Correct weed management

To the at the same time that Brazilian agriculture changed to face the challenges imposed by weeds, a reaction of the flora is observed both in terms of diversity and herbicide tolerance. In this dynamic process, the revitalization of existing solutions, such as the use of pre-emergent solutions. However, it is necessary to bear in mind mind that this is just one of the answers and not the only solution to the problem.

Us In the last 20 years, Brazilian agriculture has undergone profound changes in the management of weed plants. Among the numerous changes, it is worth highlighting the appearance of species resistant to the main herbicides and the creation and use of plants transgenic plants resistant to glyphosate and glufosinate ammonium.

To the At the same time, as a result of so much evolution, there was a reaction from the weeds both in diversity and in tolerance to the most common herbicides frequent. It is the dynamism of nature clearly demonstrating its strength of reaction to man's attempts at imposition.

At the We are currently experiencing a phase of new transformation. Like waves that come and go Weed control techniques resemble these movements. O The use of pre-emergent herbicides had its moment of glory in the past in various crops such as soybeans, corn, cotton, among others. Then the herbicides emerging selective powders such as those from the group of ALS and ACCase inhibitors had a period of prevalence, later replaced by glyphosate with the Roundup Ready and GlyTol transgenic plants (soybeans, corn and cotton).

As adverse result of the ease of weed management provided innovation resulted in intensive use of these technologies, often without criterion. This resulted in the selection of tolerant weeds and resistant to these herbicides, something perfectly normal when exercising this selection pressure. Thus, the next “wave” requires more difficult and costly measures to prevent weed damage.

As changes in weed flora occur so subtly, nor The farmer always notices these changes in his daily life. And when your crop is taken over by a new species there is a surprise, as if there was an explosion of these infestations. A scenario that makes you hostage to more drastic controls.

A solution is not always in the technologies that are coming, such as tolerance to Dicamba herbicide, herbicides based on 2,4D or from the group of HPPD herbicides, the which seems once again to be the most efficient and easiest way to deal with plants weeds. It is necessary to distinguish what are good agronomic practices from controls “easy” ones that can disguise the repetition of the same mistakes.

One One of the answers (and not the only one) may be in the revitalization of pre- emerging. Within the scientific world, this subject is the subject of several dialogues. among weed experts as a measure of safety, support and sustainability of new technologies. It is up to all professionals in the field agricultural sector turn their attention to pre-emergent herbicides now with a vision aimed at avoiding the failures of the past and adding more knowledge recent.

A coexistence between all weed control technologies and different cultures may not be harmonious when there is no adequate use of any of these techniques without proper knowledge. As an example is possible to list the risks of residues or “carry over” of pre-treated herbicides emerging for later culture, when this is sensitive.

It is approach is increasingly common in agriculture developed in countries like the United States of America. Research seeks to better understand the entire herbicide degradation mechanism, which is essential to ensure the necessary security for good agronomic practices.

O emergence of new information technologies, using sensors and images can help to identify all weed outbreaks more clearly and in the future, better calibrate the quantities and doses of herbicides applied.

For the revitalization of old pre-emergent herbicides or just to make use of new pre-emergent herbicides, research is being conducted with compounds capable of protecting culture or “safeners”. Given this, there is a great expansion of weed control models to guide the farmer regarding the best tools in this area. This makes it essential the ability of technical assistants to develop the most appropriate methods for each farmer.

O weed management system must expand its paradigms and to provide the most efficient and effective solution for the farmer, he must seek the best combination of weed control strategies. That includes, without a doubt, the use of all resources, including pre-emergent herbicides in the traditional way before sowing the crop of interest or after post-harvest control (at the discretion of a good harvesting professional) agricultural area).

Evaldo Kazushi Takizawa, Ceres Agronomic Consulting

Article published in issue 231 of Cultivar Grandes Culturas, August, 2018.