AN EVALUATION OF THE EFFECTIVENESS OF DWARF MISTLETOE SUPPRESSION

Dwarf mistletoe is a serious problem on the Flathead Indian Reservation. Since the early 197 - 0's, a procedure called thinning-sanitation has been applied to lightly infested stands. Evaluation of this procedure indicated that • • average dwarf mistletoe infection levels now range from 7 to 50 percent in larch and Douglas-fir treated 10 years ago. A second thinning, designed to remove the remaining infections, would leave an additional 30 percent of residuals infected. It is concluded that the thinning-sanitation procedure has not been effective in controlling dwarf mistletoe, even in what appear to be lightly infested stands. addressed the unevenaged management objective. The intent was to attempt the use of unevenaged manage- ment in lightly infested stands - those with up to one-third of the stems infected. The procedure, called thinning-sanitation, involved the selective logging of all visibly infected merchantable trees (those above 9 inches d.b.h.) at the first stand entry. The follow-up precommercial thinning removed infected individuals up to 7 inches • d.b.h., and on up to merchantable size if more than 50 percent of a tree's branches were infected. The procedure was later adjusted to remove all infected trees up to 9 inches d.b.h. during the precommercial thinning (second