By Leonardo Gottems, Reporter for AgroPages
Eduardo Cortés (Technical Advisor and Agronomist) highlighted the importance of developing a strategy to counter weeds in Argentina.
The information was presented during a field day event held by the The Argentine Association of Direct Sowing Producers (Aapresid) in Ibarlucea, Santa Fe.
”We must try to ‘confuse’ the weeds and focus on planning herbicide applications based on the situation and not on the type of herbicide. We must monitor, be on top of the situation and rotate active ingredients. It is proven that the pre-emergencies used today have a residuality that does not exceed 45 days,” Cortes said.
“We have reduced herbicide use by up to 40% by planning and knowing what to use, what it will be used for and what weeds it affect. Today, there are many populations with resistance to this family of herbicides and it is a very serious problem, since 99% of wheat herbicide treatments are based on this mode of action,” said Cortes, stressing that it is important to follow the logic of weeds to combat them.
He added that it is more interesting to copy what the weed does, stating, “Weeds that perpetuate themselves are born in litters or cuts, which can be two, three, four or five depending on the year and place where one works.”
He further explained that with a product that covers a timeframe of 45 to 50 days, you can not control a weed that lives for 90 or 120 days. Due to this reason, Cortes argued, “The idea is that we work through the various stages of application, which always achieves better results and at lower costs if a post-emergent must be applied later.”
The field trip, which was attended by producers seeking to deepen their knowledge of improving production, focused on weeds and pre-seed and post-emergent applications.
While touring the soybean plots, Cortés offered recommendations on the results observed in the field:
• Do not use Fomesafen as a pre-emergent if it is know that post-emergent applications will be done later.
• Sulfentrazone does not cause phytotoxicity, but S-Metalochlor does.
• S-Metalochlor effectively controls Eleusine and Echinochloa but not Chloris, which can be controlled by acetolactate synthase (ALS).
• There are no differences between Flumioxazin and Sulfentrazone in terms of controlling Amaranthus quitensis.
• All products need to be incorporated into a soil solution for efficient control, which requires water.
• Metribuzin as a pre-emergent that effectively controls both Conyza sp and Parietaria, with the latter weed becoming a recent problem.