Plantas daninhas importantes na cultura do algodão transgênico: manejo de Eleusine indica (L) Gärtner e Spermacoce latifolia Aublet.

Abstract

The weeds Eleusine indica and Spermacocea latifolia have become difficult to control in cotton and soybean areas due to herbicide resistance and tolerance, respectively. Due to this, this work aims to evaluate the efficiency of different herbicides in the management of these weeds. The experiments were carried out in a greenhouse and the seeds of the weeds S. latifolia and E. indica were sown separately, in order to obtain 5 plants per pot. The pots were kept in a greenhouse with automatic irrigation to maintain the necessary moisture for plant germination and growth. Two days after sowing, six treatments of herbicides were applied to the weeds in pre-emergence - diclosulam (35 g ai. ha-1), S-metalachor (600 g ai. ha-¹), Piroxasulfone (200 g ai. ha-¹ ) + flumioxazin (200 g i.a. ha-¹), diuron (2000 g i.a. ha-¹) and trifluralin (600 g i.a. ha-¹), plus the control. When the plants reached the phenological stage of 4 leaves, sequential application was performed with the desiccants diquat - 200 g i.a. ha-¹ or ammonium glufosinate - 400 g i.a. ha-¹ and without sequential with four repetitions each. Thus, for each experiment a completely randomized design was used in a 5x3 factorial scheme + control without herbicide for each species. It is concluded that for the control of E. indica the application of diclosulam with the sequential one with diquat and diclosulam with sequential one with glufosinate of ammonium obtained better results than the application of diuron alone, the other treatments did not differentiate sequential and isolated applications, being both satisfactory . For the chemical control of S. latifolia, the treatment with diuron alone obtained a lower control than diuron with glufosinate ammonium and diuron with diquat, the same was repeated for S-metalachor. For the other treatments, there was no difference between sequential and isolated application, both being satisfactory. The sequential application was important to reach the level of control in treatments with diclosulam in the control of E. indica and in the treatment with diuron in the control of S. latifolia.