Effects of dwarf mistletoe on growth and mortality of Douglas-fir in the Southwest

Authors

Robert L. Mathiasen, Forest Pest Management, USDA Forest Service, Ogden, Utah
Frank G. Hawksworth, USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, Colorado
Carleton B. Edminster, USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, Colorado

Abstract

The effects of dwarf mistletoe (Arceuthobium douglasii) on growth and mortality of Douglas-fir (Pseudotsuga menziesii) were studied on 387 plots in mixed-conifer stands in three national forests in New Mexico and two in Arizona. Analyses of 8,570 trees showed that low infection ratings (dwarf mistletoe classes 1 or 2) had no significant effect on tree growth, but that losses increased markedly as infection severity increased. Average volume growth losses for trees over 10 inches in diameter were: dwarf mistletoe class 3, 10%; class 4, 25%; class 5, 45%; and class 6, 65%. Mortality of Douglas-fir in stands severely infested with dwarf mistletoe was three to four times that of healthy stands. These high losses confirm the need for silvicultural control of Douglas-fir dwarf mistletoe in the Southwest.

Recommended Citation

Mathiasen, Robert L.; Hawksworth, Frank G.; and Edminster, Carleton B. (1990) "Effects of dwarf mistletoe on growth and mortality of Douglas-fir in the Southwest," Great Basin Naturalist: Vol. 50: No. 2, Article 9.
Available at: https://scholarsarchive.byu.edu/gbn/vol50/iss2/9