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: 9/18/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Epidemics caused by the bean rust fungus are responsible for serious losses in snap and dry bean production, losses to farmers, market instability, and consumer price increases. A few fungicides control bean rust, but host resistance is economically and environmentally preferable. The great variability of this rust fungal pathogen has made resistance that will remain effective over time and distance difficult to achieve. Locations and severity of 1995 United States bean rust epidemics are reported. Results are summarized from multi-location, cooperative field evaluations of the relative resistance/susceptibility of 41 snap and 17 dry bean breeding lines from three private and four public breeders. Subsequent greenhouse evaluations indicate that 36 of the 37 snap bean lines that were resistant at all field locations are resistant to all available races, deriving their resistance from Beltsville-released germplasm. However, only two newly released Beltsville entries of the nine dry bean lines that were resistant at all field locations are resistant to all races in the greenhouse. Newly identified races of the rust fungus at Beltsville in 1995 included five from Egypt, eight from Honduras, four from South Africa. All Beltsville releases are resistant to these new races as well as to previously identified races, but recommendations are made to breeders for Beltsville-released snap bean germplasm lines which are best for resistant cultivar development. Rust resistance in beans will improve production efficiency, market stability, food supply dependability, and reduction in fungicide use, benefitting growers and consumers. Technical Abstract: Significant losses from bean rust, caused by Uromyces appendiculatus occurred in six of the leading edible bean producing states of the United States in 1995. Among 41 snap bean and 17 dry bean breeding lines from seven breeders that were tested in three snap bean or four dry bean production areas and Beltsville, 37 snap bean lines and nine dry bean lines were resistant at all locations where tested. Greenhouse tests with multiple races indicated that 36 of the snap beans, but only two of the dry bean lines are resistant to all races. The two dry bean lines are recent Beltsville releases and all 36 of the snap bean lines are derived from Beltsville releases. Breeders are advised to use the more recent, rust resistant snap bean releases that derive resistance from Mexico 235 or certain plant introductions. From many field collections from Africa, Honduras, and the United States, 18 new races of the rust fungus were identified. Resistant plant introductions and germplasm releases are resistant to all 18 of these races. |
