First Report of Powdery Mildew Caused by Erysiphe cruciferarum on Wasabi (Wasabia japonica) in Korea

California poppy is an annual species grown widely in the Pacific Northwest. Once established, populations are self-seeding and require little care. During an ongoing study of Erysiphales, a powdery mildew fungus was collected repeatedly on this species in Seattle, WA. The fungus was determined to be Erysiphe cruciferarum Opiz ex Junell, a species not reported previously on this host in North America. This report documents the occurrence of the disease and provides information on the morphology and identification of the causal agent. Accepted for publication 8 November 2006. Published 13 December 2006.

Download Full-text

First Report of Powdery Mildew Caused by Erysiphe cruciferarum on Brassica napus in China

Plant Disease ◽

10.1094/pdis-03-15-0351-pdn ◽

2015 ◽

Vol 99 (11) ◽

pp. 1651-1651 ◽

Cited By ~ 5

Author(s):

J. T. Alkooranee ◽

S. Liu ◽

T. R. Aledan ◽

Y. Yin ◽

M. Li

Keyword(s):

Brassica Napus ◽

Powdery Mildew ◽

First Report ◽

Erysiphe Cruciferarum

Download Full-text

First Report of Powdery Mildew Caused by Erysiphe cruciferarum on Camelina sativa in Montana

Plant Disease ◽

10.1094/pdis-10-21-2362-pdn ◽

2021 ◽

Author(s):

Benzhong Fu ◽

Qing Yan

Keyword(s):

United States ◽

Powdery Mildew ◽

The United States ◽

Camelina Sativa ◽

Its Sequences ◽

Flowering Plant ◽

Biofuel Crop ◽

First Report ◽

Erysiphe Cruciferarum ◽

Query Cover

Camelina sativa (L.) Crantz, also known as false flax, is an annual flowering plant in the family Brassicaceae and originated in Europe and Asia. In recent years, it is cultivated as an important biofuel crop in Europe, Canada, and the northwest of the United States. In June of 2021, severe powdery mildew was observed on C. sativa ‘Suneson’ plants under greenhouse conditions (temperature 18.3°C/22.2°C, night/day) in Bozeman, Montana (45°40'N, 111°2'W). The disease incidence was 80.67% (150 pots, one plant per pot). White ectophytic powdery mildew including mycelia and conidia were observed on the upper leaves, usually developed from bottom tissues to top parts, also present on stems and siliques. Mycelia on leaves were amphigenous and in patches, often spreading to become effused. These typical symptoms were similar to a previous report of powdery mildew on Broccoli raab (Koike and Saenz 1997). Appressoria are lobed, and foot cells are cylindrical with size 18 to 26 × 7 to 10 μm. Conidia are cylindrical and produced singly, with a size of 35 to 50 × 12 to 21 μm and a length : width ratio greater than two (Koike and Saenz 1997). No chasmothecia were observed under the greenhouse conditions. The symptoms and fungal microscopic characters are typical of Pseudoidium anamorph of Erysiphe (Braun 1995). The specific measurements and characteristics are consistent with previous records of Erysiphe cruciferarum Opiz ex L. Junell (Braun and Cook 2012; Vellios et al. 2017). To identify the pathogen, the partial internal transcribed spacer (ITS) region of rDNA of sample CPD-1 was amplified using primers ITS1 and ITS4 (White et al. 1990). The amplicons were sequenced, and the resulting 559-bp sequence was deposited in GenBank (CPD-1, Accession number: OK160719). A GenBank BLAST search of the ITS sequences showed an exact match (100% query cover, E-value 0, and 100% identity 559/559 bp) with those of E. cruciferarum on hosts Brassica sp. (KY660929.1), B. juncea from Vietnam (KM260718.1) and China (KT957424.1). A phylogenetic tree was generated with the CPD-1 ITS sequence with several of ITS sequences of close species with different hosts obtained from the GenBank. Isolate CPD-1 was grouped with pathogens from Brassica hosts rather than the holotype strain (KU672364.1) from papaveraceous hosts. To fulfill Koch's postulates, pathogenicity was confirmed through inoculation by dusting conidia onto leaves of seven healthy, potted, 14-day-old C. sativa seedlings (cv. Suneson). Seven non-inoculated plants served as a control treatment. The plants were incubated in a greenhouse with a temperature of 18°C (night) to 22°C (day). The inoculated plants developed similar symptoms after 7 days, whereas the control plants remained symptomless. The fungus on the inoculated plants was morphologically identical to that was originally observed on the diseased plants. Though many Brassica spp. have been known to be infected by E. cruciferarum throughout the world, powdery mildew of C. sativa cultivar Crantz in natural conditions by E. cruciferarum has been reported only in the province of Domokos in Central Greece (Vellios et al. 2017). To our knowledge, this is the first report of powdery mildew caused by E. cruciferarum on C. sativa in Montana. Though the powdery mildew on C. sativa was observed in the greenhouse conditions in this work, it poses a potential threat to the production of this biofuel crop in the northwest of the United States.

