Disease Note Diseases Caused by Fungi and Fungus-Like Organisms First Report of Stagonosporopsis heliopsidis Causing a Leaf Spot on Whorled Sunflower, Helianthus verticillatus, in the United States S. L. Boggess, 1,† E. C. Bernard, 1 A. S. Windham, 2 and R. N. Trigiano 1 1 Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996 2 Department of Entomology and Plant Pathology, University of Tennessee, Nashville, TN 37211 Funding: Funding was provided by USDA-MOA-NACA (586062-006). Plant Dis. XXX:XX, XXXX; published online as https://doi.org/10.1094/ PDIS-11-21-2568-PDN. Accepted for publication 13 January 2022. Whorled sunflower, Helianthus verticillatus Small (Asteraceae), is a feder- ally endangered species (U.S. Fish and Wildlife Service 2014) growing in only a few locations in Tennessee, Georgia, Mississippi, and Alabama (Ellis et al. 2008; Matthews et al. 2002) and recently in Virginia (Edward Schilling, personal communication) in the United States. This herbaceous perennial pro- duces yellow, daisy-like inflorescences from September through October and is of interest for use in landscapes because the flowers attract numerous native bees and other insects (Edwards et al. 2020; Strange et al. 2020; Trigiano et al. 2021). In May 2021, black necrotic spots surrounded by chlo- rotic halos appeared on various locations on the blade of mature leaves on landscape plants in Knoxville, TN. Symptomatic leaves were washed in run- ning water for 10 min, surface-sterilized with 1.25% NaOCl for 8 min, and rinsed with sterile, distilled water. Lesions were excised with some healthy tissue, cultured on potato dextrose agar (PDA) augmented with 10 mg/liter of rifampicin, and incubated at room temperature. White to dark-brown hyphae grew from the lesions and were transferred to fresh medium until pure cul- tures were obtained. Cream-colored and slightly pinkish spore masses were evident after 10 weeks of culture. Conidia were cylindrical and ellipsoidal to subglobose at one end. The mean dimensions of conidia were 5.4 μm (3.9 to 6.8 μm) in length and 2 μm (1.7 to 2.5 μm) in width (n = 20). Conidia matched the description of Stagonosporopsis heliopsidis (formally Phoma heliopsidis and Phyllosticta heliopsidis) (Chen et al. 2015). The morphology of the conidia from S. heliopsidis differs slightly from the globose conidia of its closely related sister species, S. helianthi (Chen et al. 2015). PCR was per- formed with ITS1 and ITS4 primers (White et al. 1990) using the Phire Direct Plant PCR kit (ThermoFisher Scientific, Waltham, MA) and sequenced at a commercial sequencing center. The sequences were concatenated into one consensus and identified as S. heliopsidis with a 100% match to GenBank number GU237924.1. A sequence was deposited in GenBank with accession number OK315471. Koch’s postulates were completed using detached leaf assays because H. verticillatus is an endangered species and only a few plants were available. Five surface-sterilized, symptomless, sign-free leaves were dis- sected bilaterally, and halves were placed individually on 1.5% water agar supplemented with 10 mg of rifampicin/liter. Mycelial plugs grown on PDA were positioned in contact with one half-leaf, and the remaining half-leaf was treated with a sterile PDA plug as a control. Cultures were incubated for 7 days at room temperature in ambient light. All control halves of the leaves remained green and healthy, whereas the inoculated leaves developed lesions with the same appearance as lesions on the whole plant. The pathogen was reisolated using the protocol described previously and sequenced (OK315470). This fungus causes very limited aesthetic damage to leaves but does not affect the growth and flowering of ornamental plantings of H. verticillatus. To our knowledge, this is the first report of S. heliopsidis on H. verticillatus in the United States. References: Chen, Q., et al. 2015. Stud. Mycol. 82:137. Edwards, T., et al. 2020. Front. Genet. 11:410. Ellis, J. R., et al. 2008. Heredity 100:574. Matthews, J. F., et al. 2002. Castanea 67:13. Strange, C., et al. 2020. HortSci. 55:1980. Trigiano, R. N., et al. 2021. Plants 10:1565. U.S. Fish and Wildlife Service. 2019. Fed. Regist. 79:50990. https://www.fws.gov/ policy/library/2014/2014-19558.html White, T. J., et al. 1990. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA. The author(s) declare no conflict of interest. e-Xtra Keywords: cultivar/resistance, disease management, fungi, herbaceous/ flowering plants, ornamentals, pathogen detection † Indicates the corresponding author. S. L. Boggess; sbogges1@utk.edu © 2022 The American Phytopathological Society Plant Disease / 1