Hi Michael,

Thank you for reaching out to the UNH Extension Infoline.

Bittersweet is definitely a challenge to control! I will be including a few resources for you below in regards to methods of management. In the Penn State article, it does list that a foliar herbicide application can be an option for any new growth after other methods have been taken to control the initial growth. 

https://extension.unh.edu/blog/2018/04/invasive-spotlight-oriental-bittersweet
https://extension.unh.edu/sites/default/files/migrated_unmanaged_files/Resource000988_Rep1135.pdf

Controlling Bittersweet
More Info on Bittersweet
Video on Controlling Bittersweet

https://extension.unh.edu/resource/invasive-plants-specific-methods-control - General Control Methods for Various Invasives

Bittersweet will continue to regrow if the roots are not damaged. Stems need to be cut and painted with an herbicide that will eventually kill the root. Spraying foliar herbicides directly on large portions of bittersweet (without harming roots) will not stop the growth from occurring. In situations where the bittersweet is significant, you can also try to reach out to a licensed pesticide applicator via NH Landscape Association. You'd want to look for individuals that are licensed in Category B for Vegetative Management.

I hope that this information helps. Good luck!

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