Residual Douglas-fir left after harvesting are dwarf mistletoe-infected and pose a threat to regeneration. Felling of residuals, coupled with planned slash disposal and thinning, will effectively reduce dwarf mistletoe intensity and increase future volume yields. The benefit/cost ratio based on timber values only, for the current rotation, is 0.041/1 at 10 percent and 1.793/1 at 6 percent. Elimination of dwarf mistletoe infection for several rotations will increase the benefit/cost ratio. Value added to the economy cannot be used in benefit/cost analysis, but will be a substantial sum. Control is recommended.