Halauxifen-Methyl+Diclosulam: New Option to Control Conyza spp. Prior Soybean Sowing

Abstract

Control of Conyza spp. prior to soybean sowing has faced difficulties because of the resistance cases in Brazil, hence new herbicides as halauxifen-methyl + diclosulam are important to manage this specie. The objective of this research was to evaluate the effectiveness of the herbicide halauxifen-methyl + diclosulam applied at pre-planting of soybean. The experiments were set up in three locations in Paraná State, Brazil, in the 2015/2016 season. The herbicide halauxifen-methyl + diclosulam was associated with glyphosate and compared to other commercial herbicide to Conyza spp. control. The application occurred 15 days before soybean sowing, in plants of Conyza spp. with an average height of 20-35 cm in the three areas. None of the treatments promoted Conyza spp. control above 90%, when soybean was at the V1 stage; however, the findings showed that halauxifen-methyl + diclosulam promoted better control in comparison to the other treatments. The control reached >90% at V3 soybean development stage, in which treatments containing glyphosate + halauxifen-methyl + diclosulam were more effective than the other treatments. In addition, treatments with glyphosate + halauxifen-methyl + diclosulam decreased dry matter content of Conyza spp. between 87 and 93%, depending on the location, when compared to the control. The burndown treatment to Conyza spp. with glyphosate + halauxifen-methyl + diclosulam did not decrease soybean yield, and it was always higher than the untreated check.

Multiple resistance of Conyza sumatrensis to three mechanisms of action of herbicides

“…Research conducted before the discovery of fleabane resistance to paraquat demonstrated satisfactory results for the use of ammonium glufosinate (Silva et al, 2014;Oliveira Neto et al, 2011;Moreira, Melo, Carvalho, Nicolai, & Christoffoleti, 2010). Also, to saflufenacil, which is a Protox inhibitor, and other new herbicides, positioned isolated and associated, in unique and sequential applications (Albrecht et al, 2018;Krenchinski et al, 2019;Cesco et al, 2019).…”

“…has gradually increased in cultivated agricultural areas in Brazil, primarily in soybean crops, becoming one of the primary weeds that interfere with this crop (Albrecht et al, 2018). After the harvest of off-season corn, interval occurs before sowing soybeans, and in this period, between the planting of the crops, fleabane develops significantly (Krenchinski et al, 2019;Cesco et al, 2019). This fact is due to the high adaptability of this plant to the production systems and the evolution of biotypes resistant to herbicides, which cause increasing losses to crops (Lamego et al, 2013;Albrecht et al, 2017;Cesco et al, 2019).…”

Sumatran fleabane (Conyza sumatrensis [Retz.] E. Walker) control in soybean with combinations of burndown and preemergence herbicides applied in the off-season

“…Studies highlight the effectiveness of herbicides with preemergence action in controlling Conyza spp. in soybean, for example, flumioxazin (PITTMAN et al, 2019), diclosulam (KRENCHINSKI et al, 2019), diuron (SANTOS et al, 2015), sulfentrazone (ALBRECHT et al, 2021), imazethapyr (ALBRECHT et al, 2020c) among others.…”

Herbicide alternative for Conyza sumatrensis control in pre-planting in no-till soybeans

“…Thus, the use of herbicides with different mechanisms of action, the combination of herbicides, and the adoption of other tools, in addition to chemical control, are essential in preventing the selection of resistant weed biotypes, as well as in their management (Gage et al, 2019). Studies show the effectiveness of dicamba (Flessner, Pittman, 2019), halauxifen (Krenchinski et al, 2019), glufosinate (Tahmasebi et al, 2018;Zobiole et al, 2018), saflufenacil (Budd et al, 2017), diclosulam (Braz et al, 2017, Krenchinski et al, 2019, especially in combinations, in the control of Conyza spp. and that can be used as control options in the cases of resistance.…”