A field experiment was carried-out during 1989/90 at the Eldorado do Sul Experimental Station of Federal University of "Rio Grande do Sul", Brazil, with the objective of evaluating potential injury to sunflower by imazaquin and imazethapyr applied at three different dosages in pre-emergence (PRE) or preplant incorporated (PPI). In a soybeansunflower rotation, imazaquin presents greater potential injury to sunflower than imazethapyr. Imazaquin and imaze thapyr activities were not dependent on application method. It occurred severe herbicide injury when sunflower was assessed early in the season. Plant height assessed late in the season indicated that sunflower recovered from imazethapyr injury, but not from imazaquin injury.
Helianthus annuus; residual herbicide; dissipation of herbicides; soil persistence; crop rotation; imidazolinones