Identificação, caracterização e controle alternativo de biótipos de Stellaria media resistentes a herbicidas inibidores da enzima acetolactato sintase

Abstract

The selection pressure imposed by the repeated use of acetolactate synthase (ALS) inhibiting herbicides has selected Stellaria media biotypes resistant to these products. The characterization of these biotypes is essential to establish management strategies that prevent the spread of resistance. Thus, studies were conducted with the objective of evaluating the level, the mechanism of resistance, and alternative herbicides for the control of S. media biotypes resistant to metsulfuron-methyl. The studies were conducted with resistant biotypes from Carazinho and a susceptible one from Passo Fundo. According to the results, the resistant biotypes require metsulfuron-methyl doses 8 times higher than the susceptible biotype to achieve a 50% reduction in dry mass. The resistant biotypes are controlled, in post-emergence, with herbicides that present alternative mechanisms of action, such as glyphosate, saflufenacil, glufosinate-ammonium, and diquat. The resistance mechanism is not associated with differential metabolism, or alterations in the ALS gene or enzyme.