Download Full-text

First report of Erysiphe cruciferarum causing powdery mildew of Alliaria petiolata in Maryland

Plant Disease ◽

10.1094/pdis-09-21-2060-pdn ◽

2021 ◽

Author(s):

Michael Robert Fulcher ◽

Paul C Owen-Smith

Keyword(s):

Powdery Mildew ◽

Invasive Plant ◽

Local Population ◽

Alliaria Petiolata ◽

Specific Information ◽

Garlic Mustard ◽

Internal Transcribed Spacer Region ◽

First Report ◽

Erysiphe Cruciferarum ◽

Disease Free

Alliaria petiolata (Bieb.) Cavara & Grande (garlic mustard) is a biennial crucifer native to Europe and invasive in North America, where it outcompetes native plants in deciduous forests. In July 2021, powdery mildew was observed on A. petiolata in Frederick County, Maryland. Signs of the disease included white, tomentose mycelium producing abundant conidia (Fig S1). A majority of plants were affected, and severity ranged from the presence of small, discrete infections to complete colonization of leaves, stems, and ripening seed pods. Conidia from field collected leaves were transferred to disease-free A. petiolata for maintenance in a growth chamber at 20°C and 80% RH with a 12 hr photoperiod. Fungal morphology was recorded 30 days after this transfer. Appressoria were irregularly lobed, and conidiophores were straight and composed of 2-3 cells. Cylindrical to oblong conidia were produced singly in pseudochains of 2-6 (x̄ = 3), measured 39-64 by 18-29 (x̄ = 52 by 24) μm, had a length to width ratio greater than two, and germinated at the ends. Fibrosin bodies were absent from conidia, and chasmothecia were not observed in the field or on inoculated plant material. Based on anamorphic characteristics, the pathogen was placed in the genus Erysiphe (Boesewinkel 1980). Species level identity was determined using DNA sequences. Conidia and mycelia were scraped from leaves and used for genomic DNA extraction with the Quick-DNA Fungal/Bacterial Miniprep Kit (Zymo Research, Irvine, CA). A portion of the internal transcribed spacer region of rDNA was amplified using the primers ITS5/ITS4 (White et al. 1990). Purified amplicons (PCR & DNA Cleanup Kit, New England BioLabs Inc., Ipswich, MA) were sequenced at Eurofins Genomics (Louisville, KY). The resulting sequence was compared to those in NCBI GenBank using the blastn algorithm (Altschul et al. 1990). The newly generated sequence (GenBank: OK157430) was identical (599/599 bp) to samples of E. cruciferarum from the United Kingdom (GenBank: KY660931.1, KY660879.1, KY660752.1). Because E. cruciferarum sensu lato is heterogeneous (Pastirčáková et al. 2016), additional sequence comparisons were made to the E. cruciferarum sensu stricto holotype (589/599 bp, GenBank: KU672364) and a vouchered E. cruciferarum s. lat. (596/599 bp, GenBank: LC009943). This supports identification of the pathogen as E. cruciferarum s. lat. and suggests the taxonomy of isolates from A. petiolata should be reassessed following any revision to E. cruciferarum. A modified Koch’s postulates procedure was followed to confirm pathogenicity. Leaves colonized by E. cruciferarum were briefly pressed against the leaves of three disease-free plants grown from seed in a greenhouse. After 14 days, inoculated plants showed signs of powdery mildew similar to those observed in the field, and a control treatment using pathogen-free leaves resulted in no disease. This inoculation experiment was performed twice, and the identity of the pathogen was reconfirmed based on morphology. This is the first report of powdery mildew on A. petiolata in Maryland. Erysiphe cruciferarum s. lat. is widely distributed on other hosts and has been found on A. petiolata throughout Europe and in Ohio and Indiana (Farr and Rossman 2021; Blossey et al. 2001; Enright and Cipollini 2007; Ciola and Cipollini 2011). This pathogen has been proposed as a biological control agent (Cipollini and Enright 2009; Cipollini et al. 2020), and the presence of disease in Maryland suggests the local population of A. petiolata is susceptible to E. cruciferarum and the environment there is favorable to disease development. References: Altschul, S. F., et al. 1990. J. Mol. Biol. 215:403. Blossey, B., et al. 2001. Nat. Areas J. 21:357. Boesewinkel, H. J. 1980. Bot. Rev. 46:167. Ciola, V., and Cipollini, D. 2011. Am. Midl. Nat. 166:40-52. Cipollini, D., and Enright, S. M. 2009. Invasive Plant Sci. Manag. 2:253. Cipollini, D., et al. 2020. Biol. Invasions. 22:1657-1668. Enright, S. M., and Cipollini, D. 2007. Am. J. Bot. 94:1813. Farr, D. F., and Rossman, A. Y. 2021. Fungal Databases, Syst. Mycol. Microbial. Lab., ARS, USDA. https://nt.ars-grin.gov/fungaldatabases/ Pastirčáková, K., et al. 2016. Mycol. Prog. 15:36 White, T. J., et al. 1990. Page 315 in: PCR Protocols. A Guide to Methods and Applications, Academic Press, San Diego. Keywords: Alliaria petiolata, Erysiphe cruciferarum, garlic mustard, powdery mildew, invasive plant, biocontrol Funding and Disclaimer: The author(s) declare no conflict of interest. This work was supported by USDA-ARS Appropriated Project Number 8044-22000-047-000-D. Mention of trade names or commercial products in this report is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. USDA is an equal opportunity lender, provider, and employer.

