First Report of Powdery Mildew Caused by Phyllactinia actinidiae on Hardy Kiwi in Korea

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 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 Report of Powdery Mildew Caused by Podosphaera xanthii on Papaya in Korea

Plant Disease ◽

10.1094/pdis-06-13-0581-pdn ◽

2013 ◽

Vol 97 (11) ◽

pp. 1514-1514 ◽

Cited By ~ 2

Author(s):

J. H. Joa ◽

B. N. Chung ◽

K. S. Han ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Agricultural Research ◽

Morphological Characteristics ◽

Its Region ◽

Width Ratio ◽

Korean Isolate ◽

Podosphaera Xanthii ◽

First Report ◽

Powdery Mildews ◽

Basal Septum

In March 2013, papaya (Carica papaya L. cv. Sunrise) plants growing in polyethylene-film-covered greenhouses in Agricultural Research Center for Climate Change located in Jeju City, Korea, were observed severely affected by a powdery mildew. Symptoms appeared as circular to irregular white patches on both sides of the leaves. As the disease progressed, the plants were covered with dense masses of the spores, eventually causing senescence and withering of leaves. Voucher specimens were deposited in the Korea University Herbarium (KUS). Hyphae were flexuous to straight, branched, septate, and 5 to 8 μm wide. Conidiophores were 110 to 250 × 10 to 12.5 μm and produced 2 to 5 immature conidia in chains with a crenate outline followed by 2 to 3 cells. Foot-cells of conidiophores were straight, cylindric, slightly constricted at the basal septum, and 55 to 110 μm long. Conidia were hyaline, ellipsoid-ovoid, measured 22 to 38 × 18 to 21 μm with a length/width ratio of 1.2 to 1.8, and had distinct fibrosin bodies. Chasmothecia were scattered or partly clustered, dark brown, spherical, 80 to 100 μm in diameter, and each contained a single ascus. Appendages were mycelioid, 1- to 5-septate, brown at the base and becoming paler. Asci were sessile, 72 to 87 × 52 to 68 μm, had a terminal oculus of 17 to 23 μm wide, and contained 8 ascospores, each 17 to 23 × 12.5 to 15 μm. The morphological characteristics and measurements were consistent with those of Podosphaera xanthii (Castagne) U. Braun & Shishkoff (1). To confirm the identification, the complete internal transcribed spacer (ITS) region of rDNA of KUS-F27269 was amplified with the primers ITS5/P3 and sequenced (3). The resulting 443 bp sequence was deposited in GenBank (Accession No. KF111806). The Korean isolate showed >99% similarity with those of many P. xanthii isolates including an isolate on papaya from Taiwan (GU358450). Pathogenicity was confirmed through inoculation tests by gently pressing a diseased leaf onto young leaves of three asymptomatic, potted seedlings (cv. Sunrise). Three non-inoculated seedlings were used as control. Inoculated plants were isolated from non-inoculated plants in separate rooms in a greenhouse at 26 to 30°C. Inoculated leaves developed symptoms after 7 days, whereas the control plants remained symptomless. The fungus present on the inoculated leaves was identical morphologically to that observed on the original diseased leaves, fulfilling Koch's postulates. Powdery mildews of papaya caused by Podosphaera species including P. caricae-papayae have been reported in North America, South America, Hawaii, Africa, Ukraine, Australia, New Zealand, the Cook Islands, India, Thailand, Taiwan, and Japan (2,4). P. caricae-papayae is currently reduced to synonymy with P. xanthii (1). To our knowledge, this is the first report of powdery mildew caused by P. xanthii on papaya in Korea. Though papaya is a minor crop in Korea, producing about 300 M/T annually in greenhouses, powdery mildew disease is a threat to safe production of the fruits. 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 April 9, 2013. (3) S. Takamatsu et al. Mycol. Res. 113:117, 2009. (4) J. G. Tsay et al. Plant Dis. 95:1188, 2011.

