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

Plant Disease ◽  
2011 ◽  
Vol 95 (10) ◽  
pp. 1317-1317 ◽  
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.

scholarly journals First Report of Powdery Mildew Caused by Golovinomyces biocellatus on Monarda didyma in Korea

Plant Disease ◽  
2011 ◽  
Vol 95 (12) ◽  
pp. 1590-1590
Author(s):  
K. S. Han ◽  
M. J. Park ◽  
S. E. Cho ◽  
H. D. Shin
Keyword(s):  
Powdery Mildew ◽  
Sequence Similarity ◽  
Morphological Characteristics ◽  
Signs And Symptoms ◽  
Width Ratio ◽  
Lateral Part ◽  
Rdna Sequences ◽  
Severe Infections ◽  
Length Width ◽  
Monarda Didyma

Bergamot (Monarda didyma L.), which is native to eastern North America, is an aromatic herb in the family Lamiaceae. It is widely planted in gardens and parks for ornamental purposes and also grown indoors as a fragrant houseplant in Korea. In October 2007, several dozen bergamots planted outdoors in Bonghwa, Korea were found to be heavily infected with a powdery mildew. Symptoms first appeared as thin, white colonies, which subsequently developed into abundant growth on both sides of the leaves. Severe infections often caused leaf distortions and premature senescence. The same symptoms have also been found in bergamot plots in Osan, Suwon, Incheon, and Seoul from 2007 to 2011. Voucher specimens were deposited at Korea University, Seoul, Korea. Hyphae were septate, branched, and 4 to 8 μm wide. Appressoria on the mycelium were nipple shaped. Conidiophores arose from the lateral part of the hyphae, measured 100 to 180 × 10 to 12 μm, were simple, and produced two to four immature conidia in chains, followed by two to three cells. Conidia were hyaline, ellipsoid to barrel shaped, measured 28 to 40 × 16 to 20 μm (length/width ratio = 1.4 to 2.2), lacked distinct fibrosin bodies, and produced germ tubes on the subterminal 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 Golovinomyces biocellatus (Ehrenb.) V.P. Heluta as described previously (1,4). The only other powdery mildew known on Monarda spp. is Neoerysiphe galeopsidis (1), which is clearly distinguished by its lobed hyphal appressoria and fine striations on conidial surfaces. To confirm the tentative identification based on morphological characteristics, internal transcribed spacer (ITS) rDNA sequences from two representative isolates (KUS-F23070 and F23117) were obtained using primers ITS5 and P3 as described by Takamatsu et al. (3). The resulting sequences of 523 bp were deposited in GenBank (Accession Nos. JN228358 and JN228359). A GenBank BLAST search produced an exact match for the sequences of G. biocellatus on several plants belonging to the Lamiaceae, with a 100% sequence similarity. Pathogenicity was confirmed through inoculation by gently pressing diseased leaves onto leaves of five healthy potted bergamot plants. Five noninoculated plants served as controls. Plants were maintained in a greenhouse at 25 ± 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. The powdery mildew infections of bergamot plants associated with G. biocellatus have been known in Europe (2) and Japan (4). The current work confirmed the occurrence of G. biocellatus infecting M. didyma in Korea. 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/ , July 12, 2011, (3) S. Takamatsu et al. Mycol. Res. 113:117, 2009. (4) S. Tanda. J. Agric. Sci. Tokyo Agric. Univ. 47:274, 1997.

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

Plant Disease ◽  
2014 ◽  
Vol 98 (7) ◽  
pp. 999-999 ◽  
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.

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

Plant Disease ◽  
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.

