Mistletoe infection of Douglas-fir and spruce seedlings increased as the mean dwarf mistletoe rating of the overstory, seedling density, and total age of seedlings increased. Percent of spruce seedlings infected increased more rapidly than for Douglas-fir as overstory dwarf mistletoe ratings increased. However, the intensity of infection as measured by the mean dwarf mistletoe rating of seedlings, increased at about the same rate for spruce and Douglas-fir. Percent infection of seedlings less than 20 years total age was higher for spruce than for Douglas-fir. Douglas-fir and spruce seedling mortality was from two to three times greater in heavily infested stands than in healthy stands.
Mathiasen, Robert L.
"Infection of young Douglas-firs and spruces by dwarf mistletoes in the Southwest,"
Great Basin Naturalist: Vol. 46
, Article 19.
Available at: http://scholarsarchive.byu.edu/gbn/vol46/iss3/19