water and nutrient transport for large parts of the tree. Most of the breeding efforts for five-needle pine resistance are currently focused in North America, on P. strobus, P. monticola and P. lambertiana. The means of resistance in rust-resistant five-needle pine varieties involve various mechanisms, such as abortion of infected leaves and slow development of canker symptoms. It is likely that varieties exhibiting the latter mechanism act against the pathogen's ability to modify cell walls and avoid plant recognition. In some species of North American pine, hypersensitive responses to C. ribicola have been observed, which suggests a gene-for-gene interaction that may indicate that C. ribicola is not so ecologically foreign to North American pines as previously assumed. References External links Don't Move Firewood - Gallery of Pests: White Pine Blister Rust forestpathology.org Dorena Genetic Resource Center, United States Forest Service The Sugar Pine Foundation The Whitebark Pine Ecosystem Foundation Species Profile - White Pine Blister Rust (Cronartium ribicola), National Invasive Species Information Center, United States National Agricultural Library. Lists general information and resources for White Pine Blister Rust. Pucciniales Fungal conifer pathogens and diseases Fungi described in 1872