It’s been 30 years since the last new class of herbicides, HPPD inhibitors, launched, says Rex Liebl, herbicide global product development manager for BASF.  Many of today’s “new” chemistries are really old chemistries, such as 2,4-D and dicamba, now paired with tolerant traits.    

So where’s all the new chemistry? What’s up with the 30-year gap?

John Combest, communications manager with Monsanto, says it’s not for lack of trying. “We’re always looking to discover new chemistries and new classes of chemistries. That’s part of what we do,” he explains. “It’s really challenging, scientific work.”

Here are five reasons why discovering and launching new herbicide chemistry is so difficult:

1. It takes time. From discovering a compound to launching a new product, companies put in 10 to 14 years of research and testing, says John McGregor, early product development manager with Bayer. And in that time, companies like Bayer comb through 100,000 substances that may or may not fit the bill for a potential new herbicide. “There are many successes and many failures,” he notes.

See related story below: "Herbicides: From discovery to launch"

2. Herbicide discoveries wax and wane. During the 1980s and 1990s, new mode-of-action discoveries led to multiple new chemistries, McGregor explains. “There are only so many pathways or processes in the plant that you can exploit,” he notes. And those pathways are already the target of existing chemistries. Today, product development teams focus on unearthing any other possible pathway that could be used to control weeds. And that, McGregor notes, takes time.

3. Companies hit the brakes. When Roundup Ready launched in 1996, glyphosate-tolerant corn, soybeans and cotton flooded the marketplace, and glyphosate quickly devalued the herbicide market, Liebl notes. Crop protection companies cut back on herbicide research in the early 2000s. Research efforts ramped back up after “holes” in glyphosate programs became clear. Today, BASF is funding herbicide research at preboom levels, Liebl adds.

4. There are fewer players. More than 20 crop protection companies worked on new product development during the herbicide boom of the 1970s and 1980s, Liebl notes. Today, only a handful of companies remain. He adds that a year from now, there could be four companies if pending mergers and acquisitions go through.

 “Clearly, to some degree, it’s about numbers,” Liebl explains. “When you have fewer companies involved, there are less opportunities to find [new active ingredients].”

5. Regulations complicate the process. The timeline isn’t longer, but the process is more complicated, Liebl notes. Regulatory agencies like the Environmental Protection Agency require additional studies to address honeybees, neurotoxicity, immunotoxicity and how the new active ingredient may impact non-target species, Liebl explains. “We have to demonstrate the compound is beneficial and that it should be commercialized,” he says. “And we have to prove the compound is safe for humans and the environment.”

Even though the quest to discover a new pathway and a new active ingredient is time-consuming, complicated and expensive, crop protection companies say they are up for the challenge.

“There may be fewer targets in the plant than we originally envisioned, making it harder to find the next generation. But we’ll find them,” Liebl says. “It’s an exciting time to be involved in herbicide development.”

Herbicides: From discovery to launch

The product development process may vary by each crop protection company, but John McGregor, Bayer’s early development manager, says the process breaks down into four areas: chemistry, biology, toxicology and environment.

Chemistry: The discovery phase, as McGregor explains it, is looking for that one unique compound, and then meticulously determining how to process and formulate it.

“We find something, we think there’s something here, and it makes sense to keep testing it,” says Rex Liebl, herbicide global product development manager for BASF.

Biology: The product is put through efficacy and performance testing in growth chambers, greenhouses and eventually fields across the globe, McGregor explains.

Product development managers look at rates, soil types, varieties, hybrids and how the product reacts in certain weather conditions, Liebl adds.

Toxicology: The potential new product faces several long-term studies, McGregor explains, making this one of the longest steps in the process.

“Regulatory has a whole list of tests and methodology applied to them,” Liebl says.

Environment: Regulatory agencies require data showing how the new active ingredient may impact the environment. “They want to know how the compound will behave in the soil, water and plants,” McGregor notes.

Regulatory requirements change and expand all the time. For example, drift concerns with dicamba and 2,4-D-tolerant crops need to be addressed, Liebl explains.

“We have to show how this new herbicide should be used and stewarded to help combat resistance,” McGregor notes. “This is a critical step in ensuring the sustainable use of any new herbicide.”