Herbicide efficacy in weed control increased due to by sequential application of glufosinate

The efficacy of glufosinate + saflufenacil in weed control is well known, but it remains unclear whether the sequential application of glufosinate + saflufenacil can increase the control efficacy of herbicides and what would be the best herbicide or herbicide mixtures used in the first application before subsequent application of glufosinate + saflufenacil? The objective was to evaluate the effectiveness of herbicides, followed or not by the sequential application of glufosinate + saflufenacil, in the control of Conyza spp. (fleabane) and Commelina benghalensis (Benghal dayflower) in the off-season, prior to soybean sowing. The experiment was conducted in 2020 in Palotina, Parana (PR), using a randomized block design with four repetitions. The treatments were arranged in a factorial arrangement (19 x 2), using 19 herbicides, namely glyphosate, glufosinate, carfentrazone, saflufenacil, dicamba, and 2,4-D, alone or in mixtures, for the first application. Next, we examined the effect of subsequent application of glufosinate + saflufenacil. The results showed that subsequent glufosinate + saflufenacil application increased the effectiveness of all treatments in controlling Benghal dayflower, regardless of the herbicides used in the initial application. The combination of glufosinate + saflufenacil effectively controlled the fleabane when given as the first or sequential application. However, single application in the off season, prior to the sowing of soybeans, is not the most viable indication. Our findings highlight importance of mixing saflufenacil with carfentrazone in the control of Benghal dayflower, and with dicamba in the control of fleabane.