In the WFDP: It is likely that western white pine is susceptible to suppression in this energy-limited system. The primary agents of mortality for western white pine in the WFDP are: mountain pine beetle (Dendroctonus ponderosae) and white pine blister rust (Cronartium ribicola).

Fire effects: Mature western white pine, with its moderately thick bark (3 cm), moderately flammable foliage, height, and evanescent [self-pruned away] lower limbs, is rated moderate in fire resistance. However, dense stands, lichen growth, and resinous bark can decrease western white pine's resistance to fire. Fire of any intensity will damage the cambium layer of young trees, usually resulting in death of the tree. In a mature western white pine stand, a cool fire will kill scattered trees, while only scarring others. However, the fire scars provide a vector for butt rots to enter the tree. Moderate to severe fire in a mature western white pine stand results in cambium damage and crowning, which usually results in the death of the tree. The large amount of humus in western white pine forests renders the trees susceptible to death from heating of the roots. After a stand-replacing fire, western white pine will seed in from adjacent areas. After a cool to moderate fire that leaves a mosaic of mineral soil and duff, western white pine will reoccupy the site from seed stored in the seed bank.

Pests and pathogens: The most serious damaging agent of western white pine is white pine blister rust (Cronartium ribicola). This rust was introduced into this country at the turn of the century from infected seedlings that had been imported from nurseries in France. White pine blister rust has a life cycle requiring alternate hosts for its completion: five-needled pines and currants (Ribes spp.). The rust produces spores on currants that infect white pines. These spores can be dispersed by wind up to 17 km. The spores germinate on the needles, and use the stomatal openings as a vector to the bole of the tree. This usually results in the death of the host tree. The most damaging root disease of western white pine is Armillaria spp., which causes fading foliage, growth reduction, dead and rotten roots, and black rhizomorphs, resulting in weakened or dead trees. Western white pine is susceptible to mountain pine beetle (Dendroctonus ponderosae) and emarginate ips (Ips emarginatus), and is the principal host for the ips beetle (Ips montanus).