Seed Source Significantly Influences Growth Rates and Disease Resistance of Abies lasiocarpa Grown for Ornamental Nursery Stock and Christmas Trees, Poster Board #217

Trees from six corkbark fir (Abies lasiocarpa var. arizonica) and 10 subalpine fir (Abies lasiocarpa var. lasiocarpa) seed sources were grown at the University of Idaho (SREC) and three commercial nurseries in northern Idaho and northeastern Oregon. Post transplant mortality was highest during the first two years and was very high at two of the unirrigated nurseries. For the three plantings evaluated through 2006, survival averaged 76% and 80% for corkbark and subalpine fir, respectively. In SREC irrigated plots, survival averaged 96% and 99%, respectively. Spring frost damage occurred on 74% to 100% of trees during 2002–2006. In SREC plots, damage was minor and did not adversely affect tree appearance. Initial tree heights and growth rates varied significantly between seed sources. In general, corkbark fir grew faster than subalpine fir. After nine years, SREC mean corkbark tree heights ranged from 2.08 m [Santa Fe National Forest (N.F.)] to 2.89 m (Apache-Sitgreaves N.F.). Subalpine fir mean heights ranged from 1.31 m (San Isabel N.F.) to 2.27 m (Kaibab N.F.). Through 2006, tree heights at the nurseries were about 30% less for corkbark and 39% less for subalpine fir than for corresponding SREC trees. Corkbark fir proved moderately resistant to resistant to a Phoma-type fungal blight that affected current-season laterals. Three corkbark seed sources appeared suitable for ornamental landscape applications and Christmas tree production. Subalpine trees were more susceptible to Phoma blight and are questionable for general landscape applications. Two fungicide programs (Pageant or Pageant plus Bravo Weather Stik) provided control of the blight. Six subalpine fir and 25 corkbark fir at the SREC were selected for testing as possible cultivars for landscape use.