Answer: This plant (Aegopodium) is legendary for its invasiveness. Unfortunately, I am not aware of any truly effective means to control it without using an herbicide. The root reserves of this plant are so tremendous that even an herbicide application may have to be repeated. Perhaps you could temporarily fence off the area to keep pets and children out, then use an herbicide containing glyphosate according to the label instructions. Another solution might be to start a new garden area at some distance from the goutweed. I'm sorry I can't be more encouraging.
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