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Puccinia hemerocallidis, cause of daylily rust, a newly introduced disease in the Americas
  Jose R. Hernandez, Mary E. Palm, and Lisa A. Castlebury
 
Daylily rust has become prevalent in the Americas over the last two years, being previously found only in Asia. The purpose of this project was to determine if the rust in the Americas is the same or different from that in Asia
Results: Teliospores and urediniospore sizes varied among specimens but statistical analyses indicated that there was no significant difference in size between the Asian and the American spores. Three synapomorphies (including one indel) were present in the ITS region that distinguished the two Asian specimens from the four American specimens. However the ITS variation within the American or Asian specimens was approximately equal to variation between the specimens from the two broad geographic areas. The rust introduced into the Americans is Puccinia hemerocallidis.
A. Heavily infected potted daylily plant with uredinia B. Mature uredinial sori with numerous yellow urediniospores on abaxial leaf surface C. Chlorotic leaf with few yellowish-brown, erumpent uredinia surrounded by a green halo D. Surface view of echinulate urediniospores
E. Median view of urediniospores in Fig. D F. Dark, erumpent telia on chlorotic and necrotic leaf G. Non-septate (mesospores) and one-septate teliospores H. Mesospores, common in American collections
Daylily rust caused by Puccinia hemerocallidis
A. Heavily infected potted daylily plant with uredinia.
B. Mature uredinial sori with numerous yellow urediniospores on abaxial leaf surface.
C. Chlorotic leaf with few yellowish-brown, erumpent uredinia surrounded by a green halo.
D. Surface view of echinulate urediniospores.
E. Median view of urediniospores in Fig. D.
F. Dark, erumpent telia on chlorotic and necrotic leaf.
G. Non-septate (mesospores) and one-septate teliospores.
H. Mesospores, common in American collections. Bar = 10 µm
Materials and Methods: Numerous specimens from Costa Rica and the United States were examined morphologically and compared with specimens from China, Japan, Russia, and Taiwan, including the type specimen from Siberia. In addition, the ITS region of the ribosomal DNA was sequenced from six representative fresh specimens from the Americas and Asia.
These sites have additional information on daylily rust
José Hernández and Lisa Castlebury - USDA, Agricultural Research Service, Systematic Botany and Mycology Laboratory (ARS, SBML) Beltsville, MD 20705-2350.
Mary Palm - USDA, Animal and Plant Health Inspection Service (APHIS), SBML, Beltsville, MD 20705-2350
 
Part of a poster presented at the VII International Mycological Congress, Oslo, Norway 2002.