US EPA can strengthen its oversight of herbicide resistance with better management controls

The US EPA’s Office of Inspector General (OIG) found that the agency has taken few steps to address herbicide resistance. The EPA believes that a delay in herbicide resistance is in the “public good.” Delaying resistance minimizes the amount and type of herbicides applied to combat weeds, reduces human and environmental exposure, and increases grower productivity. However, the EPA has several management and oversight challenges related to the agency effectively addressing herbicide resistance. 

 

OIG found that the EPA uses the pesticide registration process to collect information on human health and environmental risks from pesticides used on herbicide-resistant weeds, but no information is collected regarding synergism. Synergy occurs when the effect of a mixture of chemicals is greater than the sum of the individual effects. 

 

In addition, labels for products such as glyphosate currently do not require information about the chemical pathway that describes how a herbicide causes harm to a plant (i.e., the “mechanism of action”). Not requiring this information on labels can result in the improper use of pesticides to combat herbicide-resistant weeds. The EPA’s pesticide registration and reporting processes also do not generate necessary herbicide resistance information for tracking, monitoring and identifying where resistance occurs. 

 

There is a lack of communication and collaboration between the EPA and its public and private stakeholders regarding herbicide resistance management. This limits the reach of actions proposed and taken by the EPA, the development of meaningful alternatives, and the agency’s ability to proactively respond to herbicide resistance in the field. The EPA also does not have measures to track its progress addressing and slowing the spread of herbicide resistance. With improved management and oversight controls, the EPA can be better prepared to assess and develop actions to address and prevent future herbicide resistance issues.