White Pine Blister Rust

A whitebark pine tree is infected with white pine blister rust, a deadly fungus. Orange-colored blisters are visible on the trunk.

This invasive fungal disease kills many whitebark pines in the Rocky and Columbia mountains. The fungus enters through the needles and then spreads, attacking tissue and disrupting the flow of nutrients. One sign of infection is orange "blisters" on the bark.