Dating white pine trees
Since its introduction, it has spread to 38 states and caused substantial damage and mortality especially in commercially valuable species of white pine.The disease continues to spread into high elevation areas where the effects go beyond the loss of individual trees.
The decline of pine species will likely affect squirrel populations and the carnivore species that depend on them, including possibly Canada Lynx.
Currently, stands of dead and dying whitebark pine trees can be seen in several western parks (e.g., Crater Lake, Glacier, and North Cascades).
This devastation may begin to affect the tourist economies of adjacent communities.
The following schematic depicts a simplified version of the life cycle of white pine blister rust.
Generally, white pine blister rust spores germinate on the plant surface and grow into the pine through the stomatal openings in the needles or a through a wound. The infected branch will often swell; after a year or more, the rust forms spores that are contained in blister - like sacks that erupt through the bark of the twig or stem.
During the progression of the disease branch death and topkill can significantly reduce cone and seed production and tree vigor.