Released: June 26, 2001

New Daylily Disease Confirmed in Kansas

MANHATTAN, Kan. – A daylily disease from Asia has made its way into Kansas. The Kansas Department of Agriculture confirmed in mid-June the fungus-caused rust has infected a single daylily, bought in Florida and planted in northeast Kansas.

"I suspect, however, this is only the first of many reports to come," said Ned Tisserat, plant pathologist at Kansas State University. "Daylily rust can develop very rapidly. The fungus produces an abundance of spores, which can move in the wind. The entire infection process can take just two to three days."

The disease first showed up in the United States last year. Officials confirmed its presence in several Southern nurseries, which already had shipped infected plant divisions to other regions.

Some daylily varieties are proving to be more susceptible than others, Tisserat said. The varieties most at risk include Stella de Oro – a medium-sized perennial widely grown in Kansas, not only for its cheerful gold-yellow flowers but also for its ability to keep producing blooms from June through frost.

Other vulnerable varieties include Attribution, Pardon Me, Gertrude Condon, Crystal Tide, Colonel Scarborough, Starstruck, Joan Senior, Imperial Guard, and Double Buttercup.

"Kansas’ first case was on a cultivar appropriately named Save Our Soul," Tisserat said.

The disease causes one-eighth-inch-wide blisters or raised spots that are bright yellow-orange. These spots develop on both sides of affected leaves – each of which may have dozens.

"The pustules contain orange, dusty spores that you can easily rub or blow off the leaf surface. Those spores are what infect other leaves," Tisserat said. "As the disease progresses, entire daylily leaves lose their green coloration, while drying up."

No U.S. fungicide is labeled for the disease’s control, but some general-use fungicides are testing out as fairly effective, he said.

"Given the nature of the disease, however, Kansans should simply dig up any daylily that exhibits these symptoms and put it in a plastic bag they can seal or tie," Tisserat advised.

Kansans can deliver such whole-plant "samples" to their county’s K-State Research and Extension office. The agents there will contact the proper division in the Kansas Department of Agriculture, plus can forward samples to K-State’s Plant Disease Diagnostic Lab in Manhattan.

The rust also can infect a perennial called Patrinia – six species of which are grown and sold in the United States. Reports from Asia suggest it can infect hostas, as well, but U.S. inoculation studies have not backed that up, Tisserat said.

"That’s the only good news we’ve gotten about this disease," he added. "Additional hosts would increase the severity of the rust infections."

Daylily rust may have obvious symptoms, but they don’t show in plant shipments.

"Shipped plants tend to arrive with few or no leaves. Often, they’re just a crown and some roots," Tisserat explained. "We don’t know how the fungus is hitching a ride. In any case, the disease symptoms rarely show up until several weeks after planting, when new leaves are up and growing."

Scientists’ best guess so far is that the disease first made its way from Asia to Central or South America. Plant shipments from there carried the fungus into the United States – where most growers have never seen the disease and may be slow to recognize its serious potential, the plant pathologist said.

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K-State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well-being of Kansans. Supported by county, state, federal and private funds, the program has county Extension offices, experiment fields, area Extension offices and regional research centers statewide. Its headquarters is on the K-State campus, Manhattan.

Story by:
Kathleen Ward, Communications Specialist
kward@oznet.ksu.edu
K-State Research& Extension News