Seedling resistance to Phytophthora cinnamomi in the genus Abies

• Context Root rot and stem canker caused by Oomycete species belonging to the genus Phytophthora often seriously limit culture of true firs ( Abies spp.) • Aim An investigation of the variation of resistance among Abies species to Phytophthor a cinnamomi was carried out to identify potential sources of resistance in the genus. • Methods Thirty-two Abies species were grown in a greenhouse for 2 and/or 3 years from seed. Seedlings were moved to an outdoor lath house, inoculated with rice grains colonized with P. cinnamomi , and subsequent mortality was assessed biweekly for 16 weeks. • Results Disease developed rapidly resulting in 88.1 % overall mortality 16 weeks after inoculation. Mortality was less in two of the eight taxonomic sections of the genus evaluated, Momi (0.65 ± 0.0252) and Abies (0.79 ± 0.0193). Mortality in all other sections exceeded 93 %. Final species mortality ranged from 10.6 % ( Abies firma ) to 100.0 % (several species). • Conclusions Although several caveats apply, results have identified potential sources of Abies to be used as (1) resistant planting stock, (2) grafting rootstock, and (3) parents in hybridization/backcrossing programs in order to mitigate losses caused by P. cinnamomi .