Reports of massive crop damage in several southern states caused by vaporized plumes of the herbicide dicamba that have spawned at least a half-dozen lawsuits and spurred state-level restrictions on the chemical's use have been of relatively little concern to regulators in Michigan. And that’s a shame.
Already used for decades on lawns, golf courses, corn crops, and other agriculture, uses of dicamba are anticipated to skyrocket in the near future as farmers are expected to scoop up new genetically-modified soybeans capable of metabolizing the herbicide. The new seeds allow growers to spray dicamba directly on and around soybean crops to kill weeds without damaging their genetically-modified plantings.
In Michigan, the new seeds could equate to dicamba being used on some two million additional acres of farmland every year. While that may be good news for soybean farmers who need to fight weeds that have grown resistant to other herbicides, it's a concern to those who aren't. It should also be a concern to all Michigan residents who care whether Michigan's lakes, rivers, streams, and groundwater – which serve as sources for our drinking water – are likely to become contaminated by the herbicide.
Dicamba poses a particular challenge because of the herbicide's tendency to volatilize, or evaporate, when it’s applied in warm temperatures, typically those above 85-degrees. For corn growers, who apply dicamba during cooler months, volatilization hasn't been a concern. But fluctuations in Michigan weather mean dicamba applications could vaporize with little notice. Once airborne, drift clouds are known to travel up to 10 miles, wreaking havoc on sensitive crops along the way.
Likewise, vapor drift means that dicamba that would have been broken down by plants and soils travel to unintended locations and enter local watersheds. Once in the water, dicamba can spread further.
To put it another way, it stands to reason that increasing the amount of herbicide applied increases the likelihood that it will appear in surface and groundwater. Or, as one university expert stated, "Increasing dicamba use by three to seven fold at a time when we are working to reduce exposure flies in the face of national policy."
Despite the risks associated with increased use of the herbicide, new use of dicamba on genetically-modified soybeans can be done without additional permits or regulatory oversight under the registration approval granted by the Environmental Protection Agency (EPA) to pesticide manufacturers. Federal law allows states to add additional regulatory restrictions, penalties or prohibitions beyond those imposed by the EPA and the United States Department of Agriculture.
Thus far, Michigan officials, who say the herbicide is a big deal in other areas but not in this state – yet – have adopted a wait-and-see attitude toward dicamba's use. Meanwhile, major crop injuries in other areas have led three states – Arkansas, Missouri and Tennessee – to take measures to temporarily ban the herbicide, impose additional restrictions and levy stiffer fines for its misuse.
Based on the likelihood that the use of dicamba will increase exponentially in Michigan, we urge state regulators to take a proactive approach to dicamba's new uses. Those actions should include, at minimum, stiffer fines for misuse or misapplication of dicamba. And, at best, additional restrictions on the use of dicamba applications that go beyond standard label instructions to protect sensitive crops and surface water points.
State agriculture officials report only two official complaints of crop damage from dicamba use since the new formulas were approved. We suspect there have been far more instances of crop damage, as many farmers are hesitant to raise tensions and possible conflicts by reporting their neighbors for unintentional events.
We also suspect Michigan's unseasonably cool temperatures this summer led to fewer cases of vapor drift than what we might witness in warmer years, which undoubtedly will occur.
Considering that warmer and wetter summers will spur additional weed growth, and in turn additional dicamba applications, it seems inevitable that dicamba drift will become a larger issue in Michigan, both with farmers and in the environment.
The fact that herbicide manufacturers have insisted their research shows new formulations of dicamba that won’t drift like those used illegally before the new product came to market is of little comfort. Subsequent testing has reportedly shown the new formulations do indeed drift. Whether those drifts are a result of incorrect application procedures remains to be seen, but should serve as yet another reason for Michigan to provide additional oversight on the herbicide's use.
State agriculture officials must consider both the wellbeing of Michigan's agricultural industry as well as the risks to the state's valuable water resources, and take proactive steps to protect them before the damage has been done.