Abstract
The use of pre-emergent herbicides is important for the current agricultural production systems that present weeds resistant to herbicides. Considering the complexity of using these products, the objective of this work was to evaluate their selectivity and residual weed control in soybean crops and their effect on the weeds Amaranthus hybridus, Bidens pilosa, Digitaria insularis, Eleusine indica, and Euphorbia heterophylla. The herbicide selectivity experiments were conducted under field conditions in the 2017/18 and 2019/20 crop seasons and the herbicide efficacy experiments were conducted under greenhouse conditions. The herbicides s-metolachlor and flumioxazin can be applied on day of the soybean sowing without causing significant grain yield losses. Diclosulam and sulfentrazone are safe for soybean crops when applied at least 14 days before sowing. The herbicides used proved to be good options for weed management systems for soybean crops; flumioxazin and sulfentrazone were the herbicides that promoted the best control for all evaluated weed species and ensured a residual effect of at least 30 days.
Highlights
The competition of soybean (Glycine max) plants with weeds for environmental resources is frequently reported as a direct cause of grain yield losses, especially when they are not adequately controlled, decreasing grain yield in up to 82% (Silva et al, 2008).The most used method for weed manage is the use of herbicides
Soybean plants with Intacta 2 Xtend® are tolerant to glyphosate and Dicamba herbicides. These new technologies should be adoption with caution to mitigate the evolution of weeds resistant to these herbicides and avoid management errors that have been made with the use glyphosate in the past
Control 1 = plots were kept free of weeds throughout the experiment by manual hoeing; Control 2 = plots were kept without weed control
Summary
The competition of soybean (Glycine max) plants with weeds for environmental resources (water, light, and nutrients) is frequently reported as a direct cause of grain yield losses, especially when they are not adequately controlled, decreasing grain yield in up to 82% (Silva et al, 2008).The most used method for weed manage is the use of herbicides. The estimated annual cost with herbicide-resistant weeds in soybean crops may reach US$ 2.7 billion when production losses due this competition are considered (Adegas et al, 2017). In this context, two new technologies will be available in the years for soybean, EnlistTM (Corteva, Wilmington, USA) and Intacta 2 Xtend® (Bayer, Leverkusen, Germany). Soybean plants with Intacta 2 Xtend® are tolerant to glyphosate and Dicamba herbicides These new technologies should be adoption with caution to mitigate the evolution of weeds resistant to these herbicides and avoid management errors that have been made with the use glyphosate in the past
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