Dicamba

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EPA Approves Extended Usage

By MARK H. STOWERS

In 1967, Dicamba was first used as a broad-spectrum herbicide. With uses for both agriculture crops and on non-agriculture land such as golf courses, it has been used for decades to control broadleaf weeds. The main action of the chemical is that it produces uncontrollable growth that leads to plant death. Delta soybean and cotton farmers have relied on it in their battle with Palmer Amaranth also known as pigweed. 

Those who work with Dicamba, including farmers and ag pilots, have to be trained and registered before using the chemical. The EPA recently approved new five-year registrations for two dicamba products and extended the registration of an additional dicamba product. All three registrations include new control measures to ensure these products can be used effectively while protecting the environment, including non-target plants, animals and other crops that are not dicamba-tolerant. 

Two “over-the-top” (OTT) Dicamba products—XtendiMax with VaporGrip Technology and Engenia Herbicide were approved. They also extended the registration for an additional OTT dicamba product, Tavium Plus VaporGrip Technology. 

Mississippi Department of Agriculture and Commerce Commissioner of Agriculture and Commerce Andy Gipson knows the benefits of this chemical for farmers.

“I appreciate the Trump Administration’s efforts to repeal burdensome regulations that have hampered agriculture and commerce in the past. I look forward to further strengthening the relationship of the Mississippi Department of Agriculture and Commerce and the U.S. Environmental Protection Agency, as we work together to promote sustainable farms that provide food and fiber for our communities in a clean environment for everyone to enjoy.”

Used correctly, dicamba works brilliantly. But, misused and crop damage is irreversible. 

“Historically, it was used as an early season burn down prior to planting when the temperatures are cooler,” says Dr Brian Pieralisi, MSU Extension Cotton specialist. “It is volatile and there are newer formulations to reduce the volatility. The goal is to apply it in season. Pretty recent it was used in season over the top of Dicamba tolerant crops like cotton. It’s also been used in soybeans.”

Pigweeds are the primary target, but it is a broadleaf herbicide.

“It’s a category four auxin herbicide,” says Pieralisi. “In incredibly low doses it was once thought it could be used as a plant growth regulator.”

He notes, “the problem is, there are two technologies that are mutually exclusive. There is 2-4-d tolerant and Dicamba tolerant, but they can’t tolerate each other. In the farming season, you can have Dicamba off-target injury on off-target crops and on buffers outside the field like Oak trees and tree lines. The goal is to apply on-target where nothing moves. But, often-times you can get drift and susceptible species are out there and that can be a problem.”

Ag pilot, Glenn Holloway Jr. explains more about the chemical. 

“Dicamba is one of the better products that we’ve had but you have to be very careful with it and be mindful of the susceptible crops around the application area. In Mississippi, we have a cutoff date,” says Holloway. “We can’t put out any hormone type product from April 1st to September 30th – pretty much the growing season.”

Ag pilots are required to attend a one-time training in order to use the product.

“They basically tell you what nozzles to use, what pressure to run, cautions on tank mixes and how to clean out your machine before you go to another crop,” says Holloway. “You also have to take that class in order to purchase Dicamba. So, farmers who intend to use the chemical must have the license, to do so.”

Holloway also explains, “a group sued the EPA because they hadn’t done due diligence in licensing Dicamba and successfully got the license suspended the second half of this year. If you didn’t have it already bought and in your shed, you didn’t get any.”

The crop duster was able to purchase what he needed before the suspension and understands the need and benefits of the chemical.

“It’s a great product and a product that is needed until they can come up with some new chemistry,” he says. “That’s always the hard part, coming up with new chemistry. But it’s a great tool and one that’s been a great asset.”