Seletividade do herbicida dicamba aplicado em diferentes épocas em soja com tecnologia Xtend®

Abstract

Currently, the herbicide glyphosate has demonstrated resistance and tolerance in various weed species infesting agricultural crops in Brazil. In response to this, a dicamba-resistant soybean technology, called Xtend®, was developed, with the recommendation to apply the product during the pre-planting desiccation period. This study aimed to evaluate the selectivity of different doses of dicamba herbicide applied at various times on Xtend® soybean. A field experiment was conducted in a randomized block design, arranged in a 4 x 5 factorial scheme with four repetitions. Factor A tested the application of dicamba at different soybean growth stages: on the day of sowing, at V3, V6, and R1 stages. Factor B included dicamba doses of 240, 480, 720, and 960 g ha^-1 of active ingredient, corresponding to zero, half, the recommended dose, one and a half times, and twice the recommended dose, respectively. Increased dicamba doses showed higher phytotoxicity in soybeans, especially when used at the V3 stage. Water use efficiency decreased with increasing dicamba doses applied on the sowing day. Applying 480 g ha^-1 of dicamba at the V6 and R1 stages resulted in lower soybean grain yield.