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

Plant Disease ◽  
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.

scholarly journals Occurrence of Powdery Mildew Caused by Blumeria graminis f. sp. poae on Poa pratensis in China

Plant Disease ◽  
2020 ◽  
Author(s):  
Mo Zhu ◽  
Jie Ji ◽  
Wenqi Shi ◽  
YongFang Li
Keyword(s):  
Powdery Mildew ◽  
Germ Tube ◽  
Poa Pratensis ◽  
Perennial Grass ◽  
Morphological Characteristics ◽  
Signs And Symptoms ◽  
Its Region ◽  
Width Ratio ◽  
Leaf Surfaces ◽  
Length Width

Poa pratensis, known as bluegrass, is a perennial grass and one of the best varieties with highly valued pasture and turf grass uses. It is widely grown on golf courses and used for lawns in squares and parks (Luo et al. 2020). During April and May 2020, powdery mildew-like signs and symptoms were observed on leaves of P. pratensis in Muye Park, Xinxiang city (35.3°N; 113.9°E), Henan Province, China. White or grayish powdery masses in spots- or coalesced lesions were abundant on the adaxial surfaces of leaves and covered up to 90 % of the leaf area. Some of the mildew-infested leaves appeared chlorotic or began senescence. Mildew-infested leaves were collected to microscopically observe the morphological characteristics of this pathogen. Conidiophores were composed of foot cells, followed by one or two cells, and conidia. The ellipsoid- shaped conidia (n = 50) were 25 - 36 × 10 - 15 μm (length × width), on average 30 × 13 μm, with a length/width ratio of 2.3. Foot-cells (n = 15) were 30 - 44 μm long and 7 - 15 μm wide. On leaf surfaces, germinated conidia produced a short primary germ tube and then a long secondary germ tube that finally differentiated into a hooked appressorium. Chasmothecia were not found. Based on these morphological characteristics, the pathogen was initially identified as B. graminis f. sp. poae, the known forma specialis (f. sp.) of B. graminis on P. pratensis (Braun and Cook 2012; Troch et al. 2014). Mycelia of the pathogen were scraped from infected leaves and total genomic DNA was isolated using the method described previously (Zhu et al. 2019). The rDNA internal transcribed spacer (ITS) region was amplified applying primer pairs ITS1/ITS4 (White et al. 1990). The amplicon was cloned and sequenced by Invitrogen (Shanghai, China). The obtained sequence for the pathogen was deposited into GenBank under Accession No. MT892956 and was 100 % identical (549/549 bp) to B. graminis on P. pratensis (AB273530) (Inuma et al. 2007). In addition, the phylogenetic analysis clearly showed that the identified fungus and B. graminis f. sp. poae were clustered in the same branch. To perform pathogenicity analysis, leaf surfaces of eight healthy plants were inoculated by dusting fungal conidia from diseased leaves. Eight non-inoculated plants served as a control. The non-inoculated and inoculated plants were separately maintained in two growth chambers (humidity, 60 %; light/dark, 16 h/8 h; temperature, 18 ℃). Twelve to fourteen days after inoculation, B. graminis signs were visible on inoculated leaves, while control plants remained healthy. The pathogenicity assays were repeated twice and showed same results. Therefore, based on the morphological characteristics and molecular analysis, the pathogen was identified and confirmed as B. graminis f. sp. poae. This pathogen has been reported on P. pratensis in Switzerland and Japan (Inuma et al. 2007). This is, to our best knowledge, the first disease note reporting B. graminis on P. pratensis in China. Because the hybridization of B. graminis formae speciales (ff. spp.). allow the pathogens to adapt to new hosts, P. pratensis may serve as a primary inoculum reservoir of B. graminis to threaten other species, including cereal crops (Klingeman et al. 2018; Menardo et al. 2016). In addition, powdery mildew may negatively affect the yield and quality of grasses. Our report expands the knowledge of B. graminis f. sp. poae and provides the fundamental information for future powdery mildew control.

