Estratégias de controle e artropodofauna de buva(conyza bonariensis) associada em lavoura de soja e em pastagem de inverno

Abstract

This work aimed to evaluate control strategies of hairy fleabane (Conyza bonariensis) and also study the arthropods associated with this weed. For this, the work was divided into three chapters. The Chapter I aimed to evaluate the selectivity of herbicides with potential use to control hairy fleabane on forming species winter pastures, which are: oats, black oats, ryegrass and tetraploid ryegrass. Experiments were conducted under greenhouse conditions and evaluated the phytotoxicity of plants and production of shoot dry matter (SDM). The treatments were: 2,4-D amine (806 and 1612 g a.i. ha-1), metsulfuron-methyl (2.4 and 4.8 g a.i. ha-1); clorimuronethyl (20 and 40 g a.i. ha-1); imazetaphyr (350 and 700 g a.i. ha-1); diclosulam (16.8 and 33.6 g a.i. ha-1); saflufenacil (35 and 70 g a.i. ha-1) and flumioxazin (50 and 100 g a.i. ha-1), and the control. According to the results obtained, the selectivity of herbicides is species cultivated dependent and it is important to know the botanical composition of pasture before applying any herbicide. In Chapter II aimed to evaluate the combination effect of the herbicides glyphosate and saflufenacil at different doses on the control of hairy fleabane plants. The treatments consisted of doses that followed the logarithmic scale, and used the herbicides glyphosate and saflufenacil both applied alone and in mixture. Were evaluated the visual control and the SDM production of hairy fleabane plants. The results indicate that there is a synergistic relationship between the herbicide glyphosate and saflufenacil. Also, the association of saflufenacil and glyphosate is effective in controlling glyphosate-resistant hairy fleabane. The addition of the herbicide glyphosate with saflufenacil, besides improve control, prevents the occurrence of regrowth of hairy fleabane plants. In Chapter III, hairy fleabane plants were collected fortnightly in Boa Vista and Sao Vicente Incra South in order to evaluate the arthropods associated with this weed. The results show that hairy fleabane takes an important role as an alternative host of important pests of the soybean, such bugs and caterpillars, and too natural enemies.