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Managing Invasive Species

White Pine Blister Rust

White Pine Blister RustWhite pines play an important role in maintaining watershed health and providing wildlife habitat. Cronartium ribicola was introduced nearly 100 years ago; since then we have learned much about its basic biology and hosts. Early control efforts focused mainly on eradication of its alternate host, Ribes species, which proved helpful in the NE, but was unsuccessful in the West. Scientists also worked to develop disease resistant sugar pine, western and eastern white pines. Planting these valuable timber trees today can restore biodiversity and pest resilience to forest stands. Silvicultural strategies have been developed to augment their restoration, which requires large openings and fire to control competing vegetation. Pruning and thinning to remove rust infections can extend the life of planted pines. Active management can restore sugar pine, western and eastern white pine ecosystems, with the capacity for self-renewal, recovery, and ecological resilience. Less is known about managing blister rust in the high-elevation species.

  • All nine species of native white pine are at risk to the non-native fungus, Cronartium ribicola.
  • Ninety percent of western white pine-dominated forests have been taken over by more pest-prone species, e.g., firs, cedar and hemlock.
  • Disease resistant seed and seedlings of sugar pine, western and eastern white pines are being produced in Forest Service seed orchards and nurseries.
  • The potential for resistance in ecologically-important high elevation species such as whitebark or bristlecone pine is largely unexplored.
  • Bristlecone, foxtail, limber and whitebark pine are sometimes the only tree species that can survive in arid and high-elevation environments, where they regulate snow accumulation, stabilize soil, and provide critical wildlife habitat.
  • Wildlife at risk includes Clark’s nutcrackers, pine squirrels, black bears, grizzly bears, and many small seed-eating birds and mammals.