Aerial application of fosamine ammonium or glyphosate at moderate rates was not adequate for controlling understory brush before final harvesting of mature Douglas-fir (Pseudotsuga menziesii) stands or for reducing vigor of post-harvest sprouting. Symptoms of herbicide injury were those associated with low application rates, suggesting that the canopy intercepted too much of the chemicals for adequate brush treatment. Site-preparation effects of logging were more pronounced than those of herbicide treatment in curbing future dominance by brush. Shrub species composition did not change as a result of spraying, logging, or both. Controlling understory brush with herbicides before harvest may require aerial application at higher rates or use of ground equipment where coniferous overstories are dense.
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