Conquering a Prolific Invader–Optimal Herbicide Rates for Controlling Chinese Tallow Tree

One of the most difficult-to-control and widespread invasive plants in the southeastern U.S. is the Chinese tallow (Triadica sebifera) tree. Chinese tallow is challenging to control due to its prolific seed production, rapid growth, and ability to readily resprout after chemical and mechanical treatments. Chinese tallow often invades wetland and riparian areas and outcompetes native vegetation, altering plant community structure and composition, and leading to negative impacts on resident species. Additionally, peer-reviewed research on the effectiveness of newer herbicides for inducing mortality of Chinese tallow and related herbicide costs is limited. The goal of our research was to determine the optimal herbicide rates that maximize Chinese tallow mortality while minimizing potential control costs associated with inefficient herbicide applications. We randomly applied aminocyclopyrachlor, imazamox, and triclopyr herbicides to individual Chinese tallow trees at three study sites using a structured approach with 25%, 50%, and 100% of the maximum labeled rates. Treatment type included both basal bark and foliar applications as well as untreated control trees. Results indicated that all herbicide treatment levels resulted in significantly higher mortality compared to the control groups, with aminocyclopyrachlor and imazamox having the highest mortality in the foliar and basal applications, respectively. Our findings provide land managers with evidence to make informed decisions regarding the efficient use of herbicides to control Chinese tallow.