Download Full-text

Management of powdery mildew, caused by Erysiphe cruciferarum, on wasabi (Wasabia japonica) plants in British Columbia

Canadian Journal of Plant Pathology ◽

10.1080/07060661.2020.1764109 ◽

2020 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

E.C. Betz ◽

Z.K. Punja

Keyword(s):

British Columbia ◽

Powdery Mildew ◽

Wasabia Japonica ◽

Erysiphe Cruciferarum

Download Full-text

First Report of Powdery Mildew Caused by Erysiphe cruciferarum on Arabidopsis thaliana in Korea

The Plant Pathology Journal ◽

10.5423/ppj.2009.25.1.086 ◽

2009 ◽

Vol 25 (1) ◽

pp. 86-90 ◽

Cited By ~ 4

Author(s):

Hyong-Woo Choi ◽

Young-Jun Choi ◽

Dae-Sung Kim ◽

In-Sun Hwang ◽

Du-Seok Choi ◽

...

Keyword(s):

Arabidopsis Thaliana ◽

Powdery Mildew ◽

First Report ◽

Erysiphe Cruciferarum

Download Full-text

First Report of Powdery Mildew Caused by Erysiphe cruciferarum on Indian Mustard (Brassica juncea) in Korea

Plant Disease ◽

10.1094/pdis-04-13-0378-pdn ◽

2013 ◽

Vol 97 (10) ◽

pp. 1383-1383 ◽

Cited By ~ 3

Author(s):

