Basal bark herbicide treatment of Lonicera maackii (Amur honeysuckle) is effective regardless of application timing, with limited nontarget effects on native plant diversity

Abstract

Abstract Managers tasked with controlling invasive species require effective methods that are quick and easy to use without inflicting extensive nontarget damage, while also being compatible with other scheduled management responsibilities. Lonicera maackii (Amur honeysuckle) is a non‐native shrub that has invaded eastern and midwestern North American deciduous forests, altering ecosystem function and reducing biodiversity. This study explores prescribed fire and seasonal basal applications of triclopyr ester as control methods and examines the extent of nontarget damage. We used paired‐split plots to implement basal bark treatments in different seasons within burned and unburned units, and we tracked individual L. maackii to determine mortality and hyperlocal impacts of management. Basal bark treatments killed 98.4% of L. maackii across seasonal timings. Nontarget plant cover declined similarly for all herbicide application seasons, but there were some signs of recovery within 4 years, and the early‐ and late spring treatments were less affected overall. Species richness showed biologically small but statistically different declines across treatment times. Prescribed fire did not impact L. maackii mortality or interact with herbicide efficacy. Basal bark applications of triclopyr are an effective means of L. maackii control regardless of application timing, which allows managers to implement it at their convenience to avoid interfering with other management tasks that have time constraints.