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Because of concern over widespread population declines, the distribution, stand conditions, and health of whitebark pine (Pinus albicaulis Englem.) were evaluated along the Pacific Crest National Scenic Trail on the Umpqua National Forest. Whitebark pine occurred on 76 percent of the survey transects. In general, whitebark pine was found in stands with lower overall densities and fewer late-seral species, particularly Shasta red fir (Abies magnifica var. shatensis A. Murr.) and mountain hemlock (Tsuga mertensiana [Bong.] Carr.). Whitebark pine stocking differed widely, from less than 1 up to 24 percent of the trees on transect plots. Most whitebark pines (87 percent) were less than 5 m tall. Of all whitebark pine encountered, 44 percent were alive and healthy, 46 percent were alive but infected by Cronartium ribicola (J.C. Fisch) (cause of white pine blister rust), and 10 percent were dead. Two-thirds of the mortality was due to white pine blister rust. Mountain pine beetle (Dendroctonus ponderosae Hopkins) alone accounted for 13 percent of the mortality, whereas evidence of mountain pine beetle was found with white pine blister rust on 18 percent of the dead whitebark pines. White pine blister rust affected trees in all but the largest size class; 70 percent of the whitebark pines greater than 1.5 m tall and less than 7.6 cm diameter at breast height (d.b.h.) were infected. Most (92 percent) of infected whitebark pines had bole cankers or cankers within 15 cm of the bole. No cones were observed on whitebark pines in any of the survey plots. Whitebark pine was common in centers of laminated root rot (caused by the fungus Phellinus weirii (Murrill.) R.L. Gilbertson) where substantial canopy openings were found. In these centers, whitebark pine contributed 73 percent of the large tree stocking. The results of this survey constitute a reference condition for whitebark pine that can be used to assess change in its status in this part of southwest Oregon. Measures to reduce the impacts of disease and bark beetles and to maintain whitebark pine populations are discussed.

The relationship between bark beetle infestation of ponderosa pine and severity of infection by Ceratocystis wageneri was investigated by closely monitoring 256 trees (136 apparently healthy, 60 moderately diseased, and 60 severely diseased at initiation of study) for beetle infestation from summer 1972 to fall 1975. Disease ratings were updated by periodic examination, and some trees changed disease category during the study. Ninety trees were infested by Dendroctonus brevicomis, D. ponderosae, or both, five by buprestids alone, and one tree died from effects of the pathogen alone. Sixty-two of the beetle-infested trees were severely diseased at time of infestation, 25 were moderately diseased, and only three were apparently healthy. Thus, the results showed that bark beetles were much more likely to infest infected than healthy trees. Among diseased trees, those with advanced infections were most likely to be infested. There was evidence that buprestids (especially Melanophila spp.) and possibly Ips spp. attacked diseased trees prior to Dendroctonus spp. infestation.