Abstract

Aclonifen is a herbicide with a diphenylether nucleus which has been authorized for agronomic use in France and Europe in 1983 (Corn, 1 kg.ha-1 and sunflower, 2.7 kg.ha-1 in pre-emergence) and in Turkey since 1994 (sunflowers, 1.8 kg.ha-1 and lentils, chickpeas, 0.75 kg.ha-1 ). This a.i. shows several characteristics which differ from the other members of its chemical family, especially its two complementary modes of action and a very high conjugation potential in sunflower. These features explain its high selectivity for sunflower and also explain that, after pre-emergence treatment, the a.i. was readily transformed into polar derivatives which remain segregated inside the roots. Thus, the chemical derivatives issued from the use of this a.i. are absent from the sunflower leaves and, consequently, from the flowers and the seeds. The modes of action, uptake, transfer and conjugation of this a.i. in sunflower, as compared to the weeds associated to this culture; show that not only pre-emergence treatments are possible for this a.i. but also post-emergence application