HOW to
Identify White Pine Blister Rust and Remove Cankers
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Protection Ornamental and Christmas Tree Plantings
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Technical References
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White pine blister rust (caused by the fungus Cronartium ribicola J. C. Fisch. ex Rabenh.) was introduced into the United States about 1900 and has since spread throughout the range of white pine. The disease intensity varies throughout the range but is normally most severe where late summers (July-September) are cool (below 67º F) and damp, conditions necessary for blister rust infection. Thus, the farther north, the more blister rust.

The fear of blister rust has greatly limited the amount of white pine planted in the Lake States even though there are many suitable areas in the southern parts of the region where white pine can be grown with no significant mortality from blister rust. Red pine has often been substituted for white pine in the Lake States, but red pine is now experiencing many new and serious disease and insect problems of its own. Thus, there is renewed interest in white pine with the hope of achieving a better balance of conifer species in the Lake States that will help minimize disease and insect losses. The development of blister-rust-resistant white pine, the possible increase in natural resistance to the disease, the planting of white pine in low blister rust hazard zones, and the pruning of blister rust cankers in certain high quality white pine stands can help achieve this balance.

Toward this end, helps for identifying white pine blister rust and suggestions for controlling it by canker pruning are presented here.

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Forest Service Shield.