A comparison of different chemical control application methods for managing Elaeagnus pungens in South Carolina

Several Elaeagnus species (autumn olive [ E. umbellata (Thunb.)], Russian olive [ E. angustifolia (L.)], and thorny olive [ E. pungens (Thunb.)]) are invasive in North America. Elaeagnus pungens is prevalent throughout much of the southeastern United States, commonly overtaking wooded and natural areas, bottomlands, and roadsides. While many management methods including several herbicide treatments have been evaluated, efficacy of these methods can vary based on the size and density of the target plants. Further, personal communication with land managers revealed a lack of information that incorporated application effort, duration and associated cost into treatment efficacy and usefulness. We evaluated three herbicide application methods using the free acid formulation of triclopyr in an E. pungens infested forest in South Carolina, United States to determine the effectiveness of each application method. We estimated pre-treatment E. pungens biomass and destructively harvested all live material post treatment to obtain actual biomass values. Foliar herbicide application was ineffective, but both cut stump and basal bark application nearly eliminated E. pungens in the treatment plots. The basal bark application took slightly more time to complete than cut stump treatments but was described as less physically demanding by applicators. Based on treatment efficacy and time required, the basal bark application method seems most prudent for controlling E. pungens in these areas. These results will help land managers more effectively use their resources for invasive woody plant control.