A report from USDA explores a number of issues related to the decline of glyphosate’s effectiveness and choices for managing resistance to it.
What is the issue? Glyphosate has been the most widely used herbicide in the United States since 2001. It effectively controls many weed species, and generally costs less than the herbicides that it replaced. Because several major crop varieties have been genetically engineered to tolerate glyphosate, crop growers can spray entire fields planted to glyphosate-tolerant (GT) varieties, killing the weeds but not the crops. This practice makes it easier to manage weeds using less tillage, which can help reduce soil erosion and improve soil quality and water conservation. However, glyphosate’s effectiveness is declining as weed resistance mounts—14 glyphosate-resistant (GR) weed species currently affect U.S. crop-production areas. GR weeds can reduce crop yields and increase weed-control costs, and recent surveys suggest that the amount of affected cropland is increasing. This study addresses several issues raised by the spread of GR weeds and the effect on U.S. agriculture.
What Did the Study Find? Reliance on glyphosate, by many growers, as the sole herbicide to control weeds is the primary factor underlying the evolution of GR weeds. Using glyphosate in isolation can select for glyphosate resistance by controlling susceptible weeds while allowing more resistant weeds to survive, which can then propagate and spread. Using herbicides with different modes of action, which affect susceptible weeds differently, and rotating their use over time can result in fewer herbicide-resistant weeds.
Para leer el informe completo del USDA, clic aquí.
Para leer el informe completo de ADAMA/FAUBA, clic aquí.