The dicamba dilemma

New rules for dicamba use

Dicamba, a popular agricultural herbicide that targets broadleaf weeds, has been around for nearly 50 years. However, the last few years have been filled with controversy about the application of dicamba. It’s most commonly used on genetically engineered soybeans but can also be applied to (modified) corn and cotton.

And dicamba is growing in popularity. Bayer, formerly Monsanto, expects that 60 million acres of their dicamba-resistant soybeans and cotton will be planted in 2019, up from 50 million in 2018. And as the most popular manufacturer of this kind of herbicide, its dicamba-resistant tolerant soybeans now make up of half of all U.S soybeans as of 2018.

Dicamba use and misuse

According the National Pesticide Information Center (NPIC), dicamba works by causing plants to grow in abnormal and uncontrollable ways, causing weeds — and non-resistant crops — to die. Since dicamba acts as a growth regulator, symptoms typically don’t appear until around 10 days after contact, and only appear on younger leaves and new growth. Dicamba injuries are easy to spot, as leaves will begin to blister and “cup” inwards, while also shrinking in size.

With dicamba misuse complaints on the rise, the Environmental Protection Agency (EPA) and several state agriculture departments have added new application restrictions for the 2019 growing season. While it’s unclear what long-term impact this will have, the hope is that these new restrictions will help mend fences between anti- and pro-dicamba farmers.

What is "dicamba drift?"

While dicamba is a boon to many farmers, it has one major downside. In hot weather, dicamba forms a gas that can drift for miles, hence the phrase “dicamba drift.” Unmodified crops and endangered plant species are especially vulnerable to this drift, leading to tensions between neighbors as injuries occur in nearby farms.

In 2018, the Illinois Department of Agriculture alone received 546 total complaints about pesticide misuse, 330 of which were dicamba-related. In the same year, the University of Missouri estimates almost 1.1 million acres of non-resistant soybeans were damaged throughout the U.S.

And because of dicamba drift, insurance carriers are seeing an unprecedented spike in dicamba-based crop claims, according Grinnell Mutual’s Claims Manager Vicky Hartgers. “It’s a challenge for everyone.”

How are dicamba regulations changing?

In response, the EPA has issued several new regulations to help curb the reach and impact of drifting dicamba, specifically for three new formulas: BASF’s Engenia, Corteva’s FeXapan plus Vapor Grip Technology, and Bayer’s XtendiMax with Vapor Grip Technology.

Changes include extending the registration until 2020 for over-the-top use, and new restrictions such as:

  • Only certified applicators can apply dicamba over the top (supervised, non-certified applicators may no longer apply)
  • Stricter over-the-top application deadlines after planting and for daily use
  • Reduced number of applications
  • More comprehensive tank clean-out guidelines
  • Larger buffers near endangered species

Hartgers says that with the new EPA changes, Grinnell Mutual hopes that “applicators will be far more aware and educated on the usage of dicamba products going forward.” 

Not only is the EPA enforcing new rules, but states like Illinois, Arkansas, Indiana, Minnesota, South Dakota, and North Dakota are implementing new guidelines for temperature cutoffs, wind-speed limitations, and buffer zones.

Check your state’s guidelines to find out what applies to you, and when these new rules go into effect.

The next steps for dicamba

The costs of dicamba drift damage continue to rise, and it’s important to note that federal crop insurance only covers weather-related perils, like flooding or drought, not chemical-related issues. Liability insurance may cover yield loss, but the challenge is pinpointing the dicamba source when drift occurs.

While the hope is that stricter guidelines will help decrease the number and size of these drifts, some farmers say the regulations may make it harder to farm and will hinder their yields. Other farmers and experts, however, still fear that these regulations may not be enough.

Dr. Bob Hartzler, an Iowa State University professor of agronomy and extension weed specialist, posted in his blog that while he believes the EPA is in a difficult position, he believes stronger restrictions are needed.

“The spread of multiple resistant weeds has greatly complicated weed management, creating the demand for new tools. Dicamba requires a much higher level of management than any other herbicide to be used safely,” he said.

Farm claims managers Hartgers and Ryan O’Roake say there are some simple ways to make a bad situation better. Farmers and applicators need to be aware of weather and wind speeds and should be talking to their neighbors about what’s been planted and what chemicals are being used. And those who use dicamba need to read and follow the updated label guidelines closely.

“Open communication is the key to strong partnerships between farmers, neighbors, applicators, and insurance agents,” O’Roake said. “Timely reporting of damage allows for earlier field inspections and presents more opportunities for mindful evaluations.”


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