Seletividade e eficácia das formula??es com os herbicidas atrazine/dimethenamid-p e atrazine/dimethenamid, no controle de plantas daninhas na cultura do milho

摘要

A trial was carried out to test the efficacy and selective of formulation and doses of atrazine/ dimethenamid-p andatrazine/dimethenamid, in pre-emergence on corn (cv. Primaiz BR 3101). The following treatments were tested in a sandy Red Yellow Latossol soil, in Uberaba, Brazil: atrazine 396 g/L/dimethenamid-p 204 g/L (1800, 2100, 2400 and 2700 g/ha) and atrazine 320 g/L/ dimethenamid 289 g/L (2100, 2400, 2700 and 3000 g/ha), s-metolachlor 960 g/L (2880 g/ha) and hand weeding and weeded. The mixture of atrazine/dimethenamid-p and atrazine/ dimethenamid, independently of the rates provided good control of the weeds Bidens pilosa, Portulaca oleracea, Commelina benghalensis and Digitaria horizontalis. No significant differences was observed in the productivities of the chemical treatments, but weeded treatment reduced 72% of the crop yield in relation to the hand weeding treatment. These was no difference among treatments concerning to the crops density, cobs numbers and first cob height and seed weight. The harvest index for mechanical harvesting in the chemical treatments was excellent. All the tested treatments were selective to corn.