July 18, 2001

Daylily rust disease was identified for the first time in Kentucky on July 16. This disease is a threat to the popular Kentucky garden plant grown by homeowners, nurserymen and others.

"The specimen came from a Fayette County non-commercial day lily grower who buys plants from the south, said John Hartman, Extension plant pathologist for the University of Kentucky College of Agriculture. "We have notified USDA officials (through our USDA APHIS Kentucky Nursery Inspectors housed here at UK) as to what, if anything, needs to be done about the diseased plants to keep the disease from spreading."

In the July issue of Kentucky Pest News, there was an article about Daylily rust being found for the first time in North America last year in Florida. Since then, it has been spread, mainly in infected nursery plant material to several other states including Alabama, California, Georgia, Kansas, Louisiana, Minnesota, Mississippi, South Carolina, Tennessee, Texas and now, Kentucky.

"The causal agent is Puccinia hemerocallidis, a rust fungus," Hartman said. "The disease is identified by bright yellow or orange colored spots with raised pustules on the foliage of affected plants and by orange colored spores which emerge from the pustules. As symptoms progress, leaves turn yellow and dry up."

The following web site shows good pictures of this and other daylily diseases and disorders: http://www.ncf.ca/~ah748/rust.html

Hartman believes the disease will become a serious pest of day lilies. Daylily rust disease is easily spread in the nursery trade since viable spores may be carried long distances on plants and propagative material not showing symptoms.

If you suspect daylily rust, immediately remove all infected foliage and burn or bury the clippings after saving a leaf or two to send to your county Extension office. Extension agents can send them to the UK plant disease diagnostic laboratory.

"Most County Extension Agents will recognize rust disease and would be able to tell the homeowner immediately whether daylily rust is present, or if it is suspected," Hartman said.

After removing diseased foliage, sterilize tools with 70 percent alcohol, 10 percent bleach, or Lysol to prevent spread. Wash your hands, gloves, or clothes afterwards, if necessary, to keep the disease from spreading to the rest of the garden.

"New foliage can be protected as it emerges with fungicides such as propaconizole (Banner Maxx), azoxystrobin (Heritage), flutolonil (Contrast), or myclobutanil (Systhane, Eagle)," Hartman suggested. "Because this is a new disease, there is no specific label for daylily rust."

Hartman said to make sure the label indicates the fungicide product used can be used on daylilies or on ornamentals generally in the nursery or landscape. Resistant cultivars have not yet been identified.

Mostly Hartman wants to urge agents, homeowners and nurserymen to be on the lookout for this potentially serious disease of daylily.


John Hartman 859-257-9764