Aplicações isoladas ou associadas de diuron, oxyfluorfen e prometryne para o controle de Euphorbia heterophylla

Pre-emergence herbicide application at the beginning of the crop cycle is a consecrated practice among cotton farmers. Although herbicides, such as diuron, oxyfluorfen and prometryn, are options for this crop, not much is known about their effect on Euphorbia heterophylla. This work aimed to elaborate dose-response curves for diuron, oxyfluorfen and prometryn in relation to E. heterophylla control, as well as to provide biological efficiency data for tank mixtures of these herbicides. Thus, six experiments were simultaneously carried out under greenhouse conditions, with three consisting of increasing doses of each herbicide applied isolated and three of tank mixtures of two herbicides. The dose-response curve was adjusted for % of biomass reduction at 28 days after application; I80 and I95 (respectively dose for 80% and 95% of weed control and biomass reduction), were also determined. Diuron, oxyfluorfen and prometryn applied alone were effective within the range of the doses evaluated to control E. heterophylla. In general, tank mixtures containing oxyfluorfen were considered additive or antagonistic, while tank mixtures of diuron + prometryn were additive or synergistic. Out of the three possible combinations evaluated, oxyfluorfen + prometryn resulted in the smallest number of combinations promoting acceptable control of wild poinsettia.