First Report of Powdery Mildew of Canadian Fleabane Caused by <i>Podosphaera erigerontis-canadensis</i> in China

HomePlant DiseaseVol. 103, No. 12First Report of Powdery Mildew of Canadian Fleabane Caused by Podosphaera erigerontis-canadensis in China PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Powdery Mildew of Canadian Fleabane Caused by Podosphaera erigerontis-canadensis in ChinaHua Guo, Han-Cheng Wang, De-Lun Li, Xue Chen, Wei Ding, and Zhong LiHua Guohttp://orcid.org/0000-0002-1027-8319College of Plant Protection, Southwest University, Chongqing 400715, P.R. ChinaGuizhou Center for Disease Control and Prevention, Guiyang 550004, P.R. China, Han-Cheng WangCollege of Plant Protection, Southwest University, Chongqing 400715, P.R. ChinaGuizhou Academy of Tobacco Science, Guiyang 550081, P.R. China, De-Lun LiBijie Tobacco Company, Bijie 551700, P.R. China, Xue ChenBijie Tobacco Company, Bijie 551700, P.R. China, Wei Ding†Corresponding authors: W. Ding; E-mail Address: dwing818@163.com and Z. Li; E-mail Address: zhongzhongligzu@163.comhttp://orcid.org/0000-0001-8536-5233College of Plant Protection, Southwest University, Chongqing 400715, P.R. China, and Zhong Li†Corresponding authors: W. Ding; E-mail Address: dwing818@163.com and Z. Li; E-mail Address: zhongzhongligzu@163.comCollege of Agriculture, Guizhou University, Guiyang 550025, P.R. ChinaAffiliationsAuthors and Affiliations Hua Guo1 2 Han-Cheng Wang1 3 De-Lun Li4 Xue Chen4 Wei Ding1 † Zhong Li5 † 1College of Plant Protection, Southwest University, Chongqing 400715, P.R. China 2Guizhou Center for Disease Control and Prevention, Guiyang 550004, P.R. China 3Guizhou Academy of Tobacco Science, Guiyang 550081, P.R. China 4Bijie Tobacco Company, Bijie 551700, P.R. China 5College of Agriculture, Guizhou University, Guiyang 550025, P.R. China Published Online:26 Sep 2019https://doi.org/10.1094/PDIS-04-19-0812-PDNAboutSections ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Erigeron canadensis L. is an annual herbaceous plant widely grown in China. It belongs to the Asteraceae family and is used as a feed plant for the farmer or as component for many traditional Chinese medicines. In August 2018 in Zhijing County (26.36°N, 105.48°E) of China, severe infection of E. canadensis by a powdery mildew was observed in a 4-ha field where Canadian fleabane was being produced. Approximately 50% of the plants were symptomatic, and 35% of the leaves were infected. Powdery mildew colonies were circular to irregular in shape and formed white patches on the adaxial surface of the leaves. Irregular spots and/or necrotic symptoms on the surface of leaves were also observed in autumn and winter. Premature senescence of the leaves occurred when severe infection happened. A voucher specimen (PC-1) was selected for identification. The pathogen was examined in a microscopy for morphological characters. Conidiophores of the pathogen were composed of a subcylindrical foot cell, which was followed by one to three short cells, and were erect, straight, and 80 to 220 × 10 to 15 μm (n = 80). Conidia were limoniform to doliiform, and measured 27 to 40 × 15 to 20 μm. These morphological characteristics were identical with those of the anamorph of Podosphaera erigerontis-canadensis (Lév.) U. Braun & T.Z. Liu (Braun and Cook 2012). Species verification was completed by PCR amplification and BLAST analyses of the partial internal transcribed spacer (ITS) ribosomal DNA (rDNA) and the 28S ribosomal RNA (rRNA) region (GenBank accession nos. MK787268.1 and MK795205.1, respectively) (Yang et al. 2018). Both sequences showed 100% identity with sequences of P. erigerontis-canadensis: KU563734.1 for ITS rDNA and KX610821.1 for 28S rRNA. Pathogenicity of the fungus was verified in the greenhouse according to Koch's postulates. Healthy E. canadensis plants at 2-month-old stage were selected for the test. Conidia from an infected plant were gently dusted onto six plants. Six noninoculated plants were also included as controls. For symptom development after the inoculation, plants were kept in a greenhouse at 25°C, >75% relative humidity, 100 lux, and 16 h light/day. Inoculated plants developed powdery mildew symptoms and signs after 10 days similar to those on symptomatic plants in the field, whereas control plants remained asymptomatic. The experiments were conducted twice. Previously in China and in Switzerland, powdery mildew on E. canadensis has been reported to be caused by Podosphaera fusca (Bolay 2005; Park et al. 2010). Additionally, P. erigerontis-canadensis was also found to cause powdery mildew on Conyza bonariensis in Korea (Hong et al. 2017) and on Taraxacum officinale in the United States (Yang et al. 2018). However, this is the first report of P. erigerontis-canadensis causing powdery mildew on E. canadensis in China. Because this disease can spread rapidly through aerial abundant dissemination of conidia, P. erigerontis-canadensis has the potential to cause considerable economic loss to farmers. Disease management of powdery mildew on E. canadensis needs to be developed to reduce losses in the future.The author(s) declare no conflict of interest.References:Bolay, A., 2005. Cryptog. Helv. 20:1. Google ScholarBraun, U., and Cook, R. T. A. 2012. Page 707 in: Taxonomic Manual of the Erysiphales (Powdery Mildews). CBS-KNAW Fungal Biodiversity Centre, Utrecht, the Netherlands. Google ScholarHong, S. H., et al. 2017. Plant Dis. 101:1674. Link, Google ScholarPark, M.-J., et al. 2010. Fung. Biol. 114:235. Crossref, ISI, Google ScholarYang, W., et al. 2018. Australasian Plant Dis. Notes 13:12. Crossref, Google ScholarThe author(s) declare no conflict of interest.Funding: Funding was provided by China National Tobacco Corporation (110201601025(LS-05) and 110201502003) and Guizhou Tobacco Corporation (201711).DetailsFiguresLiterature CitedRelated Vol. 103, No. 12 December 2019SubscribeISSN:0191-2917e-ISSN:1943-7692 DownloadCaptionChlorotic symptom of Paris polyphylla var. yunnanensis infected by PMMoV-QJ (Wen et al.). Photo credit: M. F. Zhao. Symptoms of Puccinia triticina on wheat (Brar et al.). Photo credit: G. S. Brar. Metrics Article History Issue Date: 21 Nov 2019Published: 26 Sep 2019First Look: 1 Aug 2019Accepted: 24 Jul 2019 Pages: 3276-3276 Information© 2019 The American Phytopathological SocietyFundingChina National Tobacco CorporationGrant/Award Number: 110201601025(LS-05)Grant/Award Number: 110201502003Guizhou Tobacco CorporationGrant/Award Number: 201711Keywordsfungidisease managementpathogen detectionepidemiologydisease development and spreadThe author(s) declare no conflict of interest.

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