Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/10/2002
Publication Date: N/A
Interpretive Summary: Daylilies are the most important perennial cultivated plant in the United States. In early 2001 a new rust disease of daylilies was reported from Georgia and has since spread throughout much of the United States. The newly reported rust is also known from Costa Rica where daylilies are grown in winter nurseries prior to shipment to the United States in spring. The cause of daylily rust is Puccinia hemerocallidis, a fungus that is native to eastern Asia including Siberia from where it was originally described. The daylily rust fungus is relatively obscure reported primarily in non-English journals. Research was needed to determine if the newly discovered fungus in the Americas was the same species as the rust on daylilies described from eastern Asia. Type and many additional specimens of daylily rust from eastern Asia and the Americas were examined microscopically. In addition, DNA and sequence data were obtained and compared for freshly collected specimens in Japan, Russia, Costa Rica and the United States. Based on the examination of fungal specimens and ITS sequences, it was determined that the daylily rust in the Americas is the same species as that in eastern Asia. In addition, a modern description of the daylily rust fungus is provided. This research will be used by plant pathologists, extension agents and plant regulatory officials to identify the daylily rust fungus.
Technical Abstract: Puccinia hemerocallidis, the cause of daylily rust, was recently introduced into North and Central America. In order to confirm the identity of the rust in the Americas and provide a complete description and illustrations of the uredinial and telial stages of P. hemerocallidis, fresh specimens from Costa Rica, Japan, Russia and the United States were examined morphologically. The ITS region of the ribosomal DNA was sequenced from six representative specimens from Asia and the Americas. Many additional herbarium specimens were examined for comparison of morphological characters. Teliospore and urediniospore measurements were analyzed to determine if differences among collections were statistically significant. A detailed description of P. hemerocallidis is provided.