Summary.2,4‐D‐amine, 2,4‐D ethyl ester, 2.4‐DB‐potassium. MCPA‐sodium, diquat and a 1:1 mixture of 2,4,5‐T butyl ester and 2,4‐D ethyl ester were applied to the tropical pasture legumeCentrosema pubescensBenth. (centro) grown either alone or withPanicum maximum Jacq.(guinea grass). Even at 0.5 Ib/ac (total) the 2,4,5‐T/2,4‐D mixture caused severe damage to seedling and mature centro. 2,4‐D‐amine, 2,4‐D ethyl ester and 2,4‐DB‐potassium were less damaging and there were only slight differences in response to these. Diquat at 0.25 Ib/ac desiccated centro seedlings, but most plants survived and grew satisfactorily. There was some evidence that the growth of mature centro was depressed least when the herbicides were applied during vegetative quiescence.Application just after the start of flowering altered the flowering pattern but did not reduce seed yields significantly. 2,4‐D‐amine at 0.75 and 1–5 lb/ac and 2,4‐D ethyl ester at 1.5 Ib/ac decreased the percentage germination of abraded seed. Diquat 0.25 Ib/ac applied at the start of flowering caused significant increases in top growth and seed pod numbers, possibly the result of modific