This research comprised four experiments carried out under greenhouse conditions to evaluate the selectivity of herbicides, applied in pre-emergence conditions, on the following tropical grass forages: Brachiaria decumbens, Brachiaria brizantha cv. Marandu, Panicum maximum cv. Tanzânia and Mombaça. The herbicides and rates (g ha-1) applied for each experiment were alachlor (1.680 and 3,360), metolachlor (1,200 and 2,400), diuron (800 and 1,600), imazaquin (75 and 150), imazapyr (250 and 500), imazethapyr (50 and 100), clomazone (450 and 900), flumetsulam (70 and 140), ametryn (625 and 1,250), metribuzin (525 and 1,050), trifluralin (900 and 1,800), and a control plot, without herbicide aplication. The experimental design was completely randomized, with six replications. The spray volume was 180 L ha-1 by four flat fan spray (TEEJET 110.02). Plant intoxication was evaluated by visual grading . At the end of the study plant height and dry matter weight were evaluated. For P. maximum cv. Mombaça, only imazaquin (75 g ha-1), imazethapyr and flumetsulam at both rates tested were selective. For P. maximum cv. Tanzânia, none of the tested herbicides were selective. Regardeless of the rate, imazaquin, imazethapyr and ametryn (625 g ha-1) were selective to Brachiaria decumbens. For Brachiaria brizantha, the herbicides diuron (800 g ha-1), ametryn, imazaquin, imazethapyr and flumetsulam at both tested rates were selective.
Brachiaria decumbens; Brachiaria brizantha; Panicum maximum cv. Tanzânia; Panicum maximum cv. Mombaça
