Puccinia hemerocallidis, Cause of Daylily Rust, a Newly Introduced Disease in the Americas

Area of Science:

• Plant Pathology
• Mycology
• Botany

Background:

• A rust disease affecting daylilies (Hemerocallis spp.) has recently emerged in North and Central America.
• Accurate identification of plant pathogens is crucial for effective disease management and quarantine efforts.

Purpose of the Study:

• To confirm the identity of the daylily rust introduced into the Americas.
• To provide a modern morphological description of the rust, including its uredinial and telial stages.

Main Methods:

• Morphological examination of numerous rust specimens from Costa Rica and the United States.
• Comparison of these specimens with international collections from Asia.
• DNA sequencing of the internal transcribed spacer (ITS) region of ribosomal DNA from representative specimens.

Main Results:

• Morphological characteristics of the rust from the Americas matched those of Puccinia hemerocallidis found in Asia.
• DNA sequence data further supported the identification of the rust as Puccinia hemerocallidis.
• Illustrations of the uredinial and telial stages were generated.

Conclusions:

• The rust recently introduced into North and Central America is confirmed to be Puccinia hemerocallidis.
• This confirmation aids in understanding the epidemiology and spread of daylily rust.
• A comprehensive description facilitates future identification and management strategies.