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First Report of Powdery Mildew Caused by Golovinomyces cichoracearum on Zinnia elegans in Turkey

Plant Disease ◽

10.1094/pdis-06-11-0519 ◽

2011 ◽

Vol 95 (10) ◽

pp. 1317-1317 ◽

Cited By ~ 1

Author(s):

S. Soylu ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Molecular Analysis ◽

Sequence Similarity ◽

Morphological Characteristics ◽

Signs And Symptoms ◽

Current Data ◽

Zinnia Elegans ◽

Width Ratio ◽

Rdna Sequences ◽

Powdery Mildews

Powdery mildews are one of the most common diseases of plants growing in many nurseries, city parks, and home gardens in Turkey. Common zinnia (Zinnia elegans Jacq.) is widely cultivated in Turkey for ornamental purposes. In September 2010, zinnia plants grown in Hatay, Turkey were found to be heavily infected with a powdery mildew. Pathogen mycelia and sporulation were observed as circular to irregular, white patches on both sides of the leaves and on stems and flower petals. As the disease progressed, infected leaves turned yellow and died. Hyphae were straight to wavy and 4 to 7 μm wide. Conidiophores arose from the upper part of the hyphae, measured 120 to 190 × 10 to 13 μm, were simple, and produced two to six immature conidia in chains with a sinuate edge, followed by two to three straight cells. Conidia were hyaline, ellipsoid to barrel-shaped, measured 25 to 42 × 14 to 22 μm (length/width ratio = 1.3 to 2.5), lacked distinct fibrosin bodies, and produced germ tubes on the perihilar position, with reticulate wrinkling of the outer walls. No chasmothecia were observed. The structures described above were typical of the Oidium subgenus Reticuloidium, anamorph of the genus Golovinomyces, and the fungus measurements were compatible with those of G. cichoracearum (DC.) V.P. Heluta described previously (1,3). To confirm the tentative identification based on morphological characteristics, molecular analysis of internal transcribed spacer (ITS) rDNA sequences from a representative material (MKU-ZK311077, duplicate KUS-F25655) was conducted. The complete ITS regions of rDNA were amplified using primers ITS5 and P3 as described by S. Takamatsu (4) and sequenced. The resulting sequence of 508 bp from MKU-ZK311077 was deposited in GenBank (Accession No. JN051414). A GenBank BLAST search using the current data revealed an exact match for several sequences of G. cichoracearum, including Australian and Korean powdery mildews on zinnia plants, with a 100% sequence similarity. Pathogenicity was confirmed through inoculation by gently pressing diseased leaves onto leaves of three healthy, potted zinnia plants. Three noninoculated plants served as controls. Plants were maintained in a greenhouse at 25°C. Inoculated plants developed signs and symptoms after 10 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 Z. elegans associated with G. cichoracearum are nearly circumglobal, including Europe, North America, South America, Africa, Oceania, and Western Asian localities like India, Nepal, Jordan, and Israel (1,2). The current work confirmed the occurrence of G. cichoracearum infecting Z. elegans in Turkey using detailed morphological and molecular analysis. 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/ , May 24, 2011. (3) M. J. Park et al. Plant Pathol. J. 27:85, 2011. (4) S. Takamatsu et al. Mycol. Res. 113:117, 2009.

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Golovinomyces powdery mildews on Asteraceae in the Czech Republic

Plant Protection Science ◽

10.17221/129/2019-pps ◽

2020 ◽

Vol 56 (No. 3) ◽

pp. 163-179

Author(s):

Barbora Mieslerová ◽

Miloslav Kitner ◽

Veronika Petřeková ◽

Jitka Dvořáková ◽

Michaela Sedlářová ◽

...

