SELECTIVITY OF GLYPHOSATE-TOLERANT SOYBEAN AND EFFICIENCY OF Commelina benghalensis CONTROL USING ISOLATED AND MIXED HERBICIDES

摘要

The objective of this study was to evaluate phytotoxicity effects of herbicides applied during post-emergence, either alone or in mixture with other chemicals in transgenic glyphosate-tolerant soybean (cv. M-SOY 8008 RR) and in Commelina benghalensis. Two experiments were carried out from January to May 2006, in pots, under uncontrolled conditions, at Plant Protection Department of UNESP, Jaboticabal (SP), Brazil. The following herbicides were used: glyphosate (1,20 kg a.e. ha(-1)), chlorimuron-ethyl (0,02 kg ha(-1)), lactofen (0,018 kg ha(-1)), fomesafen (0,25kg ha(-1)), flumioxazin (0,025 kg ha(-1)), imazethapyr (0,10 kg ha(-1)), chlorimuron-ethyl (0,01 kg ha(-1)) plus lactofen (0,096 kg ha(-1)), chlorimuron-ethyl (0,01 kg ha(-1)) plus fomesafen(0,125 kg ha(-1)) and lactofen (0,096 kg ha(-1)) plus fomesafen (0,125 kg ha(-1)). It was also used the glyphosate (0,60 kg a.e. ha(-1)) in mixture with chlorimuron-ethyl (0,01 kg ha(-1)), lactofen (0,096 kg ha(-1)), fomesafen (0,125 kg ha(-1)), flumioxazin (0,0125 kg ha(-1)) and imazethapyr (0,05 kg ha(-1)) and a no treated control. Also the sequential application of glyphosate (0,96 plus 0,72 kg a.e. ha(-1)) was used in the experiment with C. benghalensis. The association of glyphosate and conventional soybean herbicides caused soybean injury. In some cases, such as in the glyphosate-lactofen and glyphosate-flumioxazin mixtures, the symptoms were severe, with necrosis and clorosis. Although there were phytotoxic symptoms in the plant, the herbicidedid not affect vegetative and reproductive soybean development. The mixture of glyphosate to other herbicides and its sequential application did not control C. benghalensis, when sprayed in the tested doses and in plants with 4 to 6 expanded leaves.