Control of hardwoods improves douglas-fir growth
Evergreen broadleaf trees, such as tanoak (lithocarpus densiflorus [Hook & Arn] Rehd.) and madrone (Arbutus menziesii Pers.), infest almost a million acres, or 25 percent, of potentially productive redwood/Douglas-fir timber acreage in northern California and southwestern Oregon. The cut-surface method of injecting herbicides into the vascular systems of such undesirable tree species is an effective means of control. Recent interest in this method of hardwood tree control in forests can be attributed to several factors. One is the relatively poor long-term control of resprouting species provided by herbicide applications from aircraft. Another is that the cut-surface method increases selectivity; the user can treat only the trees he wishes to control, such as those of one species or size, leaving desirable trees. Cut-surface applications also confine the herbicide to the treated tree.