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First Report of Tar Spot on Corn Caused by Phyllachora maydis in Georgia, United States

2022; American Phytopathological Society; Volume: 106; Issue: 8 Linguagem: Inglês

10.1094/pdis-11-21-2456-pdn

1943-7692

Laxmi Pandey, Caroline Ann Burks, Luisa F. Gómez, Larry Newsom, J. Brock, Robert C. Kemerait, Marin T. Brewer,

Plant and Fungal Interactions Research

HomePlant DiseaseVol. 106, No. 8First Report of Tar Spot on Corn Caused by Phyllachora maydis in Georgia, United States PreviousNext DISEASE NOTE OPENOpen Access licenseFirst Report of Tar Spot on Corn Caused by Phyllachora maydis in Georgia, United StatesLaxmi Pandey, Caroline Ann Burks, Luisa Gómez Londoño, Larry Newsom, Jason H. Brock, Robert C. Kemerait, and Marin Talbot BrewerLaxmi PandeyDepartment of Plant Pathology, University of Georgia, Athens, GA 30602, Caroline Ann BurksDepartment of Plant Pathology, University of Georgia, Athens, GA 30602, Luisa Gómez LondoñoDepartment of Plant Pathology, University of Georgia, Athens, GA 30602, Larry NewsomBASF, Tifton, GA 31794, Jason H. BrockDepartment of Plant Pathology, University of Georgia, Tifton, GA 31793, Robert C. KemeraitDepartment of Plant Pathology, University of Georgia, Tifton, GA 31793, and Marin Talbot Brewer†Corresponding author: M. T. Brewer; E-mail Address: mtbrewer@uga.eduhttps://orcid.org/0000-0002-7064-6021Department of Plant Pathology, University of Georgia, Athens, GA 30602 AffiliationsAuthors and Affiliations Laxmi Pandey1 Caroline Ann Burks1 Luisa Gómez Londoño1 Larry Newsom2 Jason H. Brock3 Robert C. Kemerait3 Marin Talbot Brewer1 † 1Department of Plant Pathology, University of Georgia, Athens, GA 30602 2BASF, Tifton, GA 31794 3Department of Plant Pathology, University of Georgia, Tifton, GA 31793 Published Online:20 Jul 2022https://doi.org/10.1094/PDIS-11-21-2456-PDNAboutSectionsPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Tar spot is a major foliage disease of corn (Zea mays) caused by the fungus Phyllachora maydis. This disease can reduce the quality of silage, stover, husks, and grain (Valle-Torres et al. 2020). It was identified in the United States for the first time in 2015 in northern Illinois and Indiana (Ruhl et al. 2016). As of 2020, it has also been confirmed in Iowa, Michigan, Wisconsin, Ohio, Florida, Missouri, Minnesota, and Pennsylvania (Collins et al. 2021; Telenko et al. 2020). In early August 2021, tar spot symptoms and signs were observed in late-planted, hybrid corn in southwestern Georgia in both Tift and Calhoun Counties. Where it occurred, incidence was nearly 100%, and severity ranged from approximately 1 to 20% leaf coverage. As of November 2021, tar spot has been confirmed in 13 counties throughout southern Georgia. The symptoms on leaves were chlorotic lesions, and the signs were black, raised, and circular to irregular-shaped structures (stromata or clypei) ranging from 0.2 to 8 mm on the surface of the leaves. The stromata were present on both green and necrotic leaf tissue. Southern corn rust (Puccinia polysora) was often, but not always, observed on leaves with tar spot. Microscopic observations of stromata included single and clustered ascomata (60 × magnification) that contained cylindrical, unitunicate asci with ellipsoid, hyaline, and aseptate ascospores and abundant filiform paraphyses (400 × magnification). For molecular confirmation, stromata were surface sterilized with 95% ethanol and separated from the leaf tissue, and DNA was then extracted using the Qiagen DNeasy Plant Mini-Kit (Qiagen, Inc., Valencia, CA). PCR was conducted with the universal ITS1 and ITS4 primers to amplify the internal transcribed spacer (ITS) region of the rDNA. The amplicons were Sanger sequenced (Genewiz, Inc., South Plainfield, NJ), and a consensus sequence of a representative lesion was deposited in GenBank (accession number OK649959). Using the BLASTn algorithm, our sequence shared 100 and 99.2% coverage and 97.2 and 98.4% similarity to P. maydis GenBank accessions MG881848 and MK184990, respectively. P. maydis is an obligate parasite that cannot be cultured, so Koch’s postulates were not performed. Inoculum of P. maydis may have been transported to Georgia from Florida by wind or other weather events, but this has not been confirmed.The author(s) declare no conflict of interest.References:Collins, A. A., et al. 2021. Plant Dis. 105:2244. https://doi.org/10.1094/PDIS-11-20-2456-PDN Link, ISI, Google ScholarRuhl, G., et al. 2016. Plant Dis. 100:1496. https://doi.org/10.1094/PDIS-12-15-1506-PDN Link, ISI, Google ScholarTelenko, D. E. P., et al. 2020. Mol. Plant-Microbe Interact. 33:884. https://doi.org/10.1094/MPMI-03-20-0075-A Link, ISI, Google ScholarValle-Torres, J., et al. 2020. Plant Dis. 104:2541. https://doi.org/10.1094/PDIS-02-20-0449-FE Link, ISI, Google ScholarThe author(s) declare no conflict of interest.DetailsFiguresLiterature CitedRelated Vol. 106, No. 8 August 2022SubscribeISSN:0191-2917e-ISSN:1943-7692 Download Metrics Article History Issue Date: 29 Jul 2022Published: 20 Jul 2022First Look: 25 Jan 2022Accepted: 22 Jan 2022 Page: 2262 Information© 2022 The American Phytopathological SocietyKeywordscornfungiobligate biotrophtar spotThe author(s) declare no conflict of interest.PDF download