Application time affects synthetic auxins herbicides in tank-mixture with paraquat on hairy fleabane control

Diecson Ruy Orsolin Da Silva,Dionei Schmidt Muraro,Adalin Cezar Moraes De Aguiar,Claudir José Basso

doi:10.1590/0034-737x202168030005

Diecson Ruy Orsolin Da Silva, Dionei Schmidt Muraro + Show 2 more

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https://doi.org/10.1590/0034-737x202168030005

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Abstract

Conyza sp. was the first glyphosate-resistant weed in Brazil’s soybean crop. Synthetic auxin herbicides followed by paraquat has improved the hairy fleabane control, and time of day of herbicide application can affect the control efficacy. There are no studies reporting the effects of the application time of synthetic auxins in tank-mixture with paraquat, or in sequential application with paraquat at two growth stages of hairy fleabane, applied at different times of the day. The herbicides were sprayed during the morning and night. 2,4-D applied alone was more effective applied during the day, while dicamba efficiency was higher when applied at night in the rosette stage. The mixture of 2,4-D and paraquat was more efficient when applied during the night. Tall hairy fleabane were more effectively controlled by dicamba + paraquat as well as any synthetic auxin followed by paraquat. When herbicides were applied at night, efficiency was slightly higher.

Highlights

Conyza sp. was the first glyphosate-resistant weed in Brazil’s soybean crop and causes severe yield losses in soybean (Agostinetto et al, 2017)
The herbicide efficiency is strongly dependent on the growth stage, and in a previous study, horseweed control was poor when herbicides were sprayed at plant higher than 30 cm (Kruger et al, 2010)
When 2,4-D+paraquat was applied during the night, it was more efficient compared with morning application, in both evaluations

Summary

Introduction

Conyza sp. was the first glyphosate-resistant weed in Brazil’s soybean crop and causes severe yield losses in soybean (Agostinetto et al, 2017). Was the first glyphosate-resistant weed in Brazil’s soybean crop and causes severe yield losses in soybean (Agostinetto et al, 2017). The evolution of glyphosate-resistant weeds has become a global issue problem in agriculture and 2,4-D and dicamba-resistant crops provide an alternative for postemergence applications of synthetic auxins on soybean. The hairy fleabane (Conyza bonariensis) emergence can occur throughout the year, with peaks in autumn and spring, with various weed size at the time of herbicide application (Vidal et al, 2007). The herbicide efficiency is strongly dependent on the growth stage, and in a previous study, horseweed control was poor when herbicides were sprayed at plant higher than 30 cm (Kruger et al, 2010). The harvest of winter crops prior to sowing of soybean is associated with the cutting of plants, which reduces leaf area and stimulates sprouting thereby generating new stems.

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