Herbicide Selectivity applied in post-emergence of Mulato II grass

The objective of this work was to evaluate the selectivity of herbicides applied in post-emergence of mulato II grass, in different stages of forage development, in areas with in-row and broadcast seeding. In order to understand the influence of the time of application of the herbicides on the selectivity of mulato II grass, two experiments were designed: the first with application of treatments ۱۵ days after emergence (DAE) and the second to ۴۵ DAE. The experiments were installed in two areas, one with broadcast seeding and the other with in-row seeding. For all experiments, ۵ herbicides were applied in two doses, in the double control system: [aminopyralide+fluroxipyr] ۱.۰ and ۱.۵ L ha-۱, [۲,۴D+picloran] ۱.۵ and ۳.۰ L ha-۱, [aminopyralide+۲,۴-D] ۱.۰ and ۲.۰ L ha-۱, [aminopyralide+metsulfuron] ۰.۰۷۵ and ۰.۱۵۰ kg ha-۱ and [aminocyclopyrachlor+metsulfuron] ۰.۰۷۵ and ۰.۱۵۰ kg ha-۱. For applications performed at ۱۵ DAE only [aminocyclopyrachlor+metsulfuron] was not selective in both tested sowing systems. For applications performed at ۴۵ DAE in-row seeding, the treatments [aminocyclopyrachlor+metsulfuron] in the two tested doses and [aminopyralide+metsulfuron] in the highest dose caused injuries to mulato II grass. For applications carried out at ۴۵ DAE in a field sown by broadcast seeding, only [aminocyclopyrachlor+metsulfuron] caused injury to the culture. At all times of application, the herbicides [aminopyralide+fluroxipyr], [۲,۴-D+picloram] and [aminopyralide+۲,۴-D] in the two doses tested, proved to be selective for the fields sown by broadcast and in-row. In the second productive cycle, there was no negative effect of treatments in the four experiments.

Keywords:

Application stage , Brachiaria , Broadcast seeding , Grazing simulation , In-row seeding