS). Hyphae were septate, branched, and 4 to 7 μm wide. Appressoria on the mycelium were multilobed or moderately lobed. Conidiophores were unbranched, cylindrical, 80 to 140 × 8 to 10 μm, straight or slightly flexuous in foot cells, and produced conidia singly, followed by two to three cells. Conidia were oblong elliptical to oblong, 28 to 50 × 14 to 18 μm, lacked fibrosin bodies, and produced germ tubes on the subterminal position, with angular/rectangular wrinkling of the outer walls. Primary conidia were apically conical, basally subtruncate, and generally smaller than the secondary conidia. No chasmothecia were found but the above characteristics are consistent with Erysiphe heraclei DC. (1). To confirm the identity of the causal fungus, the complete internal transcribed spacer (ITS) region of rDNA from isolate KUS-F26425 was amplified with primers ITS5 and P3 as described by Takamatsu et al. (3) and directly sequenced. The resulting 630-bp sequence was deposited in GenBank (Accession No. JQ517297). Comparison with the sequences available in the GenBank database revealed that the isolate showed >99% sequence similarity with those of E. heraclei from Pleurospermum camtschaticum (GU173850) and Daucus carota (EU371725). Pathogenicity was confirmed through inoculation by gently pressing diseased leaves onto leaves of five healthy potted dill plants. Five noninoculated plants served as controls. Plants were maintained in a greenhouse at 22 ± 2°C. Inoculated plants developed signs and symptoms after 7 days, whereas the control plants remained healthy. The fungus present on the inoculated plants was morphologically identical to that originally observed on diseased plants. Powdery mildew caused by E. heraclei on dill has been known worldwide where the plant is cultivated (2). In East Asia, however, dill powdery mildew was known only from Taiwan (4). To our knowledge, this is the first report of powdery mildew infections by E. heraclei on dill in Korea. Since cultivation of dill was only recently started on a commercial scale in Korea, powdery mildew infections pose a serious threat to safe production of this herb, especially in organic farming where chemical control would be prohibited. References: (1) U. Braun. Beih. Nova Hedw. 89:1, 1987. (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/ January 28, 2012. (3) S. Takamatsu et al. Mycol. Res. 113:117, 2009. (4) J. G. Tsay. Trans. Mycol. Soc. Repub. China 5:1, 1990.

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First Report of Powdery Mildew Caused by Podosphaera xanthii on Verbena brasiliensis in Korea

Plant Disease ◽

10.1094/pdis-02-14-0195-pdn ◽

2014 ◽

Vol 98 (8) ◽

pp. 1159-1159 ◽

Cited By ~ 2

Author(s):

S. E. Cho ◽

J. H. Park ◽

S. H. Hong ◽

B. S. Kim ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Morphological Characteristics ◽

Signs And Symptoms ◽

Its Region ◽

Lateral Position ◽

Jeju Island ◽

Width Ratio ◽

Indigenous Plants ◽

Poor Growth ◽

First Report

Verbena brasiliensis Vell., commonly known as Brazilian verbena, is native to South America and has been introduced into North America, coastal Europe, southern Africa, and Australasia. Though partly cultivated for garden use, it is invasive in riverine areas and also on roadsides, forest margins, pastures, and waste areas (4). In Korea, this plant was first reported in 1998 in Jeju Island and has become widely naturalized by replacing indigenous plants and disrupting native ecosystems in most of southern part of Korea (3). Since 2009, powdery mildew on Brazilian verbena has been consistently found in several locations of Busan City, Korea. Symptoms appeared as circular to irregular white patches, which subsequently showed abundant hyphal growth on both sides of the leaves and on stems. High disease severity caused poor growth of the plants, resulting in premature senescence and reduced flowering. Specimens (n = 5) were deposited in the Korea University Herbarium (KUS). Appressoria on the mycelium were nipple-shaped or nearly absent. Conidiophores were 140 to 190 × 11 to 12.5 μm and produced 2 to 7 immature conidia in chains with a crenate outline. Foot-cells in conidiophores were straight, cylindric, relatively short, 50 to 65 μm long, and constricted at the very base of branching point from the hypha. Conidia were hyaline, ellipsoid to ovate, measured 28 to 38 × 18.5 to 22 μm (length/width ratio of 1.2 to 1.8), and contained distinct fibrosin bodies. Germ tubes were produced from the lateral position of conidia. No chasmothecia were observed. These structures are typical of the powdery mildew Euoidium anamorph of the genus Podosphaera. The morphological characteristics and measurements were consistent with those of P. xanthii (Castagne) U. Braun & Shishkoff (1). To confirm the identity, the complete internal transcribed spacer (ITS) region of rDNA of the isolate KUS-F27220 was amplified with primers ITS1/ITS4, and sequenced. The resulting 477-bp sequence was deposited in GenBank (Accession No. KJ472787). A GenBank BLAST search of this sequence revealed 100% identity with Podosphaera sp. on V. bonariensis and V.× hybrida from Japan (AB462804 and AB040347). The Podosphaera sp. isolates listed above are now placed in P. xanthii (1). Pathogenicity was confirmed through inoculation by gently pressing a diseased leaf onto leaves of three healthy, potted 2-month-old Brazilian verbena plants. Three non-inoculated plants served as controls. Inoculated plants developed signs and symptoms after 6 days, whereas the control plants remained symptomless. The fungus present on the inoculated leaves was identical morphologically to that originally observed on diseased plants. Powdery mildew of Verbena spp. associated with Podosphaera sp. (including Sphaerotheca sp.) has been globally reported, but not on V. brasiliensis (1,2). To our knowledge, this is the first report of powdery mildew disease caused by P. xanthii on V. brasiliensis globally. Our field observations suggest that the powdery mildew could limit expansion of V. brasiliensis in Korea. 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 February 18, 2014. (3) C. G. Song and Y. H. Yang. The Naturalized Plants in Jeju Island. Nam-Jeju County, Jeju, Korea, 2005. (4) P. F. Yao. Kew Bull. 45:101, 1990.

