[Phytotoxicity of di,sec.butylamides of halogenoalkoxybenzoic acids]

N,N-di,sec.butylamides of halogenated alkoxybenzoic acids were prepared and tested for phytotoxic activity. The corresponding acids and a series of N-alkyl- and N,N-dialkylamides of 2-methoxy-3,5-dichlorobenzoic acid were studied in parallel. The phytotoxicity of these substances was tested against seven representative weeds and some crop plants using both pre- and post-emergence test at doses of 6 kg/ha or lower. The amides studied proved more strongly phytotoxic on absorption through the root than through the foliage. Furthermore selective phytotoxic activity against two important infesting graminacae, Echinochloa crus-galli R.S. and Setaria glauca L. was observed. Some of these compounds showed low toxicity or were tolerated by crop plants. The results obtained with this series of amides of 2-methoxy-3,5-dichlorobenzoic acid confirm the importance of the sec.butyl group on N for the appearance of selective phytotoxicity.