Like a car dealership slashing year-end prices to spur sales, Monsanto is offering cash rebates to farmers willing to stock up on dicamba, the problematic pesticide that triggered thousands of crop damage complaints across 3.6 million acres in 25 states.

The 50-percent-off fire sale on dicamba comes as several states are working to establish limits on use of the notoriously drift-prone pesticide.

Restrictions like those put in place this year by eight states pose a huge problem for Monsanto, which has aggressively marketed dicamba as the answer to the proliferation of superweeds fueled by overuse of the company's flagship pesticide glyphosate.

The pesticide maker assured farmers that if they planted Monsanto seeds genetically altered to withstand dicamba and glyphosate, they could spray their fields with dicamba throughout much of the growing season to kill the glyphosate-resistant superweeds that now infest millions of acres of U.S. cropland.

The pesticide giant is aggressively fighting back, not only to win the hearts of farmers by slashing dicamba prices but also by filing legal challenges to states that have imposed common-sense restrictions on its use.

The effectiveness of that campaign was on full view earlier this month when an Arkansas legislative committee backed away from approving a common-sense measure to ban use of dicamba from mid-April through October to prevent drift damage to crops in nearby fields that have not been genetically altered to withstand dicamba.

Instead of moving ahead with the very reasonable growing-season limits on dicamba use, Arkansas legislators were suddenly parroting Monsanto's talking points, suggesting the date restrictions were "arbitrary" because they weren't based on scientific studies.

In fact, Arkansas' proposal to restrict dicamba use, much like restrictions already in place in Minnesota, North Dakota and Missouri, was based on a very simple principle: What's sprayed on your field should stay on your field.

But that essential, bedrock principle of pesticide use has proved to be too high a hurdle for Monsanto's dicamba: One Missouri researcher went so far as calling the widespread drift damage from the pesticide as possibly creating the greatest amount of crop damage in a single season from a pesticide in U.S. history.

Yet, despite the on-the-ground evidence of dicamba-inflicted damage, Monsanto--the same company that refused to allow independent scientists to study its new dicamba products--is now asserting that dicamba restrictions are "arbitrary" because they're not based on scientific research.

The truth is that Monsanto wants no part of what independent scientists have discovered about dicamba because much of that research doesn't support the company's claims, which are based on in-house research that is not public.

The EPA's approval of new dicamba formulations for use on genetically altered cotton and soybeans was predicated on unpublished research by Monsanto that allegedly indicated the new versions of dicamba were much less prone to drift and volatilization than older dicamba products.

However, recent studies from independent researchers found little difference in volatility between older and newer formulations. Research out of the University of Arkansas, University of Tennessee and University of Missouri all show that newer dicamba formulations not only result in volatility, but do so at levels similar to older formulations, which are known to be highly volatile.

The fact is, all the best-available independent science suggests dicamba use is too risky once plants have emerged. So, sure, by all means, states like Arkansas should take Monsanto's advice and follow the science.

And that science would agree with Monsanto: States don't need to establish "arbitrary" dates for dicamba restrictions. They just need to ban use of the pesticide wherever crops have already emerged from the ground.

That's good science, whether Monsanto likes it or not.

Nathan Donley is a senior scientist at the Center for Biological Diversity.

Editorial on 12/24/2017