Diclofop–methyl and haloxyfop–methyl (0.001 to 10 μM) caused 9 to 61% inhibition of 14C–acetate incorporation into lipids in corn leaf segments within 1 h of herbicide treatment, while neither herbicide affected this process in bean leaf segments. The herbicides did not affect 14C-malonate incorporation into lipids in corn leaf segments. Diclofop-methyl and haloxyfop-methyl reduced 14C-acetate incorporation into polar lipids and triglycerides in corn while incorporation into sterols was increased. In vitro activity of acetyl-coenzyme A carboxylase (EC 6.4.1.2) was inhibited from 26 to 94% within 5 min of exposure to the herbicides (1 to 10 μM). Diclofop acid inhibited this enzyme activity more than did haloxyfop acid. Differences in field activity between diclofop-methyl and haloxyfop-methyl are not related to differential sensitivity of acetyl–coenzyme A carboxylase to the two herbicides.
