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James A. Chatfield, Ohio State University Extension, Northeast District/Horticulture and Crop Science; Nancy A. Taylor, Erik A. Draper, Stephen Nameth, Joseph F. Boggs, |
Daylily rust, caused by the fungus Puccinia sp., was identified in the state of Ohio for the first time in the summer of 2001. The disease was originally found in the southern United States in 2000 and more recently found in Kentucky and Indiana.
Depending on the daylily variety, foliar symptoms can range from very severe to mild. Spores of the causal fungus can germinate and infect the host particularly during periods of high moisture.
The fungus also has a secondary weed host, Patrinia sp. There are about six species of Patrinia that are grown in the United States as ornamental plants. The fungal spores are spread from plant to plant by human contact, wind, and wind-driven rain. One week to 10 days following infection the affected leaves become covered with pustules of rust-colored spores. These new spores can then act as a source of infection for other daylilys.
Plants suspected of rust infection should be sampled and sent to a university or state diagnostic clinic for proper identification. In some cases, rust can be confused with leaf-streak disease. A variety of fungicides have been recommended for rust disease management. These include Banner MAXX, Heritage, Contrast, and Systhane. Infected plants should be removed (cut-back) of symptomatic leaves prior to fungicide application. Symptomatic leaves need to be destroyed.
Research is being conducted at the Ohio State University on the overwintering capabilities of the rust spores in the northern latitudes. In the spring of 2002, field trials will be conducted on the Waterman complex under the direction of Mac Riedel and Steve Nameth to determine fungicide efficacy and varietal differences in susceptibility to this potentially destructive disease.