In the last few months there have been two examples where we have seen brand new biotech crops that are tolerant to relatively old herbicides. It feels a little bit like time travel.  Dow AgroSciences is developing 2,4-D tolerance trait for corn.  That is an herbicide which was first released in 1946.  Monsanto is developing a dicamba tolerance trait. That herbicide was first commercialized in 1967. Both have recently moved to the USDA comment period stage for their regulatory status.

Ok, going back 46 or 67 years isn't as exciting as traveling through space and time in, say, Dr. Who's Tardis (above), but it is an interesting phenomenon for agriculture.

As a 57-year old, I'm gratified that technologies of my general vintage are still relevant for agriculture.  But what is the deal?  Why are we talking about such old products?  What does this tell us about biotechnology, chemistry, and science in general?  I'd say several things:

  • Plant biologists are practical realists who anticipated resistance issues
  • A more diverse weed control "Toolbox" is always a good thing
  • Some old chemistry is actually very good chemistry
  • Its hard to find good, new herbicides

Plant Biologists Are Practical Realists Who Anticipated Resistance Issues

In a bit of  "time travel" of my own, I recently found a clipping from the 10/24/1996 Wall Street Journal that a friend had snail-mailed to me as people did in those days.  It was a very comprehensive article about the first big year of biotech commercialization, and it included the following passage:

 "...some scientists worry that chronic use of these types of crops might hasten the evolution of even tougher insects and weeds."  

That was something already being discussed in the mainstream press in'96.  Weed scientists anticipated glyphosate resistance development in weeds well before that. This is because, as biologists, they understood that some weeds have become resistant to almost all control strategies over time.  That is just the biology of putting a selection pressure on a diverse genetic base.  The dicamba resistance trait story is a good example of this sort of awareness in action.

One of those scientists, Dr. Donald Weeks of the University of Nebraska, began looking for a solution long before there was really a problem in farmer's fields.  I first heard about his work seven years ago, and by that time he had already identified a gene from Pseudomonas maltophila which could allow rapid metabolism of dicamba, engineered it into soybeans, and demonstrated that it conferred tolerance in the field. This took many years of effort which was followed by years of additional work by Monsanto after they licensed the technology from the University. Monsanto has also collaborated with BASF, the German agricultural chemical company, to develop new formulation technology for the old herbicide to deal with its volatility issues.

There has been much written on the blogosphere implying that glyphosate tolerant, "super weeds" are some unexpected and terminally detrimental down-side of biotech crops.  Fortunately both the academic and business entities involved with agriculture understand the perennial struggle with weeds, and have been proactively innovating to respond.

A More Diverse Weed Control "Tool Box" Is Always A Good Thing

Last week I emailed several prominent weed scientists and herbicide resistance experts to ask what they think about things like the dicamba and 2,4-D resistance traits.  I promised that I wouldn't quote them individually specifically to see if they would want to express concerns that might be controversial.  They all said that these new herbicide resistance traits are potentially good options to add to a more sophisticated weed management system.  They acknowledged that there are some weeds already resistant to each herbicide and some limited cross-resistance between them, but their bottom line was that these could be valuable new tools for growers if used properly.  The grower community has a good appreciation of the need for new tools.  There are also plenty of warnings being sounded about the need to be careful not to mis-use the new options.  In these cases, the tool box is being expanded by allowing existing herbicides to have new uses.

Some Old Chemistry Is Actually Very Good Chemistry

There are scores of products from the pre-EPA era of dicamba and 2,4-D that have either been banned or voluntarily withdrawn from the market as we have made great advances in both the environmental and health risk assessment of chemicals.  These two products are from the short list of "survivors" of this process, which means that they have been repeatedly scrutinized and still found to be acceptable.  Both have low mammalian toxicity.  The fact that they are still useful herbicides also suggests that they have not, like some chemistries, selected for resistance too fast in too many species.  These are essentially old work-horse chemicals that have proven their value.  They are long-since off patent, but both have volatility issues that have since been addressed by new formulation technologies.  Even so, no company has a lock on these markets, so their upcoming use is not an example of a biotech trait that provides any biotech company with a monopoly on the sale of a related, chemical product.

Its Hard to Find Good, New Herbicides

It has been 22 years since I was directly involved in the discovery process for new, synthetic agricultural chemicals, but I know how much research investment it takes to find those leads.  Recently, I have been amazed at the number of new fungicide and insecticide classes that have been found which are amazingly "soft" from both an environmental and health perspective. I'm impressed with what the discovery companies have accomplished here.  There have been some new herbicides discovered over those years, and even of late, but not nearly as many as with insecticides and fungicides.  It just seems to be difficult to find new herbicides.  In any case, this is one of the reasons that old standards like dicamba and 2,4-D still need to play an important role in practical weed control.

Conclusion

So, it is a fascinating scenario that chemistry from the 1940s to 1960s might become an even more important part of weed control decades later.  The significant challenge of feeding a growing and economically advancing world population requires on-going research in many fields.  It also requires the all important role of the grower who ultimately integrates a wide range of tools to improve productivity and sustainability of the farming enterprise.

Tardis image from Duncan Hall (Cradlehall)