J. Y. Kim ◽

B. S. Kim ◽

S. E. Cho ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Brassica Juncea ◽

Former Soviet Union ◽

Indian Mustard ◽

Its Region ◽

Hyphal Growth ◽

Control Treatment ◽

Width Ratio ◽

First Report ◽

Erysiphe Cruciferarum

Indian mustard (Brassica juncea (L.) Czern.) belongs in the Brassicaceae and is widely cultivated in Korea for the edible leaves. In May 2011, Indian mustard plants of cv. Cheong-Kyeoja, growing in polyethylene-film-covered greenhouses in Hwaseong, Korea, were observed to be affected by a powdery mildew. Symptoms appeared as circular to irregular white colonies, which subsequently showed abundant hyphal growth on both leaf surfaces. Severely infected plants were unmarketable due to leaf discoloration, and most were not harvested. Voucher specimens have been deposited in the Korea University Herbarium (KUS). Appressoria on the mycelium were well developed, lobed, solitary, or in opposite pairs. Conidiophores were cylindrical, 70 to 115 × 8 to 10 μm, and composed of 3 to 4 cells. Foot-cells of conidiophores were straight to substraight, cylindrical, and relatively short (20 to 30 μm long). Singly-produced conidia were oblong to cylindrical or oval, 27.5 to 50 × 14 to 17.5 μm with a length/width ratio of 1.8 to 3.6, with angular/rectangular wrinkling of outer walls, and lacked distinct fibrosin bodies. Germ tubes were produced in 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 and characteristics were consistent with previous records of Erysiphe cruciferarum Opiz ex L. Junell (1). To confirm the identification, the complete internal transcribed spacer (ITS) region of rDNA of KUS-F24819 was amplified with primers ITS5 and P3 (4), and sequenced directly. The resulting 462-bp sequence was deposited in GenBank (Accession No. KC862331). A GenBank BLAST search of the ITS sequence showed 100% identity (462/462 bp) with those of isolates of E. cruciferarum from B. oleracea var. acephala, B. rapa, and Arabidopsis thaliana (GU721075, EU140958, and FJ548627, respectively). Pathogenicity was confirmed through inoculation by gently dusting conidia onto leaves of five healthy, potted Indian mustard plants of the cv. Cheong-Kyeoja. Five non-inoculated plants served as a control treatment. Inoculated plants were isolated from non-inoculated plants in separate rooms in a greenhouse at 18 to 24°C. Inoculated plants developed symptoms after 7 days, whereas the control plants remained symptomless. The fungus present on the inoculated plants was identical morphologically to that originally observed on the diseased plants, fulfilling Koch's postulates. There are records of E. cruciferarum infecting B. juncea in Europe (Finland, Romania, Sweden, Switzerland), the former Soviet Union, Australia, South Africa, and Asia (India, Japan, and China) (2,3). To our knowledge, this is the first report of powdery mildew caused by E. cruciferarum on B. juncea in Korea. Occurrence of powdery mildew is a threat to quality and marketability of this crop, 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. USDA ARS. Retrieved 20 March 2013. (3) P. Kaur et al. Plant Dis. 92:650, 2008. (4) S. Takamatsu et al. Mycol. Res. 113:117, 2009.

Download Full-text

First Report of Powdery Mildew Caused by Erysiphe cruciferarum on Oilseed Rape in Korea

Plant Disease ◽

10.1094/pdis-11-15-1388-pdn ◽

2016 ◽

Vol 100 (6) ◽

pp. 1245-1245

Author(s):

S. E. Cho ◽

J. H. Park ◽

Y. J. Choi ◽

I. Y. Choi ◽

H. D. Shin

Keyword(s):

Powdery Mildew ◽

Oilseed Rape ◽

First Report ◽

Erysiphe Cruciferarum

Download Full-text

First Report of Powdery Mildew, Caused by Erysiphe cruciferarum, on Broccoli Raab in California

Plant Disease ◽

10.1094/pdis.1997.81.9.1093c ◽

1997 ◽

Vol 81 (9) ◽

pp. 1093-1093 ◽

Cited By ~ 6

Author(s):

S. T. Koike ◽

G. S. Saenz

Keyword(s):

Powdery Mildew ◽

Disease Incidence ◽

Width Ratio ◽

First Report ◽

Erysiphe Cruciferarum ◽

Salinas Valley ◽

Inoculation Procedure ◽

Uninoculated Control ◽

Test Plants ◽

Commercial Field

Broccoli raab (Brassica rapa subsp. rapa), also known as rappini, is a leafy vegetable that is widely grown in Europe and has in recent years become an important crop in coastal California. During summer months in the Salinas Valley (Monterey County) in California, powdery mildew was observed on commercial field and greenhouse-grown plants. White ectophytic mycelial and conidial growth was present on leaves, causing chlorosis, and also developed on stems. Mycelia were amphigenous, in patches, often spreading to become effused. Appressoria were lobed and conidiophores were straight. Foot cells were cylindrical, measured 18 to 26 × 7 to 10 μm, and were followed by one to two cells of variable length. Conidia were produced singly, were cylindrical, and measured 35 to 50 × 12 to 21 μm with a length-to-width ratio greater than 2. No fibrosin bodies were observed in the conidia, and conidia germinated at the ends. Cleistothecia were not observed. The fungus was identified as Erysiphe cruciferarum Opiz ex Junell (1). Pathogenicity was demonstrated by gently pressing infected leaves having abundant sporulation onto leaves of potted broccoli raab (cv. Spring Raab), incubating the plants in a moist chamber for 48 h, and then maintaining plants in a greenhouse. After 10 to 13 days, powdery mildew colonies developed on the test plants. Uninoculated control plants did not develop powdery mildew. With the same inoculation procedure, potted broccoli (Brassica oleracea subsp. botrytis cv. Greenbelt) also became infected by the broccoli raab isolates. This is the first report characterizing this pathogen on broccoli raab in the state. Disease incidence and severity in field-planted crops were low, but greenhouse-grown plants became severely infected. Reference: (1) U. Braun. Beih. Nova Hedwigia 89:1, 1987.

