An aerial application of phenoxy herbicide on 109 ha of naturally reseeded forest near Holberg, BC was monitored. The objective of this study was to examine herbicide drift and the effectiveness of buffer zones in reducing pesticide contamination of watercourses. The herbicide, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxy-acetic acid (2,4,5-T) in their iso-cotyl ester formulations was applied as a dormant treatment using diesel oil as a carrier. Results indicate that adherence to a 90-m buffer zone can reduce amounts of aerial-applied herbicides near water bodies but was not adequate to completely eliminate stream contamination. Small quantities of herbicide residue were detected in the water up to 4 hours after the spray application. The data obtained are used to formulate buffer zone recommendations for aerially applied pesticides.
Reid, D.S., Mullett, R.G.; Morley, R.L.. 1977. Monitoring of an Aerial Herbicide Treatment at Holberg, British Columbia (Monitoring Study No. 2). Ministry of Recreation and Conservation. Fisheries Technical Circular. FTC33