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 United States 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 optimal herbicide and rate combinations that maximize Chinese tallow mortality while minimizing costs. We applied aminocyclopyrachlor, imazamox, and triclopyr herbicides to randomly selected individual Chinese tallow trees (n = 960) at three study sites on Aransas National Wildlife Refuge 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. Chinese tallow mortality was significantly greater for all herbicide treatment levels than control groups. The two herbicides with the greatest mortality estimates were aminocyclopyrachlor (50% of maximum rate, foliar application, 92% mortality) and imazamox (100% of maximum rate, basal application, 93% mortality). Our findings provide land managers with evidence to make informed decisions regarding the efficient use of herbicides to control Chinese tallow.