Abstract The herbicides glyphosate and pyrithiobac inhibit the enzyme 5‐enolpyruvylshikimate‐3‐phosphate synthase (EPSPS) in aromatic amino acid biosynthetic pathway acetolactate (ALS) branched‐chain pathway, respectively. Here we characterise protease activity profiles of a sensitive (S), glyphosate‐resistant (GR) multiple‐resistant (MR) population Amaranthus palmeri response to pyrithiobac. A...