Allelopathy is a complex phenomenon which Pliny the Elder, a Roman natural science author, first wrote about in 77 A.D. In his writings he noted the toxic effects of black walnut on neighboring plants in the landscape.
More: https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/430/430-021/430-021_pdf.pdf
Photo Source: https://pages.wustl.edu/mnh/common-trees-missouri