12.4 Discovering New Herbicides

Ever wonder how herbicides are discovered and developed?  Historically, pharmaceutical and petroleum companies would just take random chemicals that they had in their research and development areas and put them onto plants to see what happened.  Surprisingly this approach actually worked for discovering many of the herbicides used today.  However, it could take 30,000 different chemistries to test before they would find one that would be a good herbicide and not harm the crop, so it was quite a long process.   Another drawback was they did not really know the biochemistry of how the herbicide was affecting plants, nor any of the other properties like how it was absorbed.  That was not a concern at the time, though, as the focus was merely on the end result of controlling weeds.

Today, there are other approaches that developers are able to utilize.  In one approach, scientists are using computer simulations based on large data analysis. They can look at some of the biochemical processes in plants, including DNA sequences and structures of plant enzymes to design an herbicide which can interfere with one of these aspects of a targeted weed without harming the crops.  Computer simulations can also help anticipate any unwanted toxicities from different potential chemistries.

Due to the complexities and large expenses of developing and testing new herbicides, along with the regulations needed to insure their long term safety, limiting unexpected negative consequences, it has been a long time since new chemistries have become commercially available.  Therefore, it is extremely important that farmers and agronomists be good stewards of the herbicides currently available.  Part of this includes field practices that limit the probability of herbicide resistant weed populations from developing.  In order to do that, it is important to understand herbicide classification systems so that you are truly rotating herbicide chemistries in your management plans, as well as applying the herbicides in the most effective manner.