Studies in several areas in Arizona and New Mexico show that dwarf mistletoe (Arceuthobium douglasii) is rare in young Douglas-firs growing under infected overstories. Less than 5% of the Douglas-firs under 26 years old and less than 6% of those under 1.4m tall were infected in 77 mistletoe-infested stands. Both percent infection and mean dwarf mistletoe rating of young Douglas-firs increased as tree age, height, and stand dwarf mistletoe ratings increased.
Mathiasen, Robert L.; Edminster, Carleton B.; and Hawksworth, Frank G.
"Infection of young Douglas-firs by dwarf mistletoe in the Southwest,"
Great Basin Naturalist: Vol. 50
, Article 9.
Available at: http://scholarsarchive.byu.edu/gbn/vol50/iss1/9