Diamonds in the Rust: RibesResistance to White Pine Blister Rust

Abstract

White pine blister rust (WPBR), Cronartia ribicolaFischer, causes economic damage to white pines, Pinus strobusL., and infects leaves of some Ribeslate in the summer after harvest. Susceptible Ribesand Pinusserve as obligate alternate hosts for this disease. The objective of this study was to determine the response of Ribesspecies and cultivars to WPBR under field conditions at Corvallis, OR, where inoculum is naturally present. In 1995 and 1996, 54 Ribestaxa from North and South America, Europe, and Asia, were visually evaluated August through October for the presence of uredia on the abaxial leaf surfaces. Plants with no observable uredia for the duration of the study were considered resistant. WPBR infection varied by year, within taxonomic sections, and between and within species. Uredia of WPBR were present on 22 Ribestaxa in one or both years, while 32 others were resistant, i.e., had no uredia. Some of the resistant Ribesspecies were native outside of eastern Russia, which is the native range of the rust. Resistant species may contain new sources of genes for developing additional rust-resistant commercial Ribescultivars. The cultivation of resistant Ribesis an alternative to consider where state statutes banning the genus are under review.