Rusts - White Pine Blister Rust TYPE HOSTS  DESCRIPTION White Pine Blister Rust - Cronartium ribicola John W. Schwandt, USDA Forest Service, www.ipmimages.org The fungus attacks all five needle pines. Rough elongated cankers develop on trunks. Orange spore masses burst through cankered bark in early spring. Pitch flows around the canker wound. Controls: High humidity and temperatures of 60-75° F for 20 or more hours cause rust infection. Prune out and destroy infected branches.
Missoula County Extension Office; Missoula, Montana 59808 - Updated for 2006