Abstract Glyphosate-Resistant Crops (GR crops) have caused considerable changes in weed management worldwide. In Brazil, GR cultivars of soybean and corn were officially introduced in the 2005/06 and 2011/12 crops, respectively. This technology has radically changed the weed management system, having an enormous impact on national agriculture. The objective of this review was to analyze the general aspects that led to the adoption of this technology in Brazil and present its future consequences and challenges. The adoption of GR soybean and corn was swift and comprehensive. Ten years after its introduction, GR soybean and corn are grown in most areas with these crops in Brazil. This success can be attributed to the reduction of costs, the broad spectrum of control provided by glyphosate, the solution for effective management resistance to ALS and ACCase inhibitors, the excellent managing of weeds that are difficult to control, the reduction of crop injury and carryover problems. However, the exclusive and consecutive use of glyphosate alone resulted in intense selection pressure for resistant weeds to this herbicide, which has become one of the most prominent challenges with these crops. Therefore, the future sustainability of GR soybean and corn will not be possible without the combination with other technologies, within integrated weed management.

Abstract Background This manuscript presents data of screening and dose-response curves of a goosegrass population from Primavera do Leste, MT, Brazil, which results in the first official report of multiple resistance of goosegrass to ACCase and EPSPs inhibiting herbicides in Brazil. Objective Evaluate the control of a goosegrass population from Primavera do Leste, MT, Brazil, suspected of resistance to the glyphosate, fenoxaprop-p-ethyl, and haloxyfop-methyl herbicides, using dose-response curves. Methods The study was carried out in two stages, the first in Brasília, DF, Brazil, and the second in Piracicaba, SP, Brazil. The first stage consisted in the initial evaluation and identification of resistance, which was confirmed in the second. In the first stage, the herbicides glyphosate, fenoxaprop-p-ethyl, and haloxyfop-methyl were applied to susceptible and resistant goosegrass populations (F1 and F2 generations) with plants with 2 and 3 tillers, using nine rates (0, 0.25, 0.5, 1, 2, 4, 8, 16, and 32 times the recommended rate). In the second stage, the herbicides were applied to susceptible and resistant populations with plants with 4 leaves, using 12 rates (0, 0.03125, 0.0625, 0.125, 0.25, 0.5, 1, 2, 4, 8, 16, and 32 times the recommended rate). Results The high sensitivity of susceptible plants combined with the high resistance level of resistant ones resulted in high resistance factors for fenoxaprop-p-ethyl and haloxyfop-methyl, with values greater than 27.8. The resistance factor for glyphosate ranged from 3.3 to 11, depending on growth stage at application time. Conclusions The goosegrass population from Primavera do Leste, MT, Brazil, presented resistance to EPSPs (glyphosate) and ACCase (haloxyfop-methyl and fenoxaprop-ethyl) inhibiting herbicides.

RESUMO Estudos sobre seletividade de herbicidas para a cultura da batata são poucos, especialmente em condições brasileiras. Por isso, objetivou-se estudar a ação fitotóxica de diferentes herbicidas para a cultura da batata, cv. Agata. Dois experimentos foram desenvolvidos em área de produção comercial, no delineamento experimental de blocos ao acaso, em esquema fatorial 7x2+1, em quatro repetições, de 14 de abril a 29 de setembro de 2016. Os tratamentos foram constituídos da aplicação de sete herbicidas em duas dosagens (ethoxysulfuron 45 e 90 g ha-1, halosulfuron 37,5 e 75 g ha-1, sulfentrazone 250 e 500 g ha-1, flumioxazin 17,5 e 35 g ha-1, clomazone 200 e 400 g ha-1, isoxaflutole 37,5 e 75 g ha-1 e oxadiazon 250 e 500 g ha-1), além de uma testemunha sem aplicação. O herbicida ethoxysulfuron foi pulverizado em pós-emergência nas plantas de batata, 4 e 7 dias após a realização da amontoa, respectivamente para primeiro e segundo experimento; e os demais em pré-emergência, após o plantio da batata. As duas dosagens de ethoxysulfuron ocasionaram injúrias visuais severas às plantas de batata, com reflexo na produção comercial de tubérculos. Entretanto, flumioxazin, halosulfuron, sulfentrazone, clomazone, isoxaflutole e oxadiazon foram promissores para uso na cultura em pré-emergência.

ABSTRACT Few studies on herbicide selectivity for potato crop can be found in literature, especially under Brazilian conditions. Therefore, the aim of this study was to analyze phytotoxic action of different herbicides for potato cv. Agata. Two experiments were developed under commercial field production conditions. A randomized complete block design, in factorial scheme 7x2+1, four replicates, was used, from April 14 to September 29, 2016. Treatments consisted of seven herbicides sprayed at two doses (ethoxysulfuron 45 and 90 g ha-1, halosulfuron 37.5 and 75 g ha-1, sulfentrazone 250 and 500 g ha-1, flumioxazin 17.5 and 35 g ha-1, clomazone 200 and 400 g ha-1, isoxaflutole 37.5 and 75 g ha-1 and oxadiazon 250 and 500 g ha-1) and also a control without application. Potato plants were sprayed with post-emergence herbicide ethoxysulfuron, four and seven days after hilling up, for the first and the second experiments, respectively; the other pre-emergence herbicides were sprayed after planting. The two doses of herbicide ethoxysulfuron caused severe visual injuries to potato plants, reflected in the commercial production of tubers. However, flumioxazin, halosulfuron, sulfentrazone, clomazone, isoxaflutole and oxadiazon were considered promising pre-emergence herbicides for potato crop.