|MOLLOV, DIMITRI - University Of Minnesota|
Submitted to: Disease Note
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2012
Publication Date: 2/1/2013
Citation: Stoxen, S.M., Mollov, D., Szabo, L.J. 2013. First Report of Veronica Rust by Puccinia veronicae-longifoliae in Minnesota on Veronica spicata Royal Candles. Disease Note. 97:285.
Interpretive Summary: Several species of Veronica are popular perennials used in garden landscapes. In 2008, spiked speedwell (Veronica spicata) in a Minnesota nursery exhibited typical symptoms of veronica rust. Characterization of teliospore morphology and DNA sequence analysis of a segment of the nuclear ribosomal RNA region confirmed that the identity of the pathogen as P. veronicae-longifolia. This represents the first observation of veronica rust in Minnesota. This disease can cause significant foliar blighting and if not managed properly can cause complete loss of the nursery veronica crop. In 2004, veronica rust was found in a commercial nursery in Michigan, representing the first documented case in the U.S. Since then, veronica rust has been observed sporadically in Michigan (2005 and 2011) as well as in a nursery in Connecticut. Veronica rust pathogen is not considered a quarantine significant pest by The Animal and plant Health Inspection Service. These results will be used by Agricultural Professionals and Plant Pathologists.
Technical Abstract: In September 2008, Veronica spicata Royal Candles plants showing foliar symptoms typical of a rust infection were brought to the Plant Disease Clinic at the University of Minnesota by a commercial nursery. A dark brown discoloration was apparent on the upper surface of the leaf with lighter brown pustules on the underside. Teliospores collected from the pustules were 2-celled with smooth walls and measured 36.35-48.87 µm in length, 11.96-18.28 µm in width and had a wall thickness of 1.33-2.61 µm, which is in accordance with type specimen of Puccinia veronicae-longifoliae. Pathogen identity was confirmed by comparison of the DNA sequence of nuclear ribosomal RNA region containing the internal transcribed spacer regions 1 and 2, 5.8S and the 5’ end of the 28S subunits between herbarium samples from the U.S. National Fungus Collection (BPI 841971/Genbank Accession JQ627617 and BPI 871789/ Genbank Accession JQ627618) and the collected specimen (BPI 882886/ Genbank Accession JQ627616). P. veronicae-longifoliae was first reported in the United States in 2004 from a commerical nersery in Michigan. Veronica rust was found again 2005 and 2011 in Michigan. The only other known report of veronica rust in the United States occurred in Connecticut in 2007. P. veronicase-longifolia is not considered a quarantine significant pest by The Animal and Plant Health Inspection Service due to the limited host range, the host not being on the threatened or endangered list and the host being of little economic or environmental importance.