Weed control in sunflower crop with application of aclonifen isolated or in mixture

Abstract

The aim of this work was to evaluate the selectivity and the efficacy of ac1onifen, isolated or in mixture with other herbicides, in postemergence weed control in a sunflower crop. The experiment was conducted in 1998/99, at the Experimental Farm ofMaringá State University, Paraná State, using the hybrid Morgan 742. The experimental design was randomized block with nine treatrnents and four replications. The evaluated treatments were: control (with and without hoeing), aclonifen (780 and 900 g/ha), quizalofop-p-ethy (75 g/ha), aclonifen +quizalofop-p-ethy (900 +75 and 900 + 100 g/ha), aclonifen +fomesafen (900 +25 g/ha) and aclonifen +chlorimuron-ethyl (900 + 2.5 g/ha). The treatments were applied when the sunflower plants were in V6 to V8, using a carbon dioxide-pressurized backpack sprayer, with a spray volume of 200 Llha. The mixtures of aclonifen + quizalofop-p-ethyl and the quizalofop-p-ethyl alone were seletive for sunflower and efficient in Cenchrus echinatus control, not differing significantly for the control. Ac1onifen.alone or in mixture with fomesafen, chlorimuron-ethyl and quizalofop-pethyl were efficient in the control of Commelina benghalensis and Portulaca oleracea not showing differences between these treatments and the control. Aclonifen alone or in mixture with fomesafen and chlorimuron-ethyl did not cause visual injury to the sunflower crop. The presence of weeds, especially C. echinatus, hindered the harvest and decreased the sunflower yield up to 50.0%.