Stories | July 13, 2017 | Read Time: 7 minutes
Dicamba-based Herbicide XtendiMax® with VaporGrip® Technology: Years in the Making
As a Monsanto scientist, I’ve had numerous discussions about the technology we develop, our methods for testing it and the ways in which we work to make sure it meets farmer needs. Over the past several years, many of those conversations have turned to the need for new technology to tackle increased weed resistance. As my team saw problematic weeds like Palmer amaranth in farmers’ fields, we knew, as did the industry, that it was time to develop new herbicides that could help farmers improve crop performance.
In 2008, my team at Monsanto began researching a new dicamba formulation that would offer a valuable option for treating weeds that had grown resistant to other herbicides. As we developed what would become XtendiMax®, we discovered a new technology that would help minimize volatility potential—VaporGrip® Technology.
When developing any new technology, we at Monsanto go beyond standard testing to develop significant research data that ensures all testing needs and regulatory requirements are not only met but exceeded. This is the same approach we took with this new product, conducting years of research and testing.
The Environmental Protection Agency (EPA) then spent several years extensively reviewing and analyzing data and research conducted on the product, and on Nov. 9, 2016, the EPA announced, following a rigorous review, a label for this new formulation—XtendiMax® Herbicide with VaporGrip® Technology. This new dicamba formulation had reached its first milestone on the path to providing growers and applicators with an in-crop herbicide option that could be used over-the-top of Roundup Ready 2 Xtend® soybeans and cotton with XtendFlex® Technology.
Since receiving that label, we’ve been asked questions about the research and evaluation that went into this new product. How was it tested? Who tested it? What did results show? Let’s dive into some of those answers.
On-Target Application, Off-Site Movement
Making on-target applications and managing the potential for off-site movement are crucial when using an herbicide. When beginning our research, we kept in mind the three types of off-target movement that can occur with any herbicide.
- Physical drift is the physical movement of relatively small spray particles during spray application. Physical drift can occur with any pesticide application, and application requirements are put in place to help farmers and applicators control on-target application and minimize drift potential.
- Sprayer contamination can occur when there is pesticide residue remaining in sprayer components. Spray equipment that is improperly rinsed following previous loads should not be used to treat a crop that is sensitive to herbicides.
- Volatility is the movement of an herbicide as a gas or vapor after spray application. It results from molecules of the chemical vaporizing from the surface of the plants or soil into the air.
Volatility requires control, and we discovered a mechanism to help manage it in our new VaporGrip Technology. This new technology helps prevent the formation of dicamba acid, allowing farmers to see a significant reduction in volatility potential as compared to earlier dicamba formulations. Using published ASTM Humidome methodology, we discovered that this technology provides a 90 percent reduction in volatility potential compared to Clarity®, an older dicamba formulation.
Like any new product, we tested this new formulation in a variety of ways. This helped us confirm consistent results, including verifying that what we saw in our trials translated to the field.
- The Humidome method involves measuring air concentrations of dicamba to look at the differences in formulations at concentrations 2x the field rate. We tested VaporGrip Technology by spraying soil in a tray with the spray solution and then covered that tray with a lid to create a dome. Air was pulled through the dome into a glass tube containing a foam plug for 24 hours to simulate the air you would see in the field. The foam plug trapped the dicamba vapor volatilizing off the soil. We then extracted dicamba from the foam plug and analyzed it to see how much dicamba was trapped. Unlike anything we’d seen before, we had to re-run the test multiple times because our initial results didn’t detect dicamba – something we discovered was a result of the VaporGrip component. From that initial observation, we developed the formulation XtendiMax with VaporGrip Technology. Based on additional testing, we found results to be consistent with field volatility studies.
- A second type of testing is known as the Hoop House method. Within our greenhouses, we placed 32 Genuity® Roundup Ready 2 Yield® soybean plants, which are sensitive to dicamba, on a metal stand. XtendiMax with VaporGrip Technology was sprayed onto glass Petri dishes at 2x the field rate, and those Petri dishes were placed in the middle of the plants so that all the plants had the same exposure to any dicamba that could potentially volatilize. The metal stand, including plants and Petri dishes, were then covered in plastic and sealed for 24 hours to trap the formulation with the plants. The plants were observed for any response to dicamba from the new formulation, rating them at days 7 and 14 after exposure. We found our results to be like the Humidome method – showing a significant reduction in volatility i.e. low response in the soybeans as compared to soybeans exposed to historically more volatile formulations.
- Large-scale field volatility studies allowed us to confirm that the results found in other tests translated to actual field conditions. On multiple occasions, we conducted volatility field studies in the southern United States that adhered to Good Laboratory Practices (GLP), meaning we had to follow stringent, international standards that, if violated, could lead to criminal or civil penalties. During these studies, we used anticipated label application requirements as they were proposed at that time, and we sprayed multiple fields with XtendiMax with VaporGrip Technology to test the volatility of the formulation. These field studies confirmed the findings from our other tests—when XtendiMax with VaporGrip is sprayed at the anticipated label requirements, volatility can be reduced relative to dicamba formulations currently on the market.
Together, the data collected in the research summarized above shows that XtendiMax with VaporGrip is a reduced volatility formulation. We looked at results in the lab and in the field, and we also looked at dicamba vapor concentrations and sensitive plant responses. In all cases, the results were the same—XtendiMax with VaporGrip is a reduced volatility dicamba formulation.
Any pesticide, including herbicides, intended for commercial availability must undergo extensive evaluations by regulatory agencies, including the EPA. They assess health and safety data of an herbicide, review data to ensure the product meets their stringent requirements and set standards for how an herbicide should be used.
Throughout the several years during which the EPA was rigorously reviewing data related to XtendiMax and its predecessors, several Monsanto and university representatives had numerous discussions with EPA scientists to answer questions, share additional data, review proposed application requirements and explain our research. We spoke with scientists and regulators at the EPA, all of whom were dedicated to making sure that any new formulation approved for use had gone through their extensive review process. Those conversations were all held with the same goal in mind—give farmers another, much-needed, weed control tool.