Three-year update on Ribes susceptibility to white pine blister rust

Accessions for 55 Ribes species were evaluated for presence of uredia of white pine blister rust (WPBR), Cronartia ribicola Fischer, during the fall of 1995, 1996, and 1997 after natural infection. Incidence varied by year, within taxonomic sections, and between and within species. The number of infected accessions was greatest in 1997, the autumn with the most precipitation. During this study, 36 species were observed to be infected with WPBR; 19 had no observable uredia. Some species may contain new sources of genes for developing additional rust-resistant commercial Ribes cultivars. For the cultivars, about 82 % of the black currant (R. nigrum L.); about 27% of the red, white and pink currants (R. rubrum L.); 15% of the gooseberries (R. uva-crispa L. and R. oxyacanthoides L.); 13% of the black currant x gooseberry hybrids (R. x nidigrolaria Bauer) had uredia of C. ribicola. Further studies should be conducted to confirm WPBR resistance of cultivars and species through artificial inoculation.