Herbicidas aplicados na pré emergência da soja e efeito carryover para o milho

Abstract

The use of pre-emergent herbicides in soybean crops is an important tool in controlling weeds in soybeans, as they are products that control young weeds, in addition to having a residual effect. However, there is currently a lack of information on the selectivity of new products for soybean cultivation and carryover on crops sown in succession to soybeans. The objective of this work was to evaluate the effect of different pre-emergent herbicides on soybean crops and the carryover to corn crops. Two experiments were installed under field conditions in the agricultural years 2022/2023 and 2023/2024 on grain producing farms. 16 treatments were used, nine of which were herbicides; Pyroxasulfone, Imazetapyr, Flumioxazine, S-metolachlor, Fomesafen, Diuron, Clomazone, Diclosulan and Sulfentrazone, in addition to five double associations; Flumioxazin + Imazetapyr, Flumioxazine + Pyroxasulfone, S-metolachlor + Fomesafen, Sulfentrazone + Diuron and Pyroxasulfone + Imazatapyr, and finally two controls, one without weeding and the other with manual weeding. In general, the herbicides applied to soybean crops showed good weed control, with most of the molecules showing efficacy above 80%. The presence of a greater volume of straw in the system generates suppression of weeds, thus increasing the efficiency of herbicides. Pre-emergent herbicides can cause symptoms of phytotoxicity in soybean crops, however, depending on the production environment, they do not cause reductions in crop yield. Symptoms of intoxication were observed in corn plants, due to the treatments, but they did not affect the agronomic performance of the crop.