Download Full-text

First Report of Powdery Mildew Caused by Erysiphe cruciferarum on Chinese Cabbage in China

Plant Disease ◽

10.1094/pdis-06-13-0648-pdn ◽

2014 ◽

Vol 98 (3) ◽

pp. 421-421 ◽

Cited By ~ 4

Author(s):

H. H. Zhao ◽

H. H. Xing ◽

C. Liang ◽

X. Y. Yang ◽

S. E. Cho ◽

...

Keyword(s):

Powdery Mildew ◽

Chinese Cabbage ◽

Control Treatment ◽

Width Ratio ◽

Pathogenicity Test ◽

Potential Threat ◽

Voucher Specimen ◽

First Report ◽

Powdery Mildews ◽

Erysiphe Cruciferarum

Chinese cabbage, Brassica rapa ssp. pekinensis (syn. Brassica pekinensis (Lour.) Rupr.), in the Brassicaceae, is an important vegetable grown on about 3 million ha in China. Since 2012, a powdery mildew has been found infecting Chinese cabbage plants (cv. Qingyanchunbai No. 1) after bolting for seed production from autumn through spring 2013 in a greenhouse in Qingdao, China. Symptoms first appeared as circular to irregular white patches on both sides of the leaves, and on stems and pods, often thinly covering the whole surface. A voucher specimen was deposited in the herbarium of Qingdao Agricultural University (Accession No. HMQAU12216). Hyphae were thin-walled, smooth, hyaline, and 4 to 6 μm wide. Appressoria on the mycelia were well developed, lobed, solitary, or in pairs. Conidiophores were erect, cylindrical, 45 to 110 μm long, and comprised 3 to 4 cells. Foot-cells of conidiophores were straight, cylindrical, 16 to 28 μm long, and 7.6 to 10 μm wide. Singly-produced conidia were oblong to cylindrical or somewhat ellipsoid-doliiform, 32 to 56 × 12 to 18 μm, with a length/width ratio of 1.8 to 3.8, with angular/rectangular wrinkling of the outer wall surface, and lacked distinct fibrosin bodies. Germ tubes were produced in the perihilar position of conidia. No chasmothecia were found. These structures are typical of the powdery mildew Pseudoidium anamorph of Erysiphe (2). The specific measurements and characteristics (especially short foot-cells of conidiophores) were consistent with previous records of Erysiphe cruciferarum Opiz ex L. Junell (2,3). To confirm the identification, the complete internal transcribed spacer (ITS) region of rDNA of isolate HMQAU12216 was amplified (4) and sequenced directly. The resulting 649-bp sequence was deposited in GenBank (Accession No. KC878683). A GenBank BLAST search of ITS sequences showed an exact match with those of E. cruciferarum on B. oleracea var. acephala (GU721075) and Oidium sp. on B. pekinensis (AB522714). A pathogenicity test was conducted by gently pressing a symptomatic leaf loaded with conidia onto a leaf of each five, healthy, potted, 40-day-old plants (cv. Qingyanchunbai No. 1). Five non-inoculated plants served as a control treatment. Inoculated plants were isolated from non-inoculated plants in separate rooms in a greenhouse at 20 ± 2°C. Inoculated plants developed signs and symptoms after 10 days, whereas the control plants remained symptomless. The fungus present on the inoculated plants was identical morphologically to that originally observed on diseased plants, thus fulfilling Koch's postulates. Though many Brassica spp. have been known to be infected with E. cruciferarum throughout the world, powdery mildew of Chinese cabbage caused by E. cruciferarum has been reported only in Finland, Germany, and Korea (1,3). To our knowledge, this is the first report of powdery mildew caused by E. cruciferarum on Chinese cabbage in China. Though occurrence of the powdery mildew on Chinese cabbage was noticed in an experimental breeding plot, this finding poses a potential threat to production of this vegetable in China. References: (1) U. Braun. The Powdery Mildews (Erysiphales) of Europe. Gustav Fischer Verlag, Jena, Germany, 1995. (2) U. Braun and R. T. A. Cook. Taxonomic Manual of the Erysiphales (Powdery Mildews), CBS Biodiversity Series No. 11. CBS, Utrecht, 2012. (3) H. J. Jee et al. Plant Pathol. 57:777, 2008. (4) S. Matsuda and S. Takamatsu. Mol. Phylogen. Evol. 27:314, 2003.

Download Full-text