Efficacy of weed control and selectivity in soybean in the application of preemergent herbicides and their carryover in sorghum and maize.

Further studies are necessary to evaluate not only the effectiveness of preemergent herbicides for weed control and selectivity in soybeans but also the potential carryover damage to crops planted in succession, such as sorghum and maize. This study aimed to assess the efficacy of preemergent herbicides in controlling Euphorbia heterophylla L. and Digitaria insularis L., as well as their selectivity in soybeans (Glycine max L.) and the residual effects on crops sown in succession, including maize (Zea mays L.) and sorghum (Sorghum bicolor (L.) Moench). Two field experiments were conducted with soybean, both in a randomized block design, consisting of the following treatments: sulfentrazone + diuron, flumioxazin + imazethapyr, diclosulam, sulfentrazone, s-metolachlor and flumioxazin, in addition to weeded controls and without weeding, with four replicates. Subsequently, the sowing of maize and sorghum was performed. Visual evaluations of weed control were performed at 14, 21, 28, 35 and 42 days after application of the treatments (DAA) and of phytotoxicity in soybean, sorghum and maize at 14, 21, 28, 35 and 42 days after planting emergence (DAE), and at the end, yield estimate. It was found that the sulfentrazone, sulfentrazone + diuron and imazethapyr + flumioxazin treatments were effective in controlling D. insularis and E. heterophylla up to 42 DAA. For sorghum and maize, no significant injury levels were observed for any treatment, with the exception of sulfentrazone alone, which provided significant reductions in productivity.