8/13/01

Contacts:
Mark Gleason, Plant Pathology, (515) 294-0579
Brian Meyer, Agriculture Communications, (515) 294-0706

DAYLILY DISEASE SPOTTED IN IOWA FOR THE FIRST TIME

AMES, Iowa -- Lovers of Iowa's daylilies could have a serious problem on their hands -- a new disease that's been spotted in the state for the first time.

The disease also might infect other herbaceous perennial plants, including the popular hosta.

In the past week, daylily rust was found on daylilies in the eastern Iowa towns of West Liberty and Atalissa. "In both cases, the source of the rust was plants shipped from a Florida nursery," said Mark Gleason, extension plant pathologist at Iowa State University.

"The disease won't kill daylilies, but it will make them ugly," Gleason said. "As symptoms progress, leaves turn yellow and dry up."

Daylily rust is caused by a fungus, Puccinia hemerocallidis. Prior to last year, the fungus was reported only in Asia, the ancestral home of daylilies. Last year the disease was first spotted in the southeastern United States. Since then, the disease has spread on nursery stock to 17 states, including Minnesota and Kansas.

Now, add Iowa to the list.

"The most obvious symptoms are yellow to brown streaks on the leaves," said Gleason. "You'll also see many small orange or yellow spots poking from the leaf surface. These pustules pop open and release dusty, orange-colored spores."

Gleason said it's easy to confuse daylily rust with two look-alike problems - daylily leaf streak, which is caused by another fungus, and feeding by aphids. Both will also cause leaf streaking. The difference is the rust's pustules. "If you gently rub the leaves with your finger or against white paper and they leave an orange streak, it's rust," he said.

The fungus can spread quickly. "Once in a nursery or a landscape bed, infected plants can quickly churn out vast quantities of spores, which can spread on wind currents for long distances," Gleason said. "Many daylily varieties are susceptible. The good news is that some appear to be at least partially resistant. But a list of resistant cultivars hasn't been developed yet."

Daylily rust can infect other plants, too, including a perennial called Patrinia and possibly hosta. So far, no infections of those plants have been reported in Iowa, Gleason said.

Here's what to do if you find daylily rust: Remove the infected foliage and burn or bury it. Afterward, sterilize your shears with 70 percent alcohol or 10 percent bleach or Lysol to prevent the spread of spores. If you removed the foliage by hand, wash your hands or gloves thoroughly.

Save a few leaves and either bring them to your county extension office or mail them directly to ISU's Plant Disease Clinic, 351 Bessey Hall, Iowa State University, Ames 50011. "We'd like to track the extent of the problem in Iowa and those samples will help us do it," said Gleason. People who find daylily rust also can contact Gleason by phone, (515) 294-0579, or e-mail, mgleason@iastate.edu.

Gleason said new foliage can be protected as it emerges by spraying with systemic fungicides such as propiconazole (Banner MAXX), azoxystrobin (Heritage), flutolanil (Contrast) or myclobutanil (Systhane, Eagle). "Be sure the product is labeled for either daylilies or ornamentals in general," he said.

Nobody knows yet whether the fungus can survive an Iowa winter. "More than likely, daylily rust will be added to the list of obnoxious pests that have invited themselves into our landscapes," Gleason said.

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