Agronomic performance of wheat under post-emergence herbicide application1

Abstract

In addition to the herbicides already registered for the wheat crop, others may be selective, such as saflufenacil, atrazine, mesotrione and triclopyr. This study aimed to assess the selectivity of herbicides via crop yield analysis, alone and in mixtures, applied to wheat in post-emergence, at the end of tillering. Two experiments were conducted using a randomized blocks design. The first experiment (E1) involved 13 and the second one (E2) 7 treatments, consisting of the application of 2,4-D, diclofop, iodosulfuron, clodinafop, saflufenacil, pyroxsulam, atrazine, mesotrione and triclopyr, alone or in mixtures. Wheat injury symptoms, plant height, number of spikelets per plant, number of grains per spikelet, 1,000-grain weight and yield were assessed. The application of diclofop and iodosulfuron was selective to the wheat, maintaining yield even under the water stress conditions observed in E1. Under the same conditions, applying 2,4-D, clodinafop, saflufenacil, pyroxsulam, atrazine/mesotrione, triclopyr or saflufenacil + atrazine/mesotrione reduced the wheat yield, with different injury levels. Under greater water availability (E2), 2,4-D, clodinafop, saflufenacil, pyroxsulam and triclopyr were selective to the wheat, with no negative effect on yield. The application of atrazine/mesotrione showed a high injury potential for the crop and reduced the wheat yield.