This blog is the fifth in a five-part series titled “The Truth About Glyphosate,” sharing the facts about glyphosate and its use in the wheat industry.
Thanks for following along to our “Truth About Glyphosate” series. In this final part, we take a look back with a recap of everything we’ve learned about glyphosate.
Have more questions about on-farm practices? Reach out to the experts who know it best – ask a farmer.
What is glyphosate?
Glyphosate is the active ingredient in many “non-selective” herbicide formulations, used to control weeds. Non-selective herbicides control most plants, while selective herbicides are designed to control specific types of plants. Farmers apply non-selective herbicides to control weeds before crop planting. Most farmers choose glyphosate-based herbicides because they are a simple and cost-effective way of controlling many types of weeds. Glyphosate-based products are popular outside of agriculture, too. They are also commonly used to control weeds in gardens and around lawns.
How much wheat receives glyphosate?
Only about 30 percent of the wheat acres in the United States are applied with glyphosate. Farmers make most of these applications before the wheat crop emerges. The U.S. Environmental Protection Agency (EPA), which regulates all pesticides including herbicides like glyphosate, refer to this use as a “burndown” or chem-fallow” treatment that are considered “pre-emergence” applications. These treatments occur when no wheat plants have emerged in the field.
Pre-harvest glyphosate application
Applications made when wheat plants are present in the field occur near plant maturity, or “pre-harvest’. The use of pre-harvest applications has declined over time and is currently below 2 percent of total acres. Cessna et al. (1994) examined levels of glyphosate in harvested wheat treated with glyphosate at different rates and at different times near harvest as grain moisture levels declined. In all cases, glyphosate residue levels measured below residue thresholds set by the EPA, regardless of application rates or timing. These results are consistent with EU data collected on glyphosate residues in cereal crops.
Transition to no-till
The United States Department of Agriculture (USDA) monitors and collects data on farm management practices in the United States. This data allows the USDA to accurately evaluate the safety of the nation’s food supply, assess risks and benefits, make decisions about product registrations, quantify the benefits of conservation practices and market commodities internationally. USDA data shows the percentage of no-till wheat acres with an additional rotation crop has increased from less than 5 percent to more than 20 percent of total acres in the northern and central Great Plains since 1989 (Hansen et al., 2012). An increase in no-till acres has lead farmers increase the use of pre-emergence glyphosate in order to manage harmful weeds.