Effectiveness of Three Vegetation Control Methods in Establishing Compatible Plant Species in Powerline Rights-of-Way in Northeastern Québec

Yves Garant, Jean Domingue, and François Gauthier

Hydro-Québec periodically controls vegetation in its powerline ROWs to maintain network security and reliability. The efficiency of three control methods in establishing compatible vegetation was tested in Northeastern Québec: (1) manual cut, (2) manual cut plus  land application of Tordon 101 and TCA, and (3) aerial application of Tordon 101 and Silwet L-77. The purpose of the study was to compare the abundance of incompatible vegetation between sites, six years after the initial treatment. The area covered by incompatible stems was ranked based on three classes of vegetation homogeneity, using photogrammetry. Sampling plots were randomly distributed in vegetation zones in which the density of incompatible stems were measured and vegetation cover of mosses, herbs and grasses, woody vegetation and trees were determined. The most efficient method in controlling incompatible woody stems was aerial spraying of Tordon 101. Only 2,900 stems/ha were measured in these spans. Stem density of incompatible species was intermediate (14,184 stems/ha) after a ground application of Tordon 101 and TCA. A high density of 73,000 stems/ha was observed in spans that were treated by mechanical cutting.

Keywords: Herbicide, maintenance, manual cut, powerline, right-of-way, stems, TCA, Tordon 101, utility, vegetation