In the late 1800s a European disease called white pine blister rust, Cronartia ribicola Fisher, was introduced into the United States. By 1937 this disease had naturalized and was firmly established in native Ribes across the country. White pine blister rust causes economic damage to white pines and infects leaves of some Ribes late in the summer after harvest. Ribes serve as obligate alternate hosts for this disease. Our objective was to determine which Ribes species were susceptible to white pine blister rust under field conditions in Corvallis, Ore., where inoculum is naturally present. In 1995 and 1996, 57 Ribes taxa from North and South America, Europe, and Asia, were evaluated in mid-August and mid-September for presence of white pine blister rust. Susceptibility was determined by the rust infection of the abaxial leaf surfaces. Rust infection was rated on a scale from 1, no infection observed, to 9, severe infection covering almost the entire surface of at least three or more leaves. Data from 1995 indicated that 22 Ribes taxa were susceptible to white pine blister rust, while 35 others had no infection. The 1996 data will be reported. Species without infection may offer resistance genes to breeders who wish to develop rust-resistant commercial fruit cultivars.
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