SummaryAbsorption, translocation and metabolism of14C‐pyridate were compared in tolerant maize. moderately susceptiblePolygonum lapathifoliumand susceptibleChenopodium album.Foliar absorption was limited in all species, but comparatively higher penetration levels were observed in younger leaves of dicotyledonous species. The absorbed radioactivity was not very mobile and translocation appeared mainly sym‐plastic. Herbicide selectivity could not be explained on the basis of absorption and transport.ChenopodiumandP. lapathifoliumdegraded pyridate and formed unstable water‐soluble conjugates that easily released a phytotoxic metabolite. By contrast, more stable unidentified water‐soluble metabolites were found in maize. That metabolic difference could explain the selectivity of p