Intensification of dwarf mistletoe on Southwestern Douglas-fir

Using Pseudotsuga menziesii infected with Arceuthobium douglasii 3 models for predicting mistletoe intensification are developed. Two models relate the mean rate of intensification since the tree became infected to initial and current tree conditions; the 3rd one describes the proportion of trees that increased by 0, 1, 2, or more classes of dwarf mistletoe infection (DMR) in the past 10 yr. The models suggest that the rate of intensification is most rapid (2 DMR classes per decade) for severely infected trees of small diameter and slowest (0.5 DMR classes per decade) for lightly infected trees of large diameter. Intensification within a tree increases with the abundance of mistletoe in nearby, larger trees and with stand basal area. -from Authors