Efficacy of herbicides applied on different weeds at different times in mechanically-harvested sugar cane area

Abstract

The objective of this work was to study the agronomic effectiveness of herbicides used in raw sugar cane areas to control Euphorbia heterophylla and Ipomoea grandifolia. The herbicides trifloxysulfuron-sodium + ametryn - (27,77 + 1,097 g a.i. ha-1) and (37 + 1,463 g a.i. ha-1), mesotrione - (120 and 192 g a.i. ha-1), mesotrione + ametryn -(120 + 1,500 g a.i. ha-1), mesotrione + (trifloxysulfuron-sodium + ametryn) - 120 + (27.77 + 1,097 g a.i. ha-1), (trifloxysulfuron- sodium + ametryn) + (diuron + hexazinone) - (27.77 + 1,097 g a.i. ha-1) + (702 + 198 g a.i. ha-1) and metribuzin - 1,920 g a.i. ha-1 were applied under the following conditions: weed pre-emergence on sugar cane straw;weed pre-emergence on the soil, followed by straw cover and weed post-emergence by spraying on the straw in between the sugar cane rows. Additionally, checks were evaluated with and without weed control. The experiment was installed in a commercial sugar cane plantation, on loamy textured soil in Araras, SP. Based on the results obtained, it was concluded that herbicide application on sugar cane straw during weed pre-emergence negatively affected the effectiveness of mesotrione (120 g a.i. ha-1) and trifloxysulfuron-sodium + ametryn (27.77 + 1,097 g a.i. ha-1) and the mixtures mesotrine + ametryn and mesotrione + (trifloxysulfuron-sodium + ametryn); (the herbicides applied on post-emergence sugar cane are selective for the culture; The herbicides metribuzin and (trifloxysulfuron-sodium + ametryn) + (diuron + hexazinone) were effective in the control of Euphorbia heterophylla and Ipomoea grandifolia, regardless of type of application.