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

Plant Disease ◽  
2012 ◽  
Vol 96 (9) ◽  
pp. 1376-1376 ◽  
Author(s):  
M. J. Park ◽  
S. E. Cho ◽  
M. Piątek ◽  
H. D. Shin
Keyword(s):  
Powdery Mildew ◽  
Sequence Similarity ◽  
Signs And Symptoms ◽  
Its Region ◽  
Botanical Garden ◽  
Central China ◽  
Perennial Herb ◽  
Width Ratio ◽  
First Report ◽  
Potted Plants

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.

scholarly journals First Report of Powdery Mildew Caused by Blumeria graminis f. sp. bromi on Bromus catharticus in China

Plant Disease ◽  
2020 ◽  
Author(s):  
Mo Zhu ◽  
Jie Ji ◽  
Xiao Duan ◽  
Wenqi Shi ◽  
YongFang Li
Keyword(s):  
Powdery Mildew ◽  
Sequence Data ◽  
Morphological Characteristics ◽  
Signs And Symptoms ◽  
The United States ◽  
Blumeria Graminis ◽  
Henan Province ◽  
Width Ratio ◽  
Causal Organism ◽  
First Report

Bromus catharticus, rescuegrass, is a brome grass that has been cultivated for herbage production, and been widely naturalized in many provinces of China, including Henan province. During April and May 2020, powdery mildew was found on leaves of Br. catharticus on the campus of Henan Normal University, Xinxiang city (35.3°N; 113.9°E), Henan Province, China. Abundant white or grayish irregular or coalesced circular powdery colonies were scattered on the adaxial surface of leaves and 70% of the leaf areas were affected. Some of the infected leaves either were chlorotic or senescent. About 60% of the observed plants showed powdery mildew symptoms. Conidiophores (n = 25) were 32 to 45 μm × 7 to 15 μm and composed of foot cells and conidia (mostly 6 conidia) in chains. Conidia (n = 50) were 25 to 35 μm × 10 to 15 μm, on average 30 × 13 μm, with a length/width ratio of 2.3. Chasmothecia were not found. Based on these morphologic characteristics, the pathogen was initially identified as Blumeria graminis f. sp. bromi (Braun and Cook 2012; Troch et al. 2014). B. graminis mycelia and conidia were collected, and total genomic DNA was extracted (Zhu et al. 2019). The rDNA internal transcribed spacer (ITS) region was amplified with primer pairs ITS1/ITS4. The amplicon was cloned and sequenced. The sequence (574 bp) was deposited into GenBank under Accession No. MT892940. BLASTn analysis revealed that MT892940 was 100% identical to B. graminis f. sp. bromi on Br. catharticus (AB000935, 550 of 550 nucleotides) (Takamatsu et al. 1998). Phylogenetic analysis of MT892940 and ITS of other B. graminis ff. spp. clearly indicated least two phylogenetically distinct clades of B. graminis f. sp. bromi and that MT892940 clustered with the Takamatsu vouchers. Leaf surfaces of five healthy plants were fixed at the base of a settling tower and then inoculated by blowing conidia from diseased leaves using pressurized air. Five non-inoculated plants served as controls. The inoculated and non-inoculated plants were maintained separately in two growth chambers (humidity, 60%; light/dark, 16 h/8 h; temperature, 18℃). Thirteen- to fifteen-days after inoculation, B. graminis signs and symptoms were visible on inoculated leaves, whereas control plants remained asymptomatic. The pathogenicity assays were repeated twice with the same results. The observed signs and symptoms were morphologically identical to those of the originally infected leaves. Accordingly, the causal organism of the powdery mildew was confirmed as B. graminis f. sp. bromi by morphological characteristics and ITS sequence data. B. graminis has been reported on Br. catharticus in the United States (Klingeman et al. 2018), Japan (Inuma et al. 2007) and Argentina (Delhey et al. 2003). To our best knowledge, this is the first report of B. graminis on Br. catharticus in China. Since hybridization of B. graminis ff. spp. is a mechanism of adaptation to new hosts, Br. catharticus may serve as a primary inoculum reservoir of B. graminis to infect other species (Menardo et al. 2016). This report provides fundamental information for the powdery mildew that can be used to develop control management of the disease in Br. catharticus herbage production.

