White pine blishter rust in the Rocky Mountain Region and option for management
Government Document
Transfer Guideline: Recommendation
Western USA
White pine blister rust (WPBR) is an exotic, invasive fungal disease of white, stone, and foxtail pines (also referred to as white pines or five-needle pines) in the genus Pinus and subgenus Strobus (Price et al. 1998). The disease, which is native to Asia, was accidentally introduced separately into eastern and western North America at the beginning of the 20th century. In the west, blister rust was introduced on infected eastern white pine (Pinus strobus ) nursery stock shipped to Vancouver, B.C. from France in 1910. Since then, white pine blister rust has spread throughout the distributions of sugar pine (P. lambertiana ), western white pine (P. monitcola ) and eastern white pine and all but the southern extents of whitebark pine (P. albicaulis ) and limber pine (P. flexilis ) and the western extent of southwestern white pine (P. strobiformis ). WPBR has not been found in most of the Rocky Mountain bristlecone pine (P. aristata ) range and is yet to be found on Great Basin bristlecone pine (P. longaeva ). It was once thought that the remote dry habitats occupied by these species would not support rust establishment, however WPBR can now be found at many of these sites. Cronartium ribicola, the fungus that causes WPBR, requires an alternate host, currants and gooseberries in the genus Ribes and possibly species of Pedicularis and Castilleja (McDonald et al. 2006, Zambino et al. 2007) to complete its life cycle. WPBR infects Ribes seasonally causing minimal damage such as leaf spots and premature defoliation; the infections are shed each year with leaf abscission. The disease is perennial on infected pines causing cankers that usually lead to mortality. WPBR has caused widespread decline and mortality over millions of acres resulting in dramatic changes in successional pathways and ecosystem functions and the disease continues to spread and intensify wherever five-needle pines occur.
