GENETIC-PARAMETERS AND SELECTION EFFICIENCIES IN RESISTANCE TO WESTERN GALL RUST, STALACTIFORM BLISTER RUST, NEEDLE CAST, AND SEQUOIA PITCHMOTH IN LODGEPOLE PINE

Genetic variances, heritabilities, and between-trait genetic correlati ons in resistance to western gall rust (Endocronartium harknessii), st alactiform blister rust (Cronartium coleosporioides), needle cast (Lop hodermella concolor), and sequoia pitch moth (Synanthedon sequoiae) (L epidoptera: Sesiidae) were investigated in a 21-yr-old lodgepole pine (Pinus contorta spp. latifolia) provenance-family trial with 778 wind- pollinated families in interior British Columbia. Selection efficienci es in expected improvement in resistance were compared among mass, fam ily, sequential family-and-within-family, and combined family/individu al index selection. Efficiencies in multitrait selection for overall r esistance to the four pests based on different selection indices were also compared. Individual heritability for incidence of western gall r ust was 0.50, stalactiform blister rust 0.32, needle cast 0.30, and se quoia pitch moth 0.21. Family mean heritabilities ranged from 0.39 to 0.65, The genetic correlation between incidence of sequoia pitch moth and stalactiform blister rust was 0.89, and between pitch moth and wes tern gall rust 0.25. The genetic gain estimates from mass selection fo r resistance to the four pests varied from 14 to 31% at a 13% selectio n rate, On average, combined family/individual index selection was 5% more efficient than mass selection, and family and sequential family-a nd-within-family selection was about 38% and 16% less efficient than m ass selection, respectively, Substantial improvement can also be expec ted from provenance selection, Multitrait index selection for overall resistance excluding sequoia pitch moth data was nearly as efficient a s the full index. Indirect selection for resistance to sequoia pitch m oth based on resistance for stalactiform blister rust was more efficie nt than direct selection. Selection for resistance showed little adver se effect on growth.