An Alinement Chart for Estimating Number of Needles on Western White Pine Reproduction

Since its introduction into the West at Point Grey, British Columbia, in 1910 white pine blister rust has spread rapidly, and is now a major factor in the management of western white pine stands in northern Idaho. To study the relations between this species and ribes, the alternate host for white pine blister rust, some measure of the target afforded by the pines is imperative. The number of needles on a tree is the logical basis for indicating the target presented, since it is through the needles that pine infection takes place. The purpose of this paper is to make available a chart from which the number of needles presented by large numbers of white pine trees can be determined from measurements of crown length and crown width of the respective trees, correction factors being applied for abnormal trees.