Farmers know that a methylated seed oil is just the right choice for a herbicide — but which one? Or do you need a spreader-sticker to make that herbicide or insecticide just right? Turns out the adjuvant choice is getting more complicated, and the Council of Producers of Agrotechnology, which represents many adjuvant makers, wants to help clear the confusion.
“We estimate this business is somewhere between $750 million and $1 billion per year,” says Joe Gednalski, manager, CPDA membership and value promotion. “This is a sizeable business in the United States — and an important part of making herbicides work.”
Gednalski recently retired from a long career as director of product development at WinField United and has conducted research on the impact of spray nozzles and droplet distribution. He knows how an adjuvant can help, or hinder, a product’s performance.
In 2001, CPDA created a certification program for adjuvants that requires a product to clear 17 benchmarks to become certified. All claims must meet ASTM definitions. ASTM was once known as the American Society for Testing and Materials, and it is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems and services.
CPDA, working with ASTM, brought standard terminology to the industry — which, along with the certification process, was designed to bring some certainty to the adjuvant purchase.
Gednalski says the industry is working to get away from the “snake oil” feeling that many farmers had in the old days. Adjuvants not only play a role, but many crop protection products also now require application with an adjuvant.
He points to older research that still holds value. It shows that a product applied without an adjuvant could see a 30% to 90% reduction in performance, but selecting the wrong adjuvant could cut performance by 5% to 50% and hold the possibility of increased crop injury. The right adjuvant can make a performance difference.
More crop protection companies are citing a preference for CPDA certification. In fact, 480 products now require use of a certified adjuvant. But the numbers get tricky after that. Only 180 adjuvants currently are certified by the group and carry the CPDA seal. Yet Gednalski notes that there are more than 2,000 adjuvants available to farmers, depending on the region.
“We haven’t increased the [certified] numbers,” Gednalski says. “We focused on the dicamba technology and getting adjuvants certified for the Enlist program, and CPDA took their eye off the ball — or most members did.”
He notes there is a renewed effort to bring up the level of awareness of certification and drive that message home to retailers. The fact that more manufacturers now require a certified adjuvant may bring some pressure to bear on those adjuvant producers that have not put their products through the process.
Bryan Young, a professor of botany and plant pathology at Purdue University, produces the biennial Compendium of Herbicide Adjuvants. This publication actually started in the 1980s, when George Kapusta, a weed scientist at Southern Illinois University, started gathering the information, Young explains. “I joined SIU in 1998 and took over the Compendium,” he says. “After 15 years at SIU, I’m continuing that at Purdue.”
The latest edition for 2020 should be ready by this fall. Young explains the new edition will feature more than 800 adjuvants, and that all companies can submit their products to be included. The guide also notes which adjuvants are CPDA-certified. But the challenge is adjuvant use itself. Some farmers don’t see value, even as more crop protection products require use of the additives.
Research judges adjuvant results
“Adjuvants perform based on the environment they’re applied in,” Young says. “If you have an optimal environment to apply herbicide, there may be little difference. But in those adverse weather conditions, the adjuvants do pay off.”
He notes that research continues on adjuvant use, just as it does with nitrogen use. “Adjuvants can be good insurance for your application,” he says.
Young explains that the CPDA certification is important because it denotes consistency in product, which should add up to consistency in performance. “And also, in many cases the company believes in their product, so they will go ahead and get it certified,” he notes.
Adjuvants do have a role in preventing herbicide resistance. Young explains that whenever you apply a herbicide, you want to optimize the product’s activity each and every time — which is what adjuvants are intended to do. “If you apply a herbicide but compromise the herbicide's activity, and get a level of surviving weeds that can reproduce over time, you’re selecting for resistance,” Young says. “That’s how glyphosate resistance happened. Some application methods were less than ideal.”
He adds that with fewer new modes of action coming to market, the concerns about resistance continue to rise. “We have to steward our current products the best way possible, including dicamba, 2,4-D and glufosinate — three key products in soybean production — and there are herbicide-resistant weeds right now."
Young explains that in this environment, adjuvants are just as — or more than — important today than in the past.
Gednalski adds that the rising use of multiple-mode-of-action tankmixes make selecting adjuvants even more important. “Finding the right adjuvant makes a difference in how the newest chemistry we have works,” he says.