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

Plant Disease ◽  
2012 ◽  
Vol 96 (7) ◽  
pp. 1072-1072 ◽  
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.

scholarly journals First Report of Powdery Mildew on Carrot Caused by Erysiphe heraclei in Michoacan, Mexico

Plant Disease ◽  
2010 ◽  
Vol 94 (4) ◽  
pp. 483-483 ◽  
Author(s):  
G. Rodríguez-Alvarado ◽  
R. Rodríguez-Fernández ◽  
A. Soto-Plancarte ◽  
S. P. Fernández-Pavía
Keyword(s):  
Powdery Mildew ◽  
Morphological Characteristics ◽  
Signs And Symptoms ◽  
Internal Transcribed Spacers ◽  
First Report ◽  
Daucus Carota L ◽  
5.8S Rdna ◽  
Rdna Sequences ◽  
Close Proximity ◽  
Pathogenicity Tests

Carrot (Daucus carota L. subsp. sativus (Hoffm.) Arcang.) is planted as a home-grown vegetable in the central region of Michoacan, Mexico. Powdery mildew was observed on carrot plants cv. Nantesa at several locations near Morelia, Michoacan during March 2009. Affected plants had abundant, white, superficial conidia and mycelium on leaves and stems. All plants at each of five locations surveyed had powdery mildew symptoms with percent foliage coverage ranging from 50 to 80%. Mycelial growth was amphigenous, mainly on the upper leaf surface, covering the whole leaf and with irregular patches on inflorescences and stems. Hyphae were ectophytic with lobed appressoria. Conidiophores presented foot cells 22.5 to 35 (30) × 5.75 to 7 (6.3) μm followed by two cells, one shorter and one longer than the foot cell. Conidia were produced singly, most subcylindric to cylindric, lacked fibrosin bodies, and measured 31.2 to 42 (36.2) × 8.7 to 11.2 (10.5) μm. The teleomorph was not observed. Genomic DNA was extracted from infected leaves; sequences of the internal transcribed spacers (ITS) inclusive of 5.8S rDNA were amplified using previously described primers specific for Erysiphales (3). The ITS sequences shared 100% homology to Erysiphe heraclei specimen VPRI41227 from carrot in Australia (GenBank Accession No. EU371725). On the basis of the morphological characteristics observed and the ITS rDNA sequences, the pathogen was identified as E. heraclei DC. The ITS sequence was deposited in NCBI as Accession No. GU252368. Pathogenicity tests were conducted twice on a total of 10 healthy 8-week-old carrot plants cv. Nantesa. Infected plants were placed in close proximity to healthy plants and maintained in a greenhouse at 27 ± 5°C. Initial signs and symptoms were observed 3 weeks after inoculation and appeared as small, white colonies, which later coalesced and covered most of the foliage. Microscopic examination of the conidia and mycelial morphology matched the originally described pathogen, E. heraclei. Powdery mildew caused by this pathogen has been extensively reported on diverse species and genera of the Apiaceae in Europe and remains one of the most important diseases of carrot (2). The appearance of E. heraclei in diverse regions on a variety of umbelliferous crops indicates that formae speciales have spread, infecting different and specific hosts (1–3). Recently, E. heraclei has been reported on parsley in Puebla, Mexico (4). To our knowledge, this is the first report of E. heraclei causing powdery mildew on carrot in Michoacan, Mexico. This pathogen should be considered as a threat to commercial carrot crops in Mexico. Other crops in the Apiaceae may not be at risk in this area if this powdery mildew is specific for carrots. References: (1) B. J. Aegerter. Page 22 in: Compendium of Umbelliferous Crop Diseases. The American Phytopathological Society, St. Paul, MN, 2002. (2) U. Braun. The Powdery Mildew (Erysiphales) of Europe. Gustav Fischer-Verlag. Jena, Germany, 1995. (3) J. H. Cunnington et al. Australas. Plant Pathol. 32:421, 2003. (4) M. J. Yáñez-Morales et al. Schlechtendalia 19:47, 2009.

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

Plant Disease ◽  
2013 ◽  
Vol 97 (11) ◽  
pp. 1514-1514 ◽  
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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