The recent development of crop varieties resistant to the herbicide dicamba has led to changes in the law regarding the chemical’s use.
Image Credit: Clemson University Public Service and Agriculture

CLEMSON — As farmers across the Palmetto State prepare for a new season, many will face new requirements to use a familiar weed killer: dicamba.

Marking its 50th anniversary this year as a registered herbicide, dicamba is a common chemical used to control a broad array of crop-choking weeds.

But the recent development of crop varieties with resistance the chemical — meant to make weed control more effective — has led to complaints that the herbicide has affected nearby crops that aren’t Dicamba-resistant.

“The U.S. Environmental Protection Agency registered new dicamba formulations in 2016 to spray on dicamba-tolerant soybeans and cotton,” said Katie Moore, who leads the Pesticide Safety Education Program for Clemson University’s Cooperative Extension Service and Regulatory Services unit.

“After about 3.6 million acres were damaged in the United States from dicamba volatility, drift and improper sprayer cleanout, the manufacturers voluntarily agreed to label changes with more restrictions,” Moore said.

The label changes, which carry the weight of law, have led to EPA-required training for many Dicamba-based products.

Moore has taken the information to Clemson Extension agronomy agents across the state. The county agents, in turn, are offering training to the farmers and pesticide applicators who use Dicamba.

Training is offered at 6 p.m. today (March 7) at the Antioch Recreation Center in Hartsville (at the S.C. Young Farmer & Agribusiness Association monthly meeting) and at 10 a.m. Wednesday at the Tri-County Electric Cooperative in St. Matthews.

The training includes one pesticide recertification credit.

“These products — FeXapan herbicide with VaporGrip Technolgy, XtendiMax with VaporGrip Technology and Engenia — are restricted-use pesticides,” Moore said. “That means those buying and using these products must be a certified pesticide applicator. Purchasers and users also have to have annual training on these products annually in order to purchase and use them.”

The label now also requires specific records to be kept regarding the use if these products.

Other label changes include limiting applications to when wind speed is between 3 and 10 miles per hour, instructions for cleaning tanks and regulations on surveying for susceptible crops and sensitive areas before applying the herbicide.

“The label changes affect use patterns, application requirements and buffers, temperature inversions, record-keeping, tank cleaning, and off-target movement,” Moore said. “The goal is to provide farmers with the coverage they need while reducing the impact on neighboring crops.”