Keyword(s):

Czech Republic ◽

Powdery Mildew ◽

Host Specificity ◽

Host Species ◽

Morphological Characteristics ◽

Fungal Species ◽

Great Variability ◽

The Czech Republic ◽

Powdery Mildews ◽

Asteraceae Family

Powdery mildews on the Asteraceae family were surveyed during 2007–2015 in the Czech Republic with the aim to increase our knowledge about occurrence, morphological characteristics and host specificity of powdery mildews on this family. In total, 32 host species with symptoms of powdery mildew were collected, and the fungal species were identified based on microscopic observations. These showed great variability in their morphological characteristics. Our study confirmed the high host specificity of powdery mildew species to their original hosts. A deeper knowledge of the taxonomy of the Asteraceae has brought substantial changes in the delimitation of powdery mildew species. In particular, delimitation of the three varieties of Golovinomyces asterum was studied and discussed.

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First Report of Powdery Mildew of Greenhouse Pepper Caused by Leveillula taurica in Canada

Plant Disease ◽

10.1094/pdis.1999.83.8.781a ◽

1999 ◽

Vol 83 (8) ◽

pp. 781-781 ◽

Cited By ~ 5

Author(s):

R. F. Cerkauskas ◽

J. Brown ◽

G. Ferguson ◽

S. Khosla

Keyword(s):

Powdery Mildew ◽

Leaf Surface ◽

Morphological Characteristics ◽

Chili Pepper ◽

Width Ratio ◽

Old Field ◽

First Report ◽

Leveillula Taurica ◽

Plastic Bags ◽

Abaxial Leaf Surface

In 1999, powdery mildew on cvs. Oberon and Triple 4 of greenhouse pepper (Capsicum annum L.) and cv. FireFlame of chili pepper was reported simultaneously in two commercial greenhouses at two separate locations, Leamington and Vineland, geographically separated by 290 km, in southern Ontario. Losses of 10 to 15% each in the 2 and 3.1 ha greenhouse pepper operations were noted. The greenhouse pepper industry in Canada consists of 89.4 ha with sales of $43.6 million (Canadian). Lesions appeared as a white, powdery coating on the abaxial leaf surface only, generally on the lower foliage of pepper plants, while diffuse chlorotic spots were present at corresponding locations on the adaxial surface. In chili pepper, this chlorosis was restricted to interveinal tissue, causing the leaves to have a somewhat netted appearance. In some cases, pale yellow spots appeared on the adaxial portion of the affected foliage during later stages of disease development. No cleistothecia were observed. Pyriform and cylindrical, hyaline, single-celled conidia were present in equal numbers. Both conidia had a network of crests and granules containing tiny, thornlike projections on the surface. These projections were also evident on the lower half of conidiophores. Pyriform conidia ranged in length from 61.6 to 84.0 μm (mean = 70.8, SE = 0.7) and in width from 14.0 to 25.8 μm (mean = 21.1, SE = 0.4, n = 50), with a mean length to width ratio of 3.4. Cylindrical conidia ranged in length from 54.9 to 80.1 μm (mean = 66.3, SE = 0.9) and in width from 15.7 to 24.1 μm (mean = 18.6, SE = 0.3, n = 50), with a mean length to width ratio of 3.1. Short conidial chains borne on conidiophores consisted of a pyriform conidium first followed by cylindrical conidium. Stomatal penetration and extensive endophytic mycelial growth in the mesophyll layer were evident in foliar tissue cleared with glacial acetic acid:EtOH (1:2) and stained with lactophenol cotton blue. To confirm pathogenicity, conidia from infected pepper leaves were dusted onto the water-misted abaxial leaf surface of 41-day-old greenhouse pepper cvs. Cubico and Edison, and onto the similarly treated adaxial leaf surface of 58-day-old field pepper cv. Renegade. Plants were enclosed in plastic bags for 24 h on a bench. Control plants were treated identically but not inoculated. Inoculated plants developed foliar powdery mildew symptoms, including sporulation similar to that of naturally infected plants. Occurrence of the fungus on the abaxial surface of pepper foliage, presence of endophytic mycelium, and the morphological characteristics of the imperfect state confirm the identity of the fungus. This is the first report of Leveillula taurica (Lév.) G. Arnaud on pepper in Canada. Reference: J. Palti. Bot. Rev. 54:423, 1988.

