An exotic fungus spreading southward through Rocky Mountain forests is threatening Colorado’s oldest trees — the gnarled limber and bristlecone pines that can live longer than 2,000 years.
White pine blister rust fungus afflicts hundreds of those trees on national forest land and in the Great Sand Dunes and Rocky Mountain national parks.
There is no known cure for the fungus, which penetrates pine needles, then covers branches with clamshell-shaped cankers and orange pustules, eventually girdling tree trunks.
“It’s killing trees in Colorado. And it is still spreading,” said Anna Schoettle, a U.S. Forest Service scientist.