Controle de plantas daninhas pela associação de herbicidas aplicados em pré-emergência e cobertura vegetal sobre o solo

Abstract

Currently, we can see the importance of soybean production in Brazil due to the size of the cultivated area and the large market that exists for this species. Because it has low competitive potential and high sensitivity, affecting its productivity and grain quality, weed control must be done with excellence. weed control must be carried out with excellence. It is common to combine pre-emergent herbicides, which will control the weeds at their most sensitive stage of development, with plant cover on the soil, which not only helps to control the weeds, but also brings various benefits to the crop. control, brings various benefits to the physical, chemical and biological quality and increases the soil's organic matter. The main weeds that interfere with the cultivation of this crop include Bidens pilosa, Euphorbia heterophylla and Amaranthus hybridus. They have cases of resistance to various herbicides. This study aimed to analyze the effectiveness of mulch combined with pre-emergence herbicides in managing these weeds. The weeds were analyzed separately in a completely randomized experiment with a 4 x 4 x 3 factorial design, with three replications. The following treatments were studied: diclosulan, flumioxazin and sulfentrazone, plus a control (no herbicide used) and three ground cover plants of the following species: Canavalia ensiformis, Pennisetum glaucum, Crotalaria juncea, in addition to a treatment with no three sheets of water immediately after the application of the herbicides (2.5, 5 and 10 mm). Control was assessed at 35 days after the treatments were applied (DAA) and the dry matter of the weeds was evaluated at the end. It can be concluded that A. hybridus was satisfactorily controlled (>80%) by the different mulches without the use of herbicides, but the association with the herbicides caused control close to 100%, especially with the 5 and 10 mm mulches. E. heterophylla was controlled satisfactorily (>80%) only when there was a combination of ground cover and herbicides, especially diclosulam and sulfentrazone with 2.5 and 5 mm of water after application. B. pilosa showed control greater than 80% with the presence of all ground covers, however, this control was greater when associated with the herbicides at 5 and 10 mm, resulting in control percentages of over 90% in most treatments. Cover crops should be considered when managing these weeds, especially if they are associated with herbicides moisture is needed after application to allow the products to percolate into the soil.