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First Report of Powdery Mildew Caused by Erysiphe cruciferarum on Garden Cress in Korea

Plant Disease ◽

10.1094/pdis-01-13-0001-pdn ◽

2013 ◽

Vol 97 (7) ◽

pp. 998-998 ◽

Cited By ~ 1

Author(s):

J. K. Choi ◽

J. H. Kim ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Organic Farming ◽

Signs And Symptoms ◽

Its Region ◽

Lepidium Sativum ◽

Width Ratio ◽

Garden Cress ◽

First Report ◽

Two Samples ◽

Length Width

Garden cress (Lepidium sativum L.), belonging to the family Brassicaceae, is an edible herb with peppery flavor and aroma (2). This plant was recently introduced and is cultivated as an edible green under organic farming in Korea. In September 2012, seedlings showing typical symptoms of powdery mildew were found in greenhouses in Pyeongchang County, Korea. Symptoms first appeared as thin white colonies, which progressed to abundant growth on the leaves and stems. Infected herbs were unmarketable mainly due to signs of senescence and withering of leaves and mostly abandoned without becoming harvested. Two samples of diseased leaves were deposited in the Korea University Herbarium (KUS Accession Nos. F27137 and F27150). Appressoria on the mycelium were well-developed, lobed, and solitary or in opposite pairs. Conidiophores were unbranched, cylindrical, 88 to 120 × 8.5 to 10 μm, and composed of 3 to 4 cells. Foot-cells of conidiophores were straight to sub-straight, cylindric, 22 to 42 μm long, and generally equal to or shorter than the upper cells. Singly produced conidia were oblong to cylindrical or oval, 34 to 52 × 14 to 18 μm with a length/width ratio of 2.2 to 3.3, with angular/rectangular wrinkling of outer walls, and no distinct fibrosin bodies. Germ tubes were produced on the perihilar position of conidia. No chasmothecia were found. These structures are typical of the powdery mildew Pseudoidium anamorph of the genus Erysiphe. The specific measurements match with those of E. cruciferarum Opiz ex L. Junell as previously described (1). To confirm the identification, the complete internal transcribed spacer (ITS) region of rDNA from KUS-F27150 was amplified with primers ITS5 and P3 and directly sequenced (4). The resulting 554-bp sequence was deposited in GenBank (Accession No. KC414675). The amplified ITS sequence shared >99% similarity with the sequences of E. cruciferarum on several brassicaceous hosts (EU140958, FJ548627, and GU721075). Pathogenicity was confirmed through inoculation by gently dusting conidia onto leaves of five healthy potted garden cress plants. Five non-inoculated plants served as controls. Inoculated plants were isolated from non-inoculated plants in separate rooms in a greenhouse at 18 to 24°C. Inoculated plants developed signs and symptoms after 8 days, whereas the control plants remained symptomless. The fungus present on the inoculated plants was morphologically identical to that originally observed on diseased plants, fulfilling Koch's postulates. Previously, the disease was reported in several European countries and southeastern Asia (Lebanon, Israel, Iran, Iraq, India, and China) (3). To our knowledge, this is the first report of powdery mildew caused by E. cruciferarum on garden cress in Korea. Since garden cress production was only recently started on a commercial scale in Korea, powdery mildew infections pose a serious threat to the production of this herb, especially in organic farming where chemical control options are limited. 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) S. Choudhary et al. Indian J. Agric. Sci. 80:752, 2010. (3) D. F. Farr and A. Y. Rossman. Fungal Databases, Syst. Mycol. Microbiol. Lab., Online publication. ARS, USDA. Retrieved December 2, 2012. (4) S. Takamatsu et al. Mycol. Res. 113:117, 2009.

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