Mycological Progress

, Volume 17, Issue 12, pp 1283–1291 | Cite as

Basidiophora delawarensis, a new downy mildew species infecting cultivated goldenrod (Solidago sphacelata) in the USA

  • Emma C. Wallace
  • Catalina Salgado-Salazar
  • Nancy F. Gregory
  • Jo Anne CrouchEmail author
Original Article


Species in the genus Basidiophora (Oomycota, Peronosporales) are pathogens causing downy mildew disease on several closely related plant hosts in the family Asteraceae, including the genera Conyza, Erigeron, Solidago, and Symphyotrichum. Despite their widespread occurrence, little is known about the diversity, biology, and economic impact of downy mildew pathogens of ornamental or wild plants in the Asteraceae. In June 2017, Solidago sphacelata plants of the cultivar ‘Golden Fleece’ were found in the state of Delaware, USA, showing typical symptoms of downy mildew disease. Initial morphological observations indicated the specimen belonged to the genus Basidiophora. Phylogenetic analysis of a sequence matrix of the partial cox2 mitochondrial gene using Bayesian and maximum likelihood methods showed that the Basidiophora isolate from S. sphacelata represents an undescribed species that is here described as B. delawarensis. This new species constitutes the third accepted species in the genus Basidiophora and can be distinguished from other Basidiophora species by differences in size of sporangia and sporangiophores and nucleotide sequence divergence. This new species poses a potential threat to its host, warranting close monitoring and the implementation of disease management programs.


Asteraceae coxHerbaceous perennials Oomycota Peronosporaceae Systematics Taxonomy 



This work was funded by the USDA-APHIS Farm Bill 10007 program, USDA-ARS project 8042-22000-298-00-D, and by the appointments of E. Wallace and C. Salgado-Salazar to the ARS Research Participation Program administered by the Oak Ridge Institute for Science and Education (ORISE) through an interagency agreement between the U.S. Department of Energy (DOE) and the USDA. ORISE is managed by ORAU under DOE contract number DEAC05-06OR23100. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the USDA. The USDA is an equal opportunity provider and employer.


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Copyright information

© This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply 2018

Authors and Affiliations

  • Emma C. Wallace
    • 1
    • 2
  • Catalina Salgado-Salazar
    • 1
    • 2
  • Nancy F. Gregory
    • 3
  • Jo Anne Crouch
    • 1
    Email author
  1. 1.Mycology and Nematology Genetic Diversity and Biology LaboratoryUSDA-ARSBeltsvilleUSA
  2. 2.Oak Ridge Institute for Science and EducationOak RidgeUSA
  3. 3.Department of Plant and Soil SciencesUniversity of DelawareNewarkUSA

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