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First Report of Powdery Mildew of Greenhouse Pepper Caused by Leveillula taurica in British Columbia, Canada

Plant Disease ◽

10.1094/pdis.2003.87.9.1151c ◽

2003 ◽

Vol 87 (9) ◽

pp. 1151-1151 ◽

Cited By ~ 10

Author(s):

R. F. Cerkauskas ◽

A. Buonassisi

Keyword(s):

British Columbia ◽

Powdery Mildew ◽

Morphological Characteristics ◽

Width Ratio ◽

Abaxial Surface ◽

First Report ◽

Leveillula Taurica ◽

Abaxial Leaf Surface ◽

Cotton Blue ◽

Pepper Leaves

In 2003, powdery mildew of greenhouse pepper (Capsicum annuum L.) was reported simultaneously in two commercial greenhouses at two separate locations near Langley in southern British Columbia. Trace amounts of mildew on the foliage of cv. Zamboni in one operation, and 10 to 80% of the foliage of cv. Triple Four was affected in an organic operation, with losses in fruit yield of 2 to 4 kg/m2, were noted. The greenhouse pepper industry in British Columbia in 2001 comprised 76 ha with sales of $41.3 million (Canadian). Affected areas appeared as a white, powdery coating on the abaxial leaf surface of older foliage while diffuse chlorotic spots were present at corresponding locations on the adaxial surface. In some cases, pale yellow spots appeared on the adaxial portion of the affected foliage during later stages of disease development (2). Hyaline, single-celled pyriform and cylindrical conidia were present in 40:60 proportion, respectively. Both conidia had a network of crests and granules sometimes with tiny thorn-like projections on the surface. These projections were evident also on the lower half of conidiophores. Pyriform conidia ranged in length from 53.8 to 79.5 μm (mean = 68.0, SE = 0.8), and in width from 12.9 to 28.0 μm (mean = 20.1, SE = 0.6, n = 50) with a mean length to width ratio of 3.5. Cylindrical conidia had a length from 48.2 to 84.0 μm (mean = 66.0, SE = 0.9), and in width from 13.4 to 25.2 μm (mean = 18.6, SE = 0.4, n = 50) with a mean length to width ratio of 3.6. Short conidial chains borne on conidiophores consisted of a basal pyriform conidium followed by cylindrical conidium. No cleistothecia were observed. Stomatal penetration and extensive endophytic mycelial growth in the mesophyll layer were evident in foliar tissue cleared with glacial acetic acid/EtOH (1:2) and stained with lactophenol cotton blue. To confirm pathogenicity, a suspension of 2 × 104 conidia/ml from infected pepper leaves was applied onto the abaxial and adaxial leaf surfaces of 60-, 42-, and 28-day-old greenhouse pepper cv. Cubico, tomato cv. Trust, and cucumber cv. Corona, respectively. Plants were maintained in a growth chamber at 25/21°C day/night temperature and 80% relative humidity. Control plants in the same chamber were treated identically but not inoculated. After 21 days, inoculated pepper plants developed foliar powdery mildew symptoms on the abaxial surface, including sporulation similar to that of naturally infected plants. Occurrence of the fungus on the abaxial surface of pepper foliage, presence of endophytic mycelium, and the morphological characteristics of the imperfect state confirm the identity of the fungus (2). To our knowledge, this is the first report of Leveillula taurica (Lév.) G. Arnaud on pepper in British Columbia. The disease was first reported in Ontario, Canada in 1999 (1). References: (1) R. Cerkauskas et al. Plant Dis. 83:781,1999. (2) J. Palti. Bot. Rev. 54:423, 1988.

