Evaluation of Blade Plowing and Dot-Grid Herbicide Techniques for Selective Control of Trees on Electric Transmission ROWs

Charles E. Rowell, Kenneth W. Farrish, and James M. Dyer

A research project was conducted to evaluate two alternative vegetation management techniques on electric transmission line ROWs. The objective of the research was to test techniques that showed promise at reducing tree numbers on the ROWs, while maintaining maximum biodiversity of non-tree vegetation. Blade plowing and a dot-grid herbicide technique, using hexazinone and picloram, were evaluated on four study sites in Mississippi, Louisiana and Arkansas. The sites were selected to represent a range of soil types: loamy, upland, Coastal Plain soils; loess soils; poorly drained, fine textured, alluvial soils; and gravelly upland soils. Blade plowing, conducted during early summer, was deemed moderately effective (54–71% reduction in tree numbers) on the loess soils and on the upland, loamy and gravelly soils, and ineffective (14% reduction in tree numbers) on the poorly drained, fine textured, alluvial soils. The dot-grid herbicide technique was effective on the loess soils (78% reduction in tree numbers), performed poorly (28–54% reduction) on the upland loamy and gravelly soils, and was ineffective on the poorly drained, fine textured, alluvial soil. Biodiversity of non-tree vegetation remained high under both treatments when compared to the control (mowed-only). The cost of the dot-grid herbicide technique was considerably higher than that of the blade plow technique. The results of the work indicate that the blade plow technique has potential on upland sites as a selective, non-chemical approach to tree control on electric transmission ROWs. Further evaluation of blade plowing without preceding mowing is needed.

Keywords: Vegetation management, rights-of-way, biodiversity, dot-grid herbicide application method, tree control, blade plow, woody root management, hexazinone, picloram