Author
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Stavely, J |
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Submitted to: Bean Improvement Cooperative Annual Report
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 5/5/1998 Publication Date: N/A Citation: N/A Interpretive Summary: Disease epidemics caused by the bean rust fungus in edible snap and dry beans cause losses in production, losses to farmers, market instability and consumer price increases. A few fungicides control rust, but resistance in the host crop is economically and environmentally preferable. The great variability of the rust pathogen makes resistance that will remain effective over time and distance difficult but important to achieve. Locations and severities of 1997 United States bean rust epidemics are reported. Results are summarized from multi-location field evaluations of relative resistance/susceptibility of 33 snap and 43 dry bean breeding lines or new cultivars from five private and seven public breeders. Greenhouse evaluations of the most resistant entries from all field tests indicated that 10 of 11 snap bean lines and five of 11 dry bean lines or cultivars that were resistant at all field locations were also resistant to all 87 available races of the rust fungus and derive their resistance from Beltsville-released germplasm. Field rust collections analyzed in 1997 and early 1998 produced no new pathogenic races of the fungus with significant new virulence for important resistance genes or germplasm releases. Rust resistance in beans will improve production efficiency, market stability and food supply dependability, and will reduce pesticide usage. Technical Abstract: Losses from bean rust, caused by Uromyces appendiculatus, were moderate to severe on susceptible cultivars in some scattered dry bean production areas, but were generally light in both dry and snap beans in 1997 in the United States. Among 33 snap bean lines and 43 dry bean lines or cultivars that were field tested in three snap bean and four dry bean production areas and Beltsville, 11 snap bean lines and 11 dry bean lines or cultivars were rust resistant at all locations. Greenhouse testing, with multiple key pathogenic races of the rust fungus indicated that 10 of these snap bean lines and five of the dry bean lines or cultivars are resistant to all 87 available races of U. appendiculatus. All of the lines or cultivars resistant to all races are Beltsville releases or derivatives from Beltsville releases. Field rust collections obtained in 1997 from several locations in the United States and elsewhere were not virulent upon any of the major sources of host resistance or upon Beltsville germplasm releases. |
