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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Mycology and Nematology Genetic Diversity and Biology Laboratory » Research » Publications at this Location » Publication #421183
Research Project: Fungal Systematics and Diagnostic Resource Development for Safeguarding Plant Health

Location: Mycology and Nematology Genetic Diversity and Biology Laboratory

Title: First observation of Peronospora digitalis causing downy mildew on Culver’s root (Veronicastrum virginicum) in the USA

Author
item Salgado-Salazar, Catalina
item HUDELSON, BRIAN - University Of Wisconsin

Submitted to: Journal of Plant Diseases and Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/13/2024
Publication Date: 12/14/2024
Citation: Salgado-Salazar, C., Hudelson, B. 2024. First observation of Peronospora digitalis causing downy mildew on Culver’s root (Veronicastrum virginicum) in the USA. Journal of Plant Diseases and Protection. 132. Article e54. https://doi.org/10.1007/s41348-024-01055-0.
DOI: https://doi.org/10.1007/s41348-024-01055-0

Interpretive Summary: Downy mildews cause some of the most severe and destructive diseases of ornamental plants, impacting both the yield and the quality of the final product. However there are many knowledge gaps concerning their identity. This study used DNA sequences and microscopy to describe the first observation of downy mildew disease on the ornamental Culver's root in the U.S. The results of this study have important implications for production and disease management. The information from this study will be useful to plant pathologists, regulatory officials and others involved in the management of plant health in the ornamental plant industry.

Technical Abstract: The genus Peronospora (Oomycota, Peronosporales) is an obligate biotrophic group of pathogens that cause downy mildew in a wide array of plants of economic or ecological importance. In August 2024, Culver’s root plants (Veronicastrum virginicum) growing at a commercial nursery in Wisconsin, USA, were found showing symptoms and signs of infection by an unknown downy mildew species in the genus Peronospora. In this study, using morphological and molecular data analyses of one mitochondrial (cox2) and two nuclear (ITS and nrLSU) loci, we could identify Peronospora digitalis as the species infecting V. virginicum. Peronospora digitalis primarily infects plants in the genus Digitalis, such as D. purpurea, resulting in significant damage. This study represents the first observation of P. digitalis in a host genus other than its primary one, highlighting the risks these pathogens pose for plant health by increasing the potential for crop losses due to lack of prevention, management and mitigation strategies.