How allelopathic is American Elm to garden vegetables, and to which plants?

I recently purchased some metal raised beds, and they recommended filling hugelkultur style – cardboard, then logs/branches, and finally compost and top soil. I diligently googled allelopathic trees to make sure my fill was safe … or so I thought.

While American Elm doesn’t come up in that search, it does when you google it directly. However unlike black walnut, it doesn’t give me any more info (chemical, toxicity, plants affected). My instinct is to empty the beds and start from scratch, but figured I’d reach out before I did.

Do you know how allelopathic American Elm is, what the main chemicals at play are (juglone or something else), and what vegetables are affected vs. undisturbed?

Thank you!

Posted by Kyle Schriver on May 22, 2022