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First Report of Powdery Mildew Caused by Erysiphe macleayae on Torenia fournieri in China

Plant Disease ◽

10.1094/pdis-03-14-0294-pdn ◽

2014 ◽

Vol 98 (9) ◽

pp. 1277-1277 ◽

Cited By ~ 1

Author(s):

X.-Y. Men ◽

S.-Y. Liu ◽

W.-T. Jiang ◽

Y. Li

Keyword(s):

Powdery Mildew ◽

Morphological Characteristics ◽

Its Region ◽

Chelidonium Majus ◽

Torenia Fournieri ◽

Chinese Medicinal Herb ◽

First Report ◽

Advanced Stages ◽

Voucher Specimens ◽

Germ Tubes

Torenia fournieri (Linderniaceae) is a common ornamental plant in China. It is also an important Chinese medicinal herb for its heart clearing and toxin removal properties. In October 2013, severe powdery mildew infections were observed on T. fournieri in Baihuayuan Garden (125.35°E, 43.88°N), China. Voucher specimens were deposited in the Herbarium of Mycology of Jilin Agricultural University under the accession number HMJAU02176. Whitish colonies covered the surface of leaves, petioles, sepals, and stems. The infected leaves became yellow and necrotic by advanced stages of the infection. Chasmothecia with a diameter between 63.5 and 95 μm were present singly or in groups, and bore dark brown mycelioid. The appendages were 0.5 to 4 times as long as the chasmothecial diameter, brown at the base and paler toward the apex. Asci were 2 to 6 per chasmothecium, short-stalked or sessile, 50 to 62 × 30 to 50.5 μm, and 2- to 4-spored. Ascospores were pale brown, oval to ellipsoid, 27 to 43 × 13 to 17 μm. Hyphae were flexuous to straight, branched, and septate. Appressoria were well-developed, lobed, and solitary or in opposite pairs. Conidiophores were unbranched, cylindrical, and 94 to 185 × 9 to 15 μm. Foot-cells were straight, cylindrical, 19 to 40 μm long, and followed by 1 to 3 cells shorter or nearly equal to the foot-cell. Conidia were singly produced, cylindrical or oval, 34 to 44 × 16 to 20 μm, and without distinct fibrosin bodies. Lobed germ tubes were produced at the tip of conidia. The morphological characteristics of sexual and asexual structures were consistent with Erysiphe macleayae (1,2). To confirm the identification, the complete internal transcribed spacer (ITS) region of rDNA of the pathogen was amplified with the primers ITS1/ITS4 and sequenced (3). The resulting 574-bp sequence (KJ600796) showed 100% similarity with E. macleayae (KF856294) and Oidium sp. isolated from Chelidonium majus (HQ286645 to 46) and one base different from M. microcarpa (JQ681217). Koch's postulate was completed by gently pressing a diseased leaf onto three young excised leaves of asymptomatic seedlings. Three non-inoculated leaves were used as controls. Inoculated leaves were incubated in separate petri dishes in a greenhouse at 20 to 25°C. Symptoms developed 5 days after inoculation, whereas the control leaves remained symptomless (voucher specimens HMJAU02176I). The morphology of the fungus on the inoculated leaves was identical to that observed on the originally diseased leaves. Powdery mildew on T. fournieri has only been reported as Golovinomyces sp. in Hungary (4). To our knowledge, this is the first report of powdery mildew caused by E. macleayae on T. fournieri worldwide. Infection of Torenia by E. macleayae, a common powdery mildew on various hosts of the Papaveraceae, is very unusual and unexpected. It demonstrates a wider host range of this species beyond the limits of the Papaveraceae. References: (1) U. Braun and R. T. A. Cook. Taxonomic manual of the Erysiphales (Powdery Mildews), CBS Biodiversity Series 11. CBS, Utrecht, the Netherlands, 2012. (2) M. J. Park et al. Plant Dis. 96:1376, 2012. (3) S. Takamatsu et al. Mycol. Res. 113:117, 2009. (4) P. Vági et al. Eur. J. Plant Pathol. 117:89, 2007.

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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 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 Golovinomyces asterum var. solidaginis on Invasive Weed Solidago gigantea in Korea

Plant Disease ◽

10.1094/pdis-02-13-0154-pdn ◽

2013 ◽

Vol 97 (8) ◽

pp. 1120-1120 ◽

Cited By ~ 1

Author(s):

S. E. Cho ◽

J. H. Park ◽

S. H. Hong ◽

H. D. Shin

Keyword(s):

North America ◽

Powdery Mildew ◽

Morphological Characteristics ◽

Width Ratio ◽

Limiting Factor ◽

Indigenous Plants ◽

Invasive Weed ◽

First Report ◽

Solidago Gigantea ◽

Powdery Mildews

Solidago gigantea Aiton (syn. S. serotina Aiton), known as giant goldenrod, is native to North America and has been invasive in Europe and Asia. In Korea, this plant was accidentally introduced around the 1960s and has become widely naturalized by replacing indigenous plants and disrupting the native ecosystem (3). In October 2012, hundreds of giant goldenrod plants growing wild in riverine areas and roadsides were found affected by a powdery mildew in Busan, Korea. Voucher specimens were deposited in the Korea University Herbarium (KUS). Symptoms first appeared as circular to irregular white patches, which subsequently showed abundant hyphal growth on both sides of the leaves. Appressoria on the mycelium were nipple-shaped to moderately lobed. Conidiophores measured 120 to 240 × 10 to 12.5 μm, were arising laterally from hyphal mother cells, and produced 2 to 6 immature conidia in chains with a sinuate outline, followed by 2 to 3 cells. Foot-cells in conidiophores were 42 to 70 μm long and characterized by a distinctly curved base. Conidia were hyaline, ellipsoid to ovate, measured 28 to 42 × 17 to 24 μm (length/width ratio = 1.4 to 2.1), contained small oil drops, lacked distinct fibrosin bodies, and produced germ tubes on the subterminal position. No chasmothecia were observed. The morphological characteristics described above were typical of the Euoidium type anamorph of the genus Golovinomyces, and the fungus measurements and structures were consistent with those of G. asterum var. solidaginis U. Braun (1). To confirm the identity of the causal fungus, the complete ITS region of rDNA from isolate KUS-F27219 was amplified with primers ITS5 and P3 (4) and sequenced. The resulting 508-bp sequence was deposited in GenBank (Accession No. KC513763). A GenBank BLAST search of this sequence revealed >99% similarity with the ITS sequences of G. cichoracearum from Australia (GQ183940 ex Solidago sp.) and Japan (AB077625 ex S. altissima L. and AB077627 ex S. virgaurea subsp. asiatica Kitam. ex Hara). The G. cichoracearum isolates on Solidago spp. listed above are now placed in G. asterum var. solidaginis (1). Pathogenicity was confirmed through inoculation by gently pressing diseased leaves onto leaves of five healthy potted giant goldenrods. Five non-inoculated plants served as controls. Plants were maintained in a greenhouse at 24 to 30°C. Inoculated plants developed signs and symptoms after 7 days, whereas the control plants remained symptomless. The fungus present on inoculated plants was morphologically identical to that originally observed, fulfilling Koch's postulates. Association of S. gigantea with Golovinomyces powdery mildews has been known in North America, South America, Europe, New Zealand, Central Asia (Iran, Kazakhstan, and Kyrgyzstan), and Japan (2). To our knowledge, this is the first report of powdery mildew caused by G. asterum var. solidaginis on S. gigantea in Korea. Our field observations suggest that the powdery mildew could be a limiting factor to suppress the expansion of this invasive weed 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 January 22, 2013. (3) S. M. Oh et al. Kor. J. Weed Sci. 22:280, 2002. (4) S. Takamatsu et al. Mycol. Res. 113:117, 2009.

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