Residual herbicides in Roundup Ready soybean: A case study in multiple years and locations with Ipomoea triloba

Abstract

The evolution of glyphosate-resistant and -tolerant weeds has caused changes in weed management around the world. Residual herbicides are crucial tools for weed management, but the rate of adoption by soybean growers remains very low in Brazil. In this research, we used glyphosate tolerant Ipomoea triloba as a model weed species to evaluate the advantages of using residual herbicides on soybeans in multiple years and locations of transition and Cerrado regions of Brazil, rather than relying only on post-emergence control. Most residual herbicides provided enough residual activity to allow a longer application window in post-emergence. Treatments with residual herbicides increased overall weed control, preventing weed interference and increasing soybean yield. When two residual herbicides were used as opposed to only one, a better I. triloba control was achieved, reflecting in higher crop yield, especially in conditions of high weed infestation. The use of pre-emergence herbicides allows growers to have a longer application window for the post-emergence treatment, which is particularly important in Brazilian Cerrado large fields when logistic could be an issue.

Sourgrass Interference on Soybean Grown in Brazilian Cerrado

“…A maximum yield reduction was observed infestation by sourgrass reached 8 plants m -2 (1064 and 1344 kg ha -1 , 31 and 32% for cultivars Garra ® and ST797 IPRO ® , respectively). Such losses in soybean yield demonstrate the importance of using pre-emergence herbicides (LÓPEZ-OVEJERO et al, 2019) and cover crops such as Congo grass (Brachiaria ruziziensis) (MAROCHI et al, 2018), which have lower costs when compared to the negative effects of sourgrass interference.…”

Chemical control of multiple herbicide-resistant Amaranthus: A review

“…2022;40(Spec2):e0202200062 https://doi.org/10.51694/AdvWeedSci/2022;40:Amaranthus009 herbicides in the weed control program allows for resistance management by adding more options of effective modes of action in the toolbox. These herbicides also prevent initial weed interference with the crops, which often leads to yield losses (López-Ovejero et al, 2019). In addition, residual herbicides decrease the weed density and size, which facilitates weed management in POST.…”

The straw presence preceding soybean crop increases the persistence of residual herbicides

“…Between the 1980s and the 2000s, when non-transgenic soybean cultivars were used, there was a predominance of the pre and post-emergent herbicides like Acetohydroxyacid Synthase (AHAS) and Acetyl Coa Carboxylase (ACCase) inhibitors. The intensive use of these herbicides led to the evolution of weed resistance cases between the 1990s and the 2000s (Adegas et al, 2017;Ovejero et al, 2019). The soybean cultivars resistant to glyphosate (Roundup Ready) were launched in 2005, and later on, other technologies were introduced providing farmers with different types of herbicide resistant cultivars.…”