Control of Aspen Poplar , Balsam Poplar, and Prickly Rose by Picloram Alone and in Mixtures with 2,4-D

Abstract

Picloram alone and in combination with 2,4-D was evaluated for the control of aspen poplar (Populus tremuloides Michx.), balsam poplar (Populus balsamifera L.), and prickly rose (Rosa acicularis Lindl.) on rangeland in Saskatchewan which had alfalfa (Medicago sativa L.) as an important grazing component. The addition of picloram at 0.5 lb/acre to 2,4-D amine at 2 lb or less per acre did not improve the control of aspen poplar when compared to the presently recommended treatment in Saskatchewan of 2 lb/acre of 2,4-D ester. However, there was some evidence that the addition of 1 lb/acre of picloram to 2 lb/acre of 2,4-D amine may improve control. Picloram applied at 1 lb/acre alone or in combination with 2 lb/acre of 2,4-D amine provided effective control of balsam poplar. There was excellent control of prickly rose for 4 to 5 years following the application of 0.5 lb/acre of picloram with or without the addition of 2,4-D. The herbicide rates that were necessary for the control of any of the woody species, almost completely removed alfalfa from the rangeland. The significance of alfalfa on rangeland and the potential loss of grazing from using or not using herbicides is discussed.