Ailanthus (Ailanthus altissima) is an exotic invasive tree species that is becoming an increasingly common threat to native forest communities in the eastern United States. The species spreads aggressively by both seed and sprouts and produces allelopathic chemicals that may enable its spread. We tested two chemical control methods on Ailanthus (cut stump application with an aqueous 50% formulation of triclopyr vs. basal bark application using a 20% ester formulation of triclopyr). Each application was applied to replicated groups of trees in the spring following budbreak or in the fall before leaf fall. The cut stump application resulted in 100% control of Ailanthus (no resprouting) in both spring and fall, while the basal bark application was >90% effective (complete crown mortality). Spring applications were slightly more effective than fall applications for basal bark treatments. While chemical control appears to be an effective method for killing Ailanthus trees, abundant germination from the soil seed bank surrounding controlled trees